2022/06/29 更新

写真a

カケヤマ マサキ
掛山 正心
所属
人間科学学術院 人間科学部
職名
教授

兼担

  • 附属機関・学校   グローバルエデュケーションセンター

  • 人間科学学術院   大学院人間科学研究科

  • 人間科学学術院   人間科学部通信課程

学歴

  • 1992年04月
    -
    1995年03月

    早稲田大学大学院   人間科学研究科博士後期課程   生命科学専攻  

学位

  • 早稲田大学   博士(人間科学)

所属学協会

  •  
     
     

    日本内分泌撹乱化学物質学会

  •  
     
     

    日本毒性学会

  •  
     
     

    日本衛生学会

  •  
     
     

    日本生物学的精神医学会

  •  
     
     

    日本神経精神薬理学会

  •  
     
     

    日本神経科学会

▼全件表示

 

研究キーワード

  • 行動神経科学

  • 予防医科学

  • 環境脳科学

論文

  • Neurochemical evidence for differential effects of acute and repeated oxytocin administration

    Seico Benner, Yuta Aoki, Takamitsu Watanabe, Nozomi Endo, Osamu Abe, Miho Kuroda, Hitoshi Kuwabara, Yuki Kawakubo, Hidemasa Takao, Akira Kunimatsu, Kiyoto Kasai, Haruhiko Bito, Masaki Kakeyama, Hidenori Yamasue

    Molecular Psychiatry   Sep 27   doi: 10.1038/s413 - (IF=11.640)  2018年  [査読有り]

     概要を見る

    © 2018, Springer Nature Limited. A discrepancy in oxytocin’s behavioral effects between acute and repeated administrations indicates distinct underlying neurobiological mechanisms. The current study employed a combination of human clinical trial and animal study to compare neurochemical changes induced by acute and repeated oxytocin administrations. Human study analyzed medial prefrontal metabolite levels by using 1H-magnetic resonance spectroscopy, a secondary outcome in our randomized, double-blind, placebo-controlled crossover trial of 6 weeks intranasal administrations of oxytocin (48 IU/day) and placebo within-subject design in 17 psychotropic-free high-functioning men with autism spectrum disorder. Medial prefrontal transcript expression levels were analyzed in adult male C57BL/6J mice after intraperitoneal injection of oxytocin or saline either once (200 ng/100 μL/mouse, n = 12) or for 14 consecutive days (200 ng/100 μL/mouse/day, n = 16). As the results, repeated administration of oxytocin significantly decreased the medial prefrontal N-acetylaspartate (NAA; p = 0.043) and glutamate–glutamine levels (Glx; p = 0.001), unlike the acute oxytocin. The decreases were inversely and specifically associated (r = 0.680, p = 0.004 for NAA; r = 0.491, p = 0.053 for Glx) with oxytocin-induced improvements of medial prefrontal functional MRI activity during a social judgment task not with changes during placebo administrations. In wild-type mice, we found that repeated oxytocin administration reduced medial frontal transcript expression of N-methyl-d-aspartate receptor type 2B (p = 0.018), unlike the acute oxytocin, which instead changed the transcript expression associated with oxytocin (p = 0.0004) and neural activity (p = 0.0002). The present findings suggest that the unique sensitivity of the glutamatergic system to repeated oxytocin administration may explain the differential behavioral effects of oxytocin between acute and repeated administration.

    DOI

  • 高次脳機能の健康を阻害する幼少期の環境要因と遺伝要因.

    掛山正心

    日本衛生学雑誌   73   110-114  2018年  [査読有り]  [招待有り]

    DOI

  • マウスにおける自閉スペクトラム発現の行動指標

    掛山正心, ベナー聖子, 藤原昌也

    日本生物学的精神医学会誌   29   103-108  2018年  [招待有り]

  • Excessive activation of AhR signaling disrupts neuronal migration in the hippocampal CA1 region in the developing mouse.

    Kimura E, Kubo KI, Endo T, Nakajima K, Kakeyama M, Tohyama C

    J Toxicol Sci.   4   25-30 - (IF=1.719)  2017年  [査読有り]

    DOI

  • Association of impaired neuronal migration with cognitive deficits in extremely preterm infants.

    Kubo KI, Deguchi K, Nagai T, Ito Y, Yoshida K, Endo T, Benner S, Shan W, Kitazawa A, Aramaki M, Ishii K, Shin M, Matsunaga Y, Hayashi K, Kakeyama M, Tohyama C, Tanaka KF, Tanaka K, Takashima S, Nakayama M, Itoh M, Hirata Y, Antalffy B, Armstrong DD, Yamada K, Inoue K, Nakajima K

    JCI Insight   2 ( 10 ) pii: 88609, (IF=13.251)  2017年  [査読有り]  [国際誌]

    DOI PubMed

  • Impaired dendritic growth and positioning of cortical pyramidal neurons by activation of aryl hydrocarbon receptor signaling in the developing mouse.

    Eiki Kimura, Ken-Ichiro Kubo, Toshihiro Endo, Wenting Ling, Kazunori Nakajima, Masaki Kakeyama, Chiharu Tohyama

    PloS one   12 ( 8 ) e0183497  2017年  [査読有り]  [国際誌]

     概要を見る

    The basic helix-loop-helix (bHLH) transcription factors exert multiple functions in mammalian cerebral cortex development. The aryl hydrocarbon receptor (AhR), a member of the bHLH-Per-Arnt-Sim subfamily, is a ligand-activated transcription factor reported to regulate nervous system development in both invertebrates and vertebrates, but the functions that AhR signaling pathway may have for mammalian cerebral cortex development remains elusive. Although the endogenous ligand involved in brain developmental process has not been identified, the environmental pollutant dioxin potently binds AhR and induces abnormalities in higher brain function of laboratory animals. Thus, we studied how activation of AhR signaling influences cortical development in mice. To this end, we produced mice expressing either constitutively active-AhR (CA-AhR), which has the capacity for ligand-independent activation of downstream genes, or AhR, which requires its ligands for activation. In brief, CA-AhR-expressing plasmid and AhR-expressing plasmid were each transfected into neural stems cells in the developing cerebrum by in utero electroporation on embryonic day 14.5. On postnatal day 14, mice transfected in utero with CA-AhR, but not those transfected with AhR, exhibited drastically reduced dendritic arborization of layer II/III pyramidal neurons and impaired neuronal positioning in the developing somatosensory cortex. The effects of CA-AhR were observed for dendrite development but not for the commissural fiber projection, suggesting a preferential influence on dendrites. The present results indicate that over-activation of AhR perturbs neuronal migration and morphological development in mammalian cortex, supporting previous observations of impaired dendritic structure, cortical dysgenesis, and behavioral abnormalities following perinatal dioxin exposure.

    DOI PubMed

  • In utero and lactational dioxin exposure induces Sema3b and Sema3g gene expression in the developing mouse brain

    Eiki Kimura, Toshihiro Endo, Wataru Yoshioka, Yunjie Ding, Waka Ujita, Masaki Kakeyama, Chiharu Tohyama

    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS   476 ( 2 ) 108 - 113  2016年07月  [査読有り]

     概要を見る

    In the developing mammalian brain, neural network formation is regulated by complex signaling cascades. In utero and lactational dioxin exposure is known to induce higher brain function abnormalities and dendritic growth disruption in rodents. However, it is unclear whether perinatal dioxin exposure affects the expression of genes involved in neural network formation. Therefore, we investigated changes in gene expression in the brain regions of developing mice born to dams administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dose: 0, 0.6, or 3.0 mu g/kg) on gestational day 12.5. Quantitative RT-PCR showed that TCDD exposure induced Ahrr expression in the cerebral cortex, hippocampus, and olfactory bulb of 3-day-old mice. Gene microarray analysis indicated that the mRNA expression levels of Sema3b and Sema3g, which encode proteins that are known to control axonal projections, were elevated in the olfactory bulb of TCDD-exposed mice, and the induction of these genes was observed during a 2 week postnatal period. Increased Sema3g expression was also observed in the brain but not in the kidney, liver, lung, and spleen of TCDD-exposed neonatal mice. These results indicate that the Sema3b and Sema3g genes are sensitive to brain-specific induction by dioxin exposure, which may disrupt neural network formation in the mammalian nervous system, thereby leading to abnormal higher brain function in adulthood. (C) 2016 Elsevier Inc. All rights reserved.

    DOI

  • Prenatal exposure to bisphenol A impacts neuronal morphology in the hippocampal CA1 region in developing and aged mice

    Eiki Kimura, Chieri Matsuyoshi, Wataru Miyazaki, Seico Benner, Mayuko Hosokawa, Kazuhito Yokoyama, Masaki Kakeyama, Chiharu Tohyama

    ARCHIVES OF TOXICOLOGY   90 ( 3 ) 691 - 700  2016年03月  [査読有り]

     概要を見る

    Bisphenol A (BPA), a widely used raw component of polycarbonate plastics and epoxy resins, has been reported to induce developmental neurotoxicity in offspring born to dams exposed to low doses of BPA; however, the toxicity mechanism remains elusive. To study the effects of in utero BPA exposure on neuronal morphology, we studied spine density and dendritic growth in the hippocampal CA1 of aged mice and developing mice prenatally exposed to low doses of BPA. Pregnant mice were orally administered BPA at a low dose of 0, 40, or 400 mu g/kg body weight/day on gestational days 8.5-17.5/18.5. Mouse progenies were euthanized at 3 weeks or 14 months, and their brains were analyzed for dendritic arborization of GFP-expressing neurons or spine densities of Golgi-stained neurons in the hippocampal CA1. Regardless of the dose, in utero BPA exposure reduced spine densities in the hippocampal CA1 of the 14-month-old mice. In the developing brain from the 3-week-old mice born to dams exposed to BPA at a dose of 400 mu g/kg body weight/day, overall length and branching number of basal dendrites but not apical dendrites were decreased. In utero low doses of BPA exposure disrupts hippocampal CA1 neuronal morphology during development, and this disruption is believed to persist in adulthood.

    DOI

  • Prenatal Exposure to Arsenic Impairs Behavioral Flexibility and Cortical Structure in Mice

    Kyaw H. Aung, Chaw Kyi-Tha-Thu, Kazuhiro Sano, Kazuaki Nakamura, Akito Tanoue, Keiko Nohara, Masaki Kakeyama, Chiharu Tohyama, Shinji Tsukahara, Fumihiko Maekawa

    FRONTIERS IN NEUROSCIENCE   10   :137, (IF=3.877, cited by 8)  2016年03月  [査読有り]

     概要を見る

    Exposure to arsenic from well water in developing countries is suspected to cause developmental neurotoxicity. Although, it has been demonstrated that exposure to sodium arsenite (NaAsO2) suppresses neurite outgrowth of cortical neurons in vitro, it is largely unknown how developmental exposure to NaAsO2 impairs higher brain function and affects cortical histology. Here, we investigated the effect of prenatal NaAsO2 exposure on the behavior of mice in adulthood, and evaluated histological changes in the prelimbic cortex (PrL), which is a part of the medial prefrontal cortex that is critically involved in cognition. Drinking water with or without NaAsO2 (85 ppm) was provided to pregnant C3H mice from gestational days 8 to 18, and offspring of both sexes were subjected to cognitive behavioral analyses at 60 weeks of age. The brains of female offspring were subsequently harvested and used for morphometrical analyses. We found that both male and female mice prenatally exposed to NaAsO2 displayed an impaired adaptation to repetitive reversal tasks. In morphometrical analyses of Nissl- or Golgi-stained tissue sections, we found that NaAsO2 exposure was associated with a significant increase in the number of pyramidal neurons in layers V and VI of the PrL, but not other layers of the PrL. More strikingly, prenatal NaAsO2 exposure was associated with a significant decrease in neurite length but not dendrite spine density in all layers of the PrL. Taken together, our results indicate that prenatal exposure to NaAsO2 leads to behavioral inflexibility in adulthood and cortical disarrangement in the PrL might contribute to this behavioral impairment.

    DOI

  • In Utero Bisphenol a exposure induces abnormal neuronal Migration in the cerebral cortex of Mice

    Wenting Ling, Toshihiro Endo, Ken-ichiro Kubo, Kazunori Nakajima, Masaki Kakeyama, Chiharu Tohyama

    FRONTIERS IN ENDOCRINOLOGY   7   :7  2016年02月  [査読有り]

     概要を見る

    Bisphenol A (BPA) has been known to have endocrine-disrupting activity to induce reproductive and behavioral abnormalities in offspring of laboratory animal species. However, morphological basis of this abnormality during brain development is largely unknown. Cerebral cortex plays a crucial role in higher brain function, and its precisely laminated structure is formed by neuronal migration. In the present study, transfecting a plasmid (pCAG-mCherry) by in utero electroporation (IUE), we visualized developing neurons and investigated the possible effects of in utero BPA exposure on neuronal migration. Pregnant mice were exposed to BPA by osmotic pump at estimated daily doses of 0, 40 (BPA-40), or 400 (BPA-400) mu g/kg from embryonic day 14.5 (E14.5) to E18.5. IUE was performed at E14.5 and neuronal migration was analyzed at E18.5. Compared with the control group, neuronal migration in the cortical plate was significantly decreased in the BPA-40 group; however, there was no significant difference in the BPA-400 group. Among several neuronal migration-related genes and cortical layer-specific genes, TrkB in the BPA-400 group was found significantly upregulated. In conclusion, in utero exposure to low BPA dose was found to disrupt neuronal migration in the cerebral cortex in a dose-specific manner.

    DOI

  • Chiba study of Mother and Children's Health (C-MACH): cohort study with omics analyses

    Kenichi Sakurai, Hidenobu Miyaso, Akifumi Eguchi, Yoshiharu Matsuno, Midori Yamamoto, Emiko Todaka, Hideoki Fukuoka, Akira Hata, Chisato Mori

    BMJ OPEN   6 ( 1 ) :e010531, (IF=2.413)  2016年  [査読有り]

     概要を見る

    Purpose: Recent epidemiological studies have shown that environmental factors during the fetal period to early childhood might affect the risk of non communicable diseases in adulthood. This is referred to as the developmental origins of health and disease (DOHaD) concept. The Chiba study of Mother and Children's Health (C-MACH) is a birth cohort study based on the DOHaD hypothesis and involves multiomics analysis. This study aims to explore the effects of genetic and environmental factors- particularly the fetal environment and postbirth living environment-on children's health, and to identify potential biomarkers for these effects.
    Participants: The C-MACH consists of three hospital based cohorts. The study participants are pregnant women at <13 weeks gestation. Women who underwent an examination in one of the three hospitals received an explanation of the study. The participants consented to completing questionnaire surveys and the collection and storage of biological and house/environmental samples. Participants were provided unique study numbers. All of the data and biological specimens will be stored in the Chiba University Center for Preventive Medical Sciences and Chiba University Center for Preventive Medical Sciences BioBank, respectively.
    Findings to date: Consent to participate was obtained from 433 women. Of these women, 376 women completed questionnaires in the early gestational period. The mean age was 32.5 (4.4) years. The mean body mass index (BMI) was 21.1 (3.0) kg/m(2). Before pregnancy, 72.3% of the women had a BMI of 18.5-24.9 kg/m(2). During early pregnancy, 5.0% of the participants smoked.
    Future plans: Primary outcomes are allergy, obesity, endocrine and metabolic disorders, and developmental disorders. Genome-level, metabolome-level, umbilical cord DNA methylation (epigenome), gut microbiota and environmental chemical exposure variables will be evaluated. We will analyse the relationships between the outcomes and analytical variables.

    DOI

  • Developmental origin of abnormal dendritic growth in the mouse brain induced by in utero disruption of aryl hydrocarbon receptor signaling

    Eiki Kimura, Ken-ichiro Kubo, Chieri Matsuyoshi, Seico Benner, Mayuko Hosokawa, Toshihiro Endo, Wenting Ling, Masanobu Kohda, Kazuhito Yokoyama, Kazunori Nakajima, Masaki Kakeyama, Chiharu Tohyama

    NEUROTOXICOLOGY AND TERATOLOGY   52   42 - 50  2015年11月  [査読有り]

     概要を見る

    Increased prevalence of mental disorders cannot be solely attributed to genetic factors and is considered at least partly attributable to chemical exposure. Among various environmental chemicals, in utero and lactational dioxin exposure has been extensively studied and is known to induce higher brain function abnormalities in both humans and laboratory animals. However, how the perinatal dioxin exposure affects neuromorphological alterations has remained largely unknown. Therefore, in this study, we initially studied whether and how the overexpression of aryl hydrocarbon receptor (AhR), a dioxin receptor, would affect the dendritic growth in the hippocampus of the developing brain. Transfecting a constitutively active AhR plasmid into the hippocampus via in utero electroporation on gestational day (GD) 14 induced abnormal dendritic branch growth. Further, we observed that 14-day-old mice born to dams administered with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dose: 0, 0.6, or 3.0 mu g/kg) on GD 125 exhibited disrupted dendritic branch growth in both the hippocampus and amygdala. Finally, we observed that 16-month-old mice born to dams exposed to perinatal TCDD as described above exhibited significantly reduced spine densities. These results indicated that abnormal micromorphology observed in the developing brain may persist until adulthood and may induce abnormal higher brain function later in life. (C) 2015 The Authors. Published by Elsevier Inc.

    DOI

  • Neuronal Heterotopias Affect the Activities of Distant Brain Areas and Lead to Behavioral Deficits

    Kazuhiro Ishii, Ken-ichiro Kubo, Toshihiro Endo, Keitaro Yoshida, Seico Benner, Yukiko Ito, Hidenori Aizawa, Michihiko Aramaki, Akihiro Yamanaka, Kohichi Tanaka, Norio Takata, Kenji F. Tanaka, Masaru Mimura, Chiharu Tohyama, Masaki Kakeyama, Kazunori Nakajima

    JOURNAL OF NEUROSCIENCE   35 ( 36 ) 12432 - 12445  2015年09月  [査読有り]

     概要を見る

    Neuronal heterotopia refers to brain malformations resulting from deficits of neuronal migration. Individuals with heterotopias show a high incidence of neurological deficits, such as epilepsy. More recently, it has come to be recognized that focal heterotopias may also show a range of psychiatric problems, including cognitive and behavioral impairments. However, because focal heterotopias are not always located in the brain areas responsible for the symptoms, the causal relationship between the symptoms and heterotopias remains elusive. In this study, we showed that mice with focal heterotopias in the somatosensory cortex generated by in utero electroporation exhibited spatial working memory deficit and low competitive dominance behavior, which have been shown to be closely associated with the activity of the medial prefrontal cortex (mPFC) in rodents. Analysis of the mPFC activity revealed that the immediate-early gene expression was decreased and the local field potentials of the mPFC were altered in the mice with heterotopias compared with the control mice. Moreover, activation of these ectopic and overlying sister neurons using the DREADD (designer receptor exclusively activated by designer drug) system improved the working memory deficits. These findings suggest that cortical regions containing focal heterotopias can affect distant brain regions and give rise to behavioral abnormalities.

    DOI

  • Application of NeuroTrace staining in the fresh frozen brain samples to laser microdissection combined with quantitative RT-PCR analysis Neuroscience

    Seico Benner, Masaki Kakeyama, Toshihiro Endo, Wataru Yoshioka, Chiharu Tohyama

    BMC Research Notes   8 ( 1 ) :252  2015年06月  [査読有り]

     概要を見る

    Background: The heterogeneity of the brain requires appropriate molecular biological approaches to account for its morphological complexity. Laser-assisted microdissection followed by transcript profiling by quantitative determination has been reported to be an optimal methodology. Nevertheless, not all brain regions can be identified easily without staining, restricting the accuracy and efficiency in sampling. The aim of the present study was to validate whether fixation and staining treatments are suitable for quantitative transcript expression analysis in laser microdissection (LMD) samples. Quantitative RT-PCR was used to determine the absolute transcript expression levels and profiles of samples obtained from the hippocampal dentate gyrus from fresh frozen mice brain sections that had been fixed with ethanol and stained with NeuroTrace. The results were compared with those obtained from unfixed and unstained samples. Results: We found that the quantitative relationship of transcript expression levels between various housekeeping genes and immediate early genes was preserved, although the preparation compromised the yield of the transcripts. In addition, histological and molecular integrities of the fixed and stained specimens were preserved for at least a week at room temperature. Based on the lobe specific profiles of transcripts in the anterior and posterior lobes of the pituitary, we confirmed that no cross-contamination on transcription expressions occurred as a result of the fixation and staining. Conclusions: We have provided detailed information of the procedures on ethanol fixation followed by NeuroTrace staining on the absolute quantitative RT-PCR analysis using microdissected fresh frozen mouse brain tissues. The present study demonstrated that quantitative transcript expression analysis can be conducted reliably on stained tissues. This method is suitable for applications in basic and clinical studies on particular transcript expressions in various regions of the brain.

    DOI PubMed

  • Developmental changes in the neural responses to own and unfamiliar mother's smiling face throughout puberty

    Tsunehiko Takamura, Shota Nishitani, Takashi Suegami, Hirokazu Doi, Masaki Kakeyama, Kazuyuki Shinohara

    FRONTIERS IN NEUROSCIENCE   9   :200, - (IF=3.877)  2015年06月  [査読有り]

     概要を見る

    An attachment relationship between boys and their mother is important for subsequent development of the ability to sustain peer relationships. Affective responses to attachment figure, especially mother, is supposed to change drastically during puberty. To elucidate the neural correlates underlying this behavioral change, we compared the neural response of boys at three different developmental stages throughout puberty to visual image of their own mothers. Subjects included 27 pre-puberty boys (9.0 +/- 0.6 years), 31 middle puberty boys (13.5 +/- 1.2 years), and 27 post-puberty boys (20.8 +/- 1.9 years), and their mother's smile was video recorded. We measured their neural response in the anterior part of the prefrontal cortex (APFC) to their own mother's smile compared with an unfamiliar-mother's. We found that in response to their own mother's smiling, the right inferior and medial part of the APFC (Ch6) was activated in the pre-puberty group. By contrast, the left inferior and medial (Ch4) and superior (Ch2 and Ch5) APFC were activated in the middle-puberty group, which is presumably linked to empathic feelings fostered by memories of mutual experience with own mother. These findings suggest that different patterns of APFC activation are associated with qualitative changes in affective response to own mother around puberty.

    DOI

  • Environmental insults in early life and submissiveness later in life in mouse models

    Seico Benner, Toshihiro Endo, Masaki Kakeyama, Chiharu Tohyama

    FRONTIERS IN NEUROSCIENCE   9   :91, - (IF=3.877)  2015年03月  [査読有り]

     概要を見る

    Dominant and subordinate dispositions are not only determined genetically but also nurtured by environmental stimuli during neuroendocrine development. However, the relationship between early life environment and dominance behavior remains elusive. Using the IntelliCage-based competition task for group-housed mice, we have previously described two cases in which environmental insults during the developmental period altered the outcome of dominance behavior later in life. First, mice that were repeatedly isolated from their mother and their littermates (early deprivation; ED), and second, mice perinatally exposed to an environmental pollutant, dioxin, both exhibited subordinate phenotypes, defined by decreased occupancy of limited resource sites under highly competitive circumstances. Similar alterations found in the cortex and limbic area of these two models are suggestive of the presence of neural systems shared across generalized dominance behavior.

    DOI

  • げっ歯類を用いた高次脳機能評価法開発と環境化学物質の神経毒性評価への適用.

    日本衛生学雑誌   70:120-126,  2015年

    DOI

  • Early deprivation induces competitive subordinance in C57BL/6 male mice

    Seico Benner, Toshihiro Endo, Nozomi Endo, Masaki Kakeyama, Chiharu Tohyama

    PHYSIOLOGY & BEHAVIOR   137   42 - 52  2014年10月  [査読有り]

     概要を見る

    Rodent models have been widely used to investigate-the impact of early life stress on adult health and behavior. However, the social dimension has rarely been incorporated into the analysis due to methodological limitations. This study characterized the effects of neonatal social isolation (early deprivation, ED) on adult C57BL/6 mouse behavior in a social context using our recently developed behavioral test protocols for group-housed mice. During the first two postnatal weeks, half of the pups per dam were separated from their dam and littermates for 3 h per day (ED group). Post weaning, ED and control pups were electronically tagged and co-housed. At 12 weeks, the mixed cohorts were transferred to IntelliCages, equipped with computer-controlled operant chambers. Access to the chambers was used as an index to analyze novel object response, behavioral flexibility, and competitive dominance with minimal experimenter intervention. In general, ED had greater effects on males; ED males exhibited reduced body weight, increased novelty response, and were subordinate to control littermates when competing for reward access. Male ED mice also demonstrated mildly impaired reversal learning. Analyzing gene expression changes in brain regions controlling emotion, stress, spatial memory, and executive function revealed reduced BDNF and c-Fos in hippocampal CA1, enhanced c-Fos in the basolateral amygdala, reduced Map2 while enhanced HSD11 beta 2 in prefrontal cortex of ED males. In male mice, it was suggested that neonatal social isolation results in sustained changes in social behavior with altered function of limbic and frontal cortices. (C) 2014 The Authors. Published by Elsevier Inc.

    DOI

  • Upregulation of colonic luminal polyamines produced by intestinal microbiota delays senescence in mice

    Ryoko Kibe, Shin Kurihara, Yumi Sakai, Hideyuki Suzuki, Takushi Ooga, Emiko Sawaki, Koji Muramatsu, Atsuo Nakamura, Ayano Yamashita, Yusuke Kitada, Masaki Kakeyama, Yoshimi Benno, Mitsuharu Matsumoto

    SCIENTIFIC REPORTS   4   :4548, - (IF=4.122, cited by 71)  2014年04月  [査読有り]

     概要を見る

    Prevention of quality of life (QOL) deterioration is associated with the inhibition of geriatric diseases and the regulation of brain function. However, no substance is known that prevents the aging of both body and brain. It is known that polyamine concentrations in somatic tissues ( including the brain) decrease with increasing age, and polyamine-rich foods enhance longevity in yeast, worms, flies, and mice, and protect flies from age-induced memory impairment. A main source of exogenous polyamines is the intestinal lumen, where they are produced by intestinal bacteria. We found that arginine intake increased the concentration of putrescine in the colon and increased levels of spermidine and spermine in the blood. Mice orally administered with arginine in combination with the probiotic bifidobacteria LKM512 long-term showed suppressed inflammation, improved longevity, and protection from age-induced memory impairment. This study shows that intake of arginine and LKM512 may prevent aging-dependent declines in QOL via the upregulation of polyamines.

    DOI

  • In utero and lactational exposure to 2,3,7, 8-tetrachlorodibenzo-p-dioxin modulates dysregulation of the lipid metabolism in mouse offspring fed a high-calorie diet

    Etsuko Sugai, Wataru Yoshioka, Masaki Kakeyama, Seiichiroh Ohsako, Chiharu Tohyama

    JOURNAL OF APPLIED TOXICOLOGY   34 ( 3 ) 296 - 306  2014年03月  [査読有り]

     概要を見る

    Exposure to environmental chemicals, including dioxins, is a risk factor for type 2 diabetes mellitus in humans. This study explored the hypothesis that in utero and lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic congener among dioxins, aggravates this disease state later in adulthood. Pregnant C57Bl/6J mice were administered either a single oral dose of TCDD (3.0 mu gkg(-1) body weight) or corn oil on gestational day 12.5. The male pups born to these two groups of dams were given either a regular diet or a high-calorie diet, after postnatal day (PND) 28. The four groups of investigated offspring were thus termed T-R (TCDD regular diet), T-H (TCDD high-calorie diet), V-R (vehicle regular diet), and V-H (vehicle high-calorie diet). The mice were regularly monitored for body weight, blood pressure and glucose, until they reached 26weeks of age. Mice in the V-H group were significantly obese at weeks 15 and 26, but they exhibited no diabetes-associated signs of insulin resistance or hypertension. However, metabolic syndrome-related alterations with marginal signs of liver damage were found at week 26. Pronounced signs of dysregulated lipid metabolism with altered gene expression and liver inflammation were already present at week 15, whereas such alterations were suppressed in the T-H group. Although the mechanism is unclear, this study showed that in utero and lactational exposure to low-dose TCDD does not aggravate obesity-induced disease states, such as adult-onset diabetes, but instead attenuates the dysregulation of lipid metabolism brought on by a high-calorie diet. Copyright (c) 2013 John Wiley & Sons, Ltd.

    DOI

  • Disruption of paired-associate learning in rat offspring perinatally exposed to dioxins

    Masaki Kakeyama, Toshihiro Endo, Yan Zhang, Wataru Miyazaki, Chiharu Tohyama

    ARCHIVES OF TOXICOLOGY   88 ( 3 ) 789 - 798  2014年03月  [査読有り]

     概要を見る

    The prevalence of cognitive abnormalities in children has partly been ascribed to environmental chemical exposure. Appropriate animal models and tools for evaluating higher brain function are required to examine this problem. A recently developed behavioral test in which rats learn six unique flavor-location pairs in a test arena was used to evaluate paired-associate learning, a hallmark of the higher cognitive function that is essential to language learning in humans. Pregnant Long-Evans rats were dosed by gavage with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or 2,3,7,8-tetrabromodibenzo-p-dioxin (TBDD) at a dose of 0, 200, or 800 ng/kg (referred as Control, TCDD-200, TCDD-800, TBDD-200, or TBDD-800, hereafter) on gestational day 15, and the offspring was tested during adulthood. Paired-associate learning was found to be impaired in the TCDD-200 and TBDD-200 groups, but not in either group exposed to 800 ng/kg, the observations of which were ensured by non-cued trials. As for the emotional aspect, during habituation, the TCDD-200 and TBDD-200 groups showed significantly longer latencies to enter the test arena from a start box than the Control, TCDD-800, and TBDD-800 groups, suggesting that the TCDD-200 and TBDD-200 groups manifested anxiety-like behavior. Thus, both the chlorinated dioxin and its brominated congener affected higher brain function to a similar extent in a nearly identical manner. Use of the behavioral test that can evaluate paired-associate learning in rats demonstrated that in utero and lactational exposure to not only TCDD but also TBDD perturbed higher brain function in rat offspring in a nonmonotonic manner.

    DOI

  • Vesicular nucleotide transporter is involved in ATP storage of secretory lysosomes in astrocytes

    Manami Oya, Tetsuya Kitaguchi, Yu Yanagihara, Rika Numano, Masaki Kakeyama, Kazuya Ikematsu, Takashi Tsuboi

    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS   438 ( 1 ) 145 - 151  2013年08月  [査読有り]

     概要を見る

    Recent studies have suggested that astrocytes release gliotransmitters (i.e., ATP, L-glutamate, D-serine, and peptide hormones) and participate actively in synaptic functioning. Although ATP release from astrocytes modulates the activity of neurons, the mechanisms regulating the ATP release from astrocytes and the source of ATP in astrocytes are not well understood. Recently a vesicular nucleotide transporter (VNUT)/solute carrier family 17, member 9 (SLC17A9) has been identified as a mediator of the active accumulation of ATP into vesicles. Here we show by immunocytochemical analysis under confocal microscope and live cell imaging under total internal reflection fluorescence microscope that lysosome-associated VNUT is responsible for ATP release in astrocytes. VNUT was expressed in both primary cultured cortical astrocytes and glioma cell line C6 cells, and mainly localized on lysosome in the cells. We found that VNUT-associated secretory lysosomes do not fully collapse into the plasma membrane after lysosomal exocytosis. We also found that inhibition of VNUT function by Evans Blue decreased ATP uptake into secretory lysosomes. Depletion and inhibition of endogenous VNUT by small interference RNA and Evans Blue, respectively decreased the amount of ATP release from the cells, whereas overexpression of VNUT increased it. Taken together, these findings indicate that the participation of VNUT in ATP storage in secretory lysosomes during lysosomal exocytosis of ATP from astrocytes. (C) 2013 Elsevier Inc. All rights reserved.

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  • Prenatal Exposure to a Polychlorinated Biphenyl (PCB) Congener Influences Fixation Duration on Biological Motion at 4-Months-Old: A Preliminary Study

    Hirokazu Doi, Shota Nishitani, Takashi X. Fujisawa, Tomoko Nagai, Masaki Kakeyama, Takahiro Maeda, Kazuyuki Shinohara

    PLoS ONE   8 ( 3 ) :e59196, - (IF=2.766)  2013年03月  [査読有り]

     概要を見る

    Adverse effects of prenatal exposure to polychlorinated biphenyl (PCB) congeners on postnatal brain development have been reported in a number of previous studies. However, few studies have examined the effects of prenatal PCB exposure on early social development. The present study sought to increase understanding of the neurotoxicity of PCBs by examining the relationship between PCB congener concentrations in umbilical cord blood and fixation patterns when observing upright and inverted biological motion (BM) at four-months after birth. The development of the ability to recognize BM stimuli is considered a hallmark of socio-cognitive development. The results revealed a link between dioxin-like PCB #118 concentration and fixation pattern. Specifically, four-month-olds with a low-level of prenatal exposure to PCB #118 exhibited a preference for the upright BM over inverted BM, whereas those with a relatively high-level of exposure did not. This finding supports the proposal that prenatal PCB exposure impairs the development of social functioning, and indicates the importance of congener-specific analysis in the risk analysis of the adverse effects of PCB exposure on the brain development. © 2013 Doi et al.

    DOI PubMed

  • Executive Function Deficits and Social-Behavioral Abnormality in Mice Exposed to a Low Dose of Dioxin In Utero and via Lactation

    Toshihiro Endo, Masaki Kakeyama, Yukari Uemura, Asahi Haijima, Hiroyuki Okuno, Haruhiko Bito, Chiharu Tohyama

    PLOS ONE   7 ( 12 ) :e50741, - (IF=2.766, cited by 37)  2012年12月  [査読有り]

     概要を見る

    An increasing prevalence of mental health problems has been partly ascribed to abnormal brain development that is induced upon exposure to environmental chemicals. However, it has been extremely difficult to detect and assess such causality particularly at low exposure levels. To address this question, we here investigated higher brain function in mice exposed to dioxin in utero and via lactation by using our recently developed automated behavioral flexibility test and immunohistochemistry of neuronal activation markers Arc, at the 14 brain areas. Pregnant C57BL/6 mice were given orally a low dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at a dose of either 0, 0.6 or 3.0 mu g/kg on gestation day 12.5. When the pups reached adulthood, they were group-housed in IntelliCage to assess their behavior. As a result, the offspring born to dams exposed to 0.6 mu g TCDD/kg were shown to have behavioral inflexibility, compulsive repetitive behavior, and dramatically lowered competitive dominance. In these mice, immunohistochemistry of Arc exhibited the signs of hypoactivation of the medial prefrontal cortex (mPFC) and hyperactivation of the amygdala. Intriguingly, mice exposed to 3.0 mu g/kg were hardly affected in both the behavioral and neuronal activation indices, indicating that the robust, non-monotonic dose-response relationship. In conclusion, this study showed for the first time that perinatal exposure to a low dose of TCDD in mice develops executive function deficits and social behavioral abnormality accompanied with the signs of imbalanced mPFC-amygdala activation.

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  • Fluorescence laser microdissection reveals a distinct pattern of gene activation in the mouse hippocampal region

    Wataru Yoshioka, Nozomi Endo, Akie Kurashige, Asahi Haijima, Toshihiro Endo, Toshiyuki Shibata, Ryutaro Nishiyama, Masaki Kakeyama, Chiharu Tohyama

    SCIENTIFIC REPORTS   2   :783, - (IF=4.122, cited by 12)  2012年11月  [査読有り]

     概要を見る

    A histoanatomical context is imperative in an analysis of gene expression in a cell in a tissue to elucidate physiological function of the cell. In this study, we made technical advances in fluorescence laser microdissection (LMD) in combination with the absolute quantification of small amounts of mRNAs from a region of interest (ROI) in fluorescence-labeled tissue sections. We demonstrate that our fluorescence LMD-RTqPCR method has three orders of dynamic range, with the lower limit of ROI-size corresponding to a single cell. The absolute quantification of the expression levels of the immediate early genes in an ROI equivalent to a few hundred neurons in the hippocampus revealed that mice transferred from their home cage to a novel environment have distinct activation profiles in the hippocampal regions (CA1, CA3, and DG) and that the gene expression pattern in CA1, but not in the other regions, follows a power law distribution.

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  • The small GTPase Cdc42 modulates the number of exocytosis-competent dense-core vesicles in PC12 cells

    Mai Sato, Tetsuya Kitaguchi, Rika Numano, Kazuya Ikematsu, Masaki Kakeyama, Masayuki Murata, Ken Sato, Takashi Tsuboi

    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS   420 ( 2 ) 417 - 421  2012年04月  [査読有り]

     概要を見る

    Although the small GTPase Rho family Cdc42 has been shown to facilitate exocytosis through increasing the amount of hormones released, the precise mechanisms regulating the quantity of hormones released on exocytosis are not well understood. Here we show by live cell imaging analysis under TIRF microscope and immunocytochemical analysis under confocal microscope that Cdc42 modulated the number of fusion events and the number of dense-core vesicles produced in the cells. Overexpression of a wild-type or constitutively-active form of Cdc42 strongly facilitated high-KCl-induced exocytosis from the newly recruited plasma membrane vesicles in PC12 cells. By contrast, a dominant-negative form of Cdc42 inhibited exocytosis from both the newly recruited and previously docked plasma membrane vesicles. The number of intracellular dense-core vesicles was increased by the overexpression of both a wild-type and constitutively-active form of Cdc42. Consistently, activation of Cdc42 by overexpression of Tuba, a Golgi-associated guanine nucleotide exchange factor for Cdc42 increased the number of intracellular dense-core vesicles, whereas inhibition of Cdc42 by overexpression of the Cdc42/Rac interactive binding domain of neuronal Wiskott-Aldrich syndrome protein decreased the number of them. These findings suggest that Cdc42 facilitates exocytosis by modulating both the number of exocytosis-competent dense-core vesicles and the production of dense-core vesicles in PC12 cells. (C) 2012 Elsevier Inc. All rights reserved.

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  • Automated test of behavioral flexibility in mice using a behavioral sequencing task in IntelliCage

    Toshihiro Endo, Fumihiko Maekawa, Vootele Voikar, Asahi Haijima, Yukari Uemura, Yan Zhang, Wataru Miyazaki, Shigetomo Suyama, Kuniko Shimazaki, David P. Wolfer, Toshihiko Yada, Chiharu Tohyama, Hans-Peter Lipp, Masaki Kakeyama

    BEHAVIOURAL BRAIN RESEARCH   221 ( 1 ) 172 - 181  2011年08月  [査読有り]

     概要を見る

    There has been a long-standing need to develop efficient and standardized behavioral test methods for evaluating higher-order brain functions in mice. Here, we developed and validated a behavioral flexibility test in mice using IntelliCage, a fully automated behavioral analysis system for mice in a group-housed environment. We first developed a "behavioral sequencing task" in the IntelliCage that enables us to assess the learning ability of place discrimination and behavioral sequence for reward acquisition. In the serial reversal learning using the task, the discriminated spatial patterns of the rewarded and never-rewarded places were serially reversed, and thus, mice were accordingly expected to realign the previously acquired behavioral sequence. In general, the tested mice showed rapid acquisition of the behavioral sequencing task and behavioral flexibility in the subsequent serial reversal stages both in intra- and inter-session analyses. It was found that essentially the same results were obtained among three different laboratories, which confirm the high stability of the present test protocol in different strains of mice (C57BL/6, DBA/2, and ICR). In particular, the most trained cohort of C578L/6 mice achieved a markedly rapid adaptation to the reversal task in the final phase of the long-term serial reversal test, which possibly indicated that the mice adapted to the "reversal rule" itself. In conclusion, the newly developed behavioral test was shown to be a valid assay of behavioral flexibility in mice, and is expected to be utilized in tests of mouse models of cognitive deficits. (C) 2011 Elsevier B.V. All rights reserved.

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  • Schema-Dependent Gene Activation and Memory Encoding in Neocortex

    Dorothy Tse, Tomonori Takeuchi, Masaki Kakeyama, Yasushi Kajii, Hiroyuki Okuno, Chiharu Tohyama, Haruhiko Bito, Richard G. M. Morris

    SCIENCE   333 ( 6044 ) 891 - 895  2011年08月  [査読有り]

     概要を見る

    When new learning occurs against the background of established prior knowledge, relevant new information can be assimilated into a schema and thereby expand the knowledge base. An animal model of this important component of memory consolidation reveals that systems memory consolidation can be very fast. In experiments with rats, we found that the hippocampal-dependent learning of new paired associates is associated with a striking up-regulation of immediate early genes in the prelimbic region of the medial prefrontal cortex, and that pharmacological interventions targeted at that area can prevent both new learning and the recall of remotely and even recently consolidated information. These findings challenge the concept of distinct fast (hippocampal) and slow (cortical) learning systems, and shed new light on the neural mechanisms of memory assimilation into schemas.

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  • ヒトの健康リスクへの適用を目指した齧歯類を用いる新たな行動毒性試験の開発.

    動物心理学研究   61:33-42,  2011年

    DOI

  • Use of live imaging analysis for evaluation of cytotoxic chemicals that induce apoptotic cell death

    Yoshiko Koike-Kuroda, Masaki Kakeyama, Hidekazu Fujimaki, Shinji Tsukahara

    TOXICOLOGY IN VITRO   24 ( 7 ) 2012 - 2020  2010年10月  [査読有り]

     概要を見る

    We carried out live imaging of PC12 cells expressing SCAT3, a caspase-3 cleavage peptide sequence linking two fluorescent proteins, ECFP and Venus, which function respectively as the donor and acceptor for FRET. Live imaging of SCAT3-expressing cells was performed from 60 to 300 min after exposure to sodium arsenite (NaAsO(2): 0, 1, 5, or 10 mu M) was initiated. We then measured the emission ratio of ECFP to Venus to monitor the activity of caspase-3 and found that the ratio was temporally and dose-dependently increased by NaAsO(2). The mean ECFP/Venus emission ratio between 200 and 300 min after exposure to NaAsO(2) at a dose of 5 or 10 mu M, but not at 1 mu M, was significantly higher than that in the control group. We showed by other methods that NaAsO(2) significantly increased the amount and activity of mature caspase-3 and the amount of nucleosomes generated from DNA fragmentation, and decreased cell viability. However, methods other than live imaging required a longer time and higher doses of NaAsO(2) than did live imaging to detect significant effects. This result suggests that live imaging using SCAT3 is a useful method for the screening of chemical toxicities and for improving the efficiency of toxicity evaluation. (C) 2010 Elsevier Ltd. All rights reserved.

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  • In utero and lactational exposure to low doses of chlorinated and brominated dioxins induces deficits in the fear memory of male mice

    Asahi Haijima, Toshihiro Endo, Yan Zhang, Wataru Miyazaki, Masaki Kakeyama, Chiharu Tohyama

    NEUROTOXICOLOGY   31 ( 4 ) 385 - 390  2010年08月  [査読有り]

     概要を見る

    Environmental-level in utero and lactational exposures to dioxins have been considered to affect brain functions of offspring. Here, we determined whether in utero and lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 2,3,7,8-tetrabromodibenzo-p-dioxin (TBDD), at the dose that does not harm the dams, affects the acquisition and retention of fear memory in mouse offspring. Pregnant C57BL/6J mice were administered by gavages TCDD or TBDD at a dose of 0 or 3.0 mu g/kg body weight on gestation day 12.5, and their male offspring were examined for their behavior in adulthood. In the fear conditioning, a paired presentation of tone and foot shock was repeated three times, and retention tests for contextual and auditory fear memory were carried out 1 and 24 h after the fear conditioning. Groups of mice that were exposed to TCDD and TBDD in utero and via lactation showed deficits in the contextual and auditory retention tests at 1 and 24 h retention intervals. The present results suggest that maternal exposure to a low dose of TCDD or TBDD disrupts the functions of memory and emotion in male mouse offspring, and that the developmental toxicities of these chemicals are similar to each other. (C) 2010 Elsevier Inc. All rights reserved.

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  • Learning behavior in rat offspring after in utero and lactational exposure to either TCDD or PCB126

    Rieko Hojo, Masaki Kakeyama, Yoshika Kurokawa, Yasunobu Aoki, Junzo Yonemoto, Chiharu Tohyama

    Environmental Health and Preventive Medicine   13 ( 3 ) 169 - 180  2008年05月  [査読有り]

     概要を見る

    Objectives: We studied and compared the possible effects of in utero and lactational exposure to 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) or 3, 3', 4, 4', 5-pentachlorobiphenyl (PCB126) on learning behavior in offspring. Methods: Pregnant Long-Evans Hooded rats were administered either TCDD (50, 200, or 800 ng/kg) or PCB126 (500, 2,000 or 8,000 ng/kg) on gestational day 15. A procedure of schedule-controlled operant behavior was applied to examine learning behavior in the male and female offspring at 11 weeks of age for 30 days. Three indices, namely, response rates in a fixed ratio (FR) and in a differential reinforcement of low rates (DRL), and reward rate in the DRL component in multiple FR 20 DRL 20 s (mult-FR 20 DRL 20-s) test sessions, were used for the evaluation of learning behavior. Results: Toxic effects on learning behavior in male and female pups following in utero and lactational exposure to TCDD or PCB126 were observed mainly in the FR learning component. However, no linear dose-dependent effects of either of the two compounds were observed for the above three indices. The response rates of animals in the low-dose TCDD and PCB126 groups decreased and those in medium-dose TCDD and PCB126 groups appeared to induce hyperactive behavior. The high dose of PCB126 appeared to have a distinct toxicity from that of TCDD in terms of the acquisition of learning behavior. Conclusions: Toxicities of PCB126 and TCDD in learning behavior might be similar to each other and the current toxic equivalency factor (TEF) of 0.1 for PCB126 can be considered to be appropriate for this endpoint. © 2008 The Japanese Society for Hygiene.

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  • Perinatal exposure of female rats to 2,3,7,8-tetrachlorodibenzo-p-dioxin induces central precocious puberty in the offspring

    Masaki Kakeyama, Hideko Sone, Chiharu Tohyama

    JOURNAL OF ENDOCRINOLOGY   197 ( 2 ) 351 - 358  2008年05月  [査読有り]

     概要を見る

    Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCED) during the fetal and neonatal periods has been indicated to alter the development of the offspring later in life. In this study, we determined whether perinatal exposure to a low dose of TCDD affects the onset of puberty in the female offspring of Long-Evans hooded rats. On day 15 of gestation, pregnant female rats were administered TCDD by gavage at a single dose of 0 (vehicle), 200, or 800 ng/kg b.xv. In the female offspring born to dams administered with TCDD at either 200 or 800 ng/kg b.w. the vaginal opening and first estrus occurred similar to 4-7 days earlier than in the offspring born to vehicle-treated animals. The ovarian weight gain was also accelerated following exposure to TCDD in a dose-dependent manner. We next examined the ovarian compensatory hypertrophy (OCH) as an indicator of the maturation of the LH/GnRH-generating system in the pituitary and the hypothalamus. Exposure to TCDD accelerated the onset of OCH in the female offspring in a dose-dependent manner. In particular, in the offspring born to the dams exposed to TCDD at 800 ng/kg b.w. hypertrophy, which is characterized by hyperovulation and a marked increase in the weight of the remaining ovary after hemi-ovariectomy, was observed on postnatal days 27-30, which was 10 days earlier than in the offspring born to the vehicle-treated dams. These results indicate that perinatal exposure to a low dose of TCDD induces precocious puberty, including early maturation of the hypothalamic-pituitary axis, the gonads and genitals, in female Long-Evans hooded rats.

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  • Athymic nude mice are insensitive to low-level toluene-induced up-regulation of memory-related gene expressions in the hippocampus

    Tin-Tin Win-Shwe, Shinji Tsukahara, Sohel Ahmed, Atsushi Fukushima, Shoji Yamamoto, Masaki Kakeyama, Daisuke Nakajima, Surnio Goto, Takahiro Kobayashi, Hidekazu Fujimaki

    NEUROTOXICOLOGY   28 ( 5 ) 957 - 964  2007年09月  [査読有り]

     概要を見る

    The function of the N-methyl-D-aspartate (NMDA) subtype of glutamatergic receptors is known to be antagonized by toluene, a well-characterized neurotoxic chemical known to impair memory functions. Recently, peripheral T cells have been clearly shown to play an important role in cognitive and behavioral functions. In the present study, we investigated the role of peripheral T cells in the hippocampal mRNA expression of memory-related genes induced by low levels of toluene exposure in mice. BALB/c wild-type (WT) and nude mice were exposed to 9 ppm of toluene or filtered air (0 ppm toluene; control groups) in a nose-only exposure chamber for 30 min on 3 consecutive days followed by weekly sessions for 4 weeks. Twenty-four hours after the last exposure, the hippocampi were collected and the inducibility of memory-related genes was examined using a real-time quantitative PCR method. NMDA NR2A, calcium/calmodulin-dependent protein kinase IV (CaMKIV), cyclic AMP-responsive element binding protein I (CREB 1), and BDNF were significantly up-regulated in the hippocampi of WT mice exposed to 9 ppm of toluene, compared to the expressions observed in WT mice exposed to filtered air, but similar results were not observed in nude mice. To investigate the possible involvement of peripheral T cells in the toluene-induced up-regulation of memory-related genes in WT mice, we examined the mRNA expression of Thy-1 (a pan T cell-specific marker) and quantified the number of cells that were immunoreactive to a T cell antigen receptor, CD3 (CD3-ir). Both the expression of Thy-1 mRNA and the number of CD3-ir cells were significantly higher in the hippocampi of the WT mice exposed to 9 ppm of toluene, compared with that in WT mice exposed to filtered air; similar results were not observed in nude mice. We also examined the expression of chemokine genes like CCL2 and CCL3. The expression of CCL3 mRNA was significantly up-regulated only in the toluene-exposed WT mice. Although other differences unrelated to immune function may exist between WT and nude mice from the same background, the findings of the present study strongly suggest that the recruitment of peripheral T cells in the hippocampi of BALB/c WT mice exposed to low levels of toluene may be involved in the toluene-induced up-regulation of memory-related genes at the mRNA level. (C) 2007 Elsevier Inc. All rights reserved.

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  • Schemas and memory consolidation

    Dorothy Tse, Rosamund F. Langston, Masaki Kakeyama, Ingrid Bethus, Patrick A. Spooner, Emma R. Wood, Menno P. Witter, Richard G. M. Morris

    SCIENCE   316 ( 5821 ) 76 - 82  2007年04月  [査読有り]

     概要を見る

    Memory encoding occurs rapidly, but the consolidation of memory in the neocortex has long been held to be a more gradual process. We now report, however, that systems consolidation can occur extremely quickly if an associative "schema" into which new information is incorporated has previously been created. In experiments using a hippocampal-dependent paired-associate task for rats, the memory of flavor-place associations became persistent over time as a putative neocortical schema gradually developed. New traces, trained for only one trial, then became assimilated and rapidly hippocampal-independent. Schemas also played a causal role in the creation of lasting associative memory representations during one-trial learning. The concept of neocortical schemas may unite psychological accounts of knowledge structures with neurobiological theories of systems memory consolidation.

    DOI

  • Toluene induces rapid and reversible rise of hippocampal glutamate and taurine neurotransmitter levels in mice

    Tin-Tin Win-Shwe, D. Mitsushima, D. Nakajima, S. Ahmed, S. Yamamoto, S. Tsukahara, M. Kakeyama, S. Goto, H. Fujimaki

    TOXICOLOGY LETTERS   168 ( 1 ) 75 - 82  2007年01月  [査読有り]

     概要を見る

    Toluene. a widely used aromatic organic solvent, has been well characterized as a neurotoxic chemical. Although the neurobehavioral effects of toluene have been studied substantially, the mechanisms involved are not clearly understood. Hippocampus, which is one of the limbic areas of brain associated with neuronal plasticity, and learning and memory functions, may be a principal target of toluene. In the present study, to establish a mouse model for investigating the effects of acute toluene exposure on the amino acid neurotransmitter levels in the hippocampus, in vivo microdialysis study was performed in freely moving mice after a single intraperitoneal administration of toluene (150 and 300 mg/kg,). Amino acid neurotransmitters in microdialysates were measured by a high performance liquid chromatography system. The extracellular levels of glutamate and taurine were rapidly and reversibly increased within 30 min after the toluene administration in a dose-dependent manner and returned to the basal level by 1 h. Conversely, the extracellular level of glycine and GABA were stable, and no significant change was observed after the toluene administration. To further investigate the brain toluene level in the hippocampus of toluene-administered mice, we used a solid-phase microextraction (SPME) method and examined the time course changes of toluene in the hippocampus of living mice. The brain toluene level reached the peak at 30 min after injection and returned to the basal level after 2 h. In the present study, we observed the relationship between brain toluene levels and amino acid neurotransmitter glutamate and taurine levels in the hippocampus. Therefore, we suggest that toluene may mediate its action through the glutamatergic and taurinergic neurotransmission in the hippocampus of freely moving mice. (c) 2006 Published by Elsevier Ireland Ltd.

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  • Sex differences in the level of Bcl-2 family proteins and caspase-3 activation in the sexually dimorphic nuclei of the preoptic area in postnatal rats

    Shinji Tsukahara, Masaki Kakeyama, Yuki Toyofuku

    JOURNAL OF NEUROBIOLOGY   66 ( 13 ) 1411 - 1419  2006年11月  [査読有り]

     概要を見る

    In developing rats, sex differences in the number of apoptotic cells are found in the central division of the medial preoptic nucleus (MPNc), which is a significant component of the sexually dimorphic nucleus of the preoptic area, and in the anteroventral periventricular nucleus (AVPV). Specifically, male rats have more apoptotic cells in the developing AVPV, whereas females have more apoptotic cells in the developing MPNc. To determine the mechanisms for the sex differences in apoptosis in these nuclei, we compared the expression of the Bcl-2 family members and active caspase-3 in postnatal female and male rats. Western blot analyses for the Bcl-2 family proteins were performed using preoptic tissues isolated from the brain on postnatal day (PD) 1 (day of birth) or on PD8. In the AVPV-containing tissues of PD1 rats, there were significant sex differences in the level of Bcl-2 (female > male) and Bax (female < male) proteins, but not of Bcl-xL or Bad proteins. In the MPNc-containing tissues of PD8 rats, there were significant sex differences in the protein levels for Bcl-2 (female < male), Bax (female > male), and Bad (female < male), but not for Bcl-xL. Immunohistochemical analyses showed significant sex differences in the number of active caspase-3-immunoreactive cells in the AVPV on PD1 (female < male) and in the MPNc on PD8 (female > male). We further found that active caspase-3-immunoreactive cells of the AVPV and MPNc were immunoreactive for NeuN, a neuronal marker. These results suggest that there are sex differences in the induction of apoptosis via the mitochondrial pathway during development of the AVPV and MPNc. (c) 2006 Wiley Periodicals, Inc.

    DOI

  • Determination of toluene in brain of freely moving mice using solid-phase microextraction technique

    Daisuke Nakajima, Tin-Tin-Win-Shwe, Masaki Kakeyama, Hidekazu Fujimaki, Sumio Goto

    NEUROTOXICOLOGY   27 ( 4 ) 615 - 618  2006年07月  [査読有り]

     概要を見る

    For the purpose of measuring the pharmacokinetics of inhaled toluene in the brain of mice, we developed a method for the direct detection of toluene by gas chromatography/mass spectrometry (GUMS). The method uses a solid-phase microextraction (SPME) fiber inserted into the mouse' hippocampus (CA1) through a cannula fixed onto the animal. BALB/c mice were exposed to 0, 0.9, 9, 50 and 90 ppm toluene for 30 min. The toluene level detected near the hippocampus by this method after exposure to 0.9 ppm toluene in air showed no significant difference from the level found in the non-exposure control group; however, the toluene level increased significantly after exposure to concentrations of 9, 50 and 90 ppm. These increases were concentration-dependent. In addition, the pharmacokinetics of toluene in the brain of mice exposed to 50 ppm toluene showed that the toluene level decreased rapidly after the exposure, and returned to control levels after 60 min. This study describes the method which has successfully detected toluene levels in the brain of conscious, free-moving mice for the first time. (c) 2006 Elsevier Inc. All rights reserved.

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  • Brain cytokine and chemokine mRNA expression in mice induced by intranasal instillation with ultrafine carbon black

    Tin-Tin-Win-Shwe, S Yamamoto, S Ahmed, M Kakeyama, T Kobayashi, H Fujimaki

    TOXICOLOGY LETTERS   163 ( 2 ) 153 - 160  2006年05月  [査読有り]

     概要を見る

    Ambient air ultrafine particles (UFPs) have gained enormous attention to many researchers with recent evidence showing them to have more hazardous effects on human health than larger ambient particles. Studies focusing the possibility of effects on brain are quite limited. To examine the effect of ultrafine carbon black (ufCB) on mice brain, we instilled 125 mu g of 14 nm or 95 nm CB into the nostrils of 8-week-old male BALB/c mice, once a week for 4 weeks. Four hours after the last instillation, we collected olfactory bulb and hippocampus and detected the expression of cytokine and chemokine mRNA by quantitative real-time PCR method. In this study, we found the induction of proinflammatory cytokines (interleukin-1 beta and tumor necrosis factor-alpha and chemokines (monocyte chemoattractant protein-1/CCL2, macrophage inflammatory protein-1 alpha/CCL3), and monokine induced interferon-gamma/CXC chemokine ligand (CXCL9) mRNA in brain olfactory bulb, not in the hippocampus of mice instilled with 14 nm ufCB intranasally. We suggest that the intranasal instillation of ufCB may influence the brain immune function depending on their size. To our knowledge, this is the first study to demonstrate region-specific brain cytokine and chemokine mRNA-induction in mice triggered by intranasal instillation of specific-sized ufCB, in a physiologically relevant condition. (c) 2005 Elsevier Ireland Ltd. All rights reserved.

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  • Effect of intratracheal instillation of ultrafine carbon black on proinflammatory cytokine and chemokine release and mRNA expression in lung and lymph nodes of mice

    Tin-Tin-Win-Shwe, S Yamamoto, M Kakeyama, T Kobayashi, H Fujimaki

    TOXICOLOGY AND APPLIED PHARMACOLOGY   209 ( 1 ) 51 - 61  2005年11月  [査読有り]

     概要を見る

    Our understanding of how ultrafine particles, which are Constituents of particulate matter, affect immunological response is poor. To investigate the size-specific effect of ultrafine particles on pulmonary immune responses, translocation to lymph nodes, and chemokine mRNA expressions in lung and lymph nodes, we performed three experiments in 8-week-old male BALB/c mice. In experiment 1, we instilled 25 mu g, 125 mu g or 625 mu g of 14 nm carbon black (CB) particles intratracheally, once weekly for 4 weeks, and in experiment 2, we instilled 95 nm CB. For detection of total and differential Cell Counts and cytokine and chemokine protein release, we collected bronchoalveolar lavage (BAL) fluid 24 h after the last instillation of CB. Experiments 1 and 2 showed that 125 mu g was the Suitable dose for experiment 3, which we then performed on the same schedule and 4 h after the last instillation, we harvested the lung and mediastinal lymph node to detect chemokine mRNA expression by real-time RT-PCR. The total cell Count as well as the differential cell Counts Such as macrophages, lymphocytes, and neutrophils in BAL fluid increased significantly in mice exposed to 14 nm CB in a dose-dependent manner. Release of cytokines such as interleukin (IL)-1 beta, IL-6, and tumor necrosis factor-alpha increased significantly in BAL fluid in mice instilled with 14-nm CB. Macrophage inflammatory protein 1 alpha/CCL-3 protein and mRNA expression were increased significantly in the lungs and lymph nodes of mice given 14 nm CB. Histologically, deposition of CB was observed greater in the mediastinal lymph nodes of mice given 14 run than in 95 nm CB. These findings indicate that repeated intratracheal instillation Of Ultrafine carbon black in mice leads to pulmonary inflammation, their translocation to mediastinal lymph nodes and increased chemokine rnRNA expression in lung and lymph nodes size-specifically. (c) 2005 Elsevier Inc. All rights reserved.

    DOI

  • In utero and lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin in rats disrupts brain sexual differentiation

    M Ikeda, T Mitsui, K Setani, M Tamura, M Kakeyama, H Sone, C Tohyama, T Tomita

    TOXICOLOGY AND APPLIED PHARMACOLOGY   205 ( 1 ) 98 - 105  2005年05月  [査読有り]

     概要を見る

    The effects of in utero and lactational exposure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on brain sexual differentiation were investigated. TCDD was orally administered to pregnant Holtzman rats on gestation day (GD) 15, and the activity of brain aromatase, a key enzyme for sexual differentiation, was measured in offspring on postnatal day (PND) 2. Changes in sexual dimorphisms of saccharin preference and the volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) were examined in adult offspring. In controls, litter means of brain aromatase activity were higher in males than in females. In utero exposure to 200 ng/kg TCDD significantly decreased the sex ratio of aromatase activity (male/female) on PND 2. Offspring were weaned on PND28 and the saccharin test was started on PND84. In controls, saccharin (0.25%) intake (g/kg body weight) was significantly higher in female offspring than in males. In utero exposure to 200 ng/kg TCDD significantly increased saccharin intake in male offspring compared with control males, whereas 800 ng/kg TCDD had no effect. Neither dose of TCDD influenced saccharin intake of female offspring. In controls, SDN-POA volume was significantly greater in males than in females at 14 weeks of age. Exposure to 200 ng/kg TCDD significantly decreased SDN-POA volume in males, whereas 800 ng/kg TCDD had no effect. Neither doses of TCDD influenced the SDN-POA volume in female offspring. These results suggest that in utero and lactational TCDD exposure dose-dependently induces demasculinization in male offspring by inhibiting brain aromatase activity in the hypothalamus preoptic area during central nervous system development. (c) 2004 Elsevier Inc. All rights reserved.

    DOI

  • Postnatal apoptosis, development and sex difference in the lateral septum of rats.

    Tsukahara S, Inami K, Maekawa F, Kakeyama M, Yokoyama T, Yuji M, Kitagawa Y, Yamanouchi K

    Journal of Comparative Neurology   475   :177-187, - (IF=3.4, cited by 18)  2004年  [査読有り]

    DOI

  • Perinatal exposure to dioxins perturbs learning performance of the rat in a dose-specific fashion.

    Hojo R, Kakeyama M, Yonemoto J, Tohyama C

    Organohalogen Compounds   66   :3143 - 3147,  2004年  [査読有り]

  • Haxachlorobiphenyl (PCB153) impairs learning performance in rat offspring.

    Hojo R, Kakeyama M, Yonemoto J, Tohyama C

    Organohalogen Compounds   67   :2394 - 2395,  2004年  [査読有り]

  • Inhalation of low-level formaldehyde enhances nerve growth factor production in the hippocampus of mice

    H Fujimaki, Y Kurokawa, M Kakeyama, N Kunugita, Y Fueta, T Fukuda, H Hori, K Arashidani

    NEUROIMMUNOMODULATION   11 ( 6 ) 373 - 375  2004年  [査読有り]

     概要を見る

    Objective: The effects of low-level formaldehyde ( FA) inhalation on the amount of nerve growth factor (NGF) in the hippocampus of immunized mice were studied. Methods: Evaluation of NGF in the hippocampus was performed by ELISA and RT-PCR. Results: Exposure to 80 and 400 ppb FA significantly increased the brain NGF levels in the immunized mice. Evaluation of the NGF levels in the hippocampus of immunized mice showed that 400 ppb FA significantly increased the NGF content. The RT-PCR evaluation also showed higher concentrations of hippocampal NGF mRNA in the mice exposed to 80 and 400 ppb FA with immunization. Conclusion: Exposure of immunized mice to low levels of FA significantly increases NGF levels in the hippocampus. Copyright (C) 2004 S. Karger AG, Basel.

    DOI

  • Perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin alters activity-dependent expression of BDNF mRNA in the neocortex and male rat sexual behavior in adulthood

    M Kakeyama, H Sone, Y Miyabara, C Tohyama

    NEUROTOXICOLOGY   24 ( 2 ) 207 - 217  2003年03月  [査読有り]

     概要を見る

    Dioxin and its related compounds are suspected to cause neurological and nueroendocrinological disruption in human and laboratory animal offspring upon in utero and lactational exposure during growth and development. We tested the hypothesis by utilizing Long-Evans Hooded rats that perinatal exposure to dioxins affects the neocortical function and expression of sexual behavior in adulthood. In the sexual behavior test, perinatal exposure to TCDD significantly reduced the number of mounts and intromissions. The mRNA semi-quantification in in situ hybridization showed that the mating stimulus in control males induced c fos mRNA expression in the preoptic area (POA) and the brain derived neurotrophic factor (BDNF) mRNA upregulation in the frontal cortex. In contrast, perinatal exposure to TCDD lowered the upregulation of BDNF mRNA in the frontal cortex but not that of c fos mRNA in the POA. The volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) was not affected. The results suggest that perinatal TCDD affects the neocortical function independently from the brain sexual differentiation and alters the expression of sexual behavior. (C) 2002 Elsevier Science Inc. All rights reserved.

    DOI

  • Developmental neurotoxicity of dioxin and its related compounds.

    Kakeyama M, Tohyama C

    Industrial Health   41   :215-230, - (IF=1.115, cited by 64)  2003年  [査読有り]

    DOI

  • Decrease of serotonin and metabolite in the forebrain and facilitation of lordosis by dorsal raphe nucleus lesions in male rats.

    Kakeyama M, Umino A, Nishikawa T, Yamanouchi K

    Endocrine Journal   1   .49:573-579, - (IF=1.911, cited by 13)  2002年  [査読有り]

    DOI

  • Developmental stage-specific effects of perinatal 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure on reproductive organs of male rat offspring.

    Ohsako S, Miyabara Y, Sakaue M, Ishimura R, Kakeyama M, Izumi H, Yonemoto J, Tohyama C

    Toxicological Sciences   66   :283-292, - (IF=4.181, cited by 77)  2002年  [査読有り]

    DOI

  • Estrogen potentiates N-methyl-D-aspartate receptor subnunit R2B mRNA expression during the late prepubertal period in female rats.

    Kanamaru H, Kakeyama M, Seki T, Arai Y

    Neuroscience Letters   300   , 9-12, - (IF=2.159, cited by 8)  2001年  [査読有り]

    DOI

  • Changes in expression of NMDA receptor subunit mRNA by perinatal exposure to dioxin.

    Kakeyama M, Sone H, Tohyama C

    NeuroReport   21   :4009-4012, - (IF=1.266, cited by 40)  2001年  [査読有り]

  • NMDA受容体サブユニットmRNAに対するアンチセンスオリゴヌクレオチドによるmethamphetamine逆耐性現象の形成阻害.

    精神薬療基金研究年報   29: 32-36,  1998年

  • Facilitatory effect of ventral cut of dorsal raphe nucleus on lordosis in female rats.

    Kakeyama M, Negishi M, Yamanouchi K

    Endocrine Journal   44   : 589-593, - (IF=1.911, cited by 15)  1997年  [査読有り]

    DOI

  • Lordosis in male rats: Effect of dorsal raphe nucleus cuts

    Masaki Kakeyama, Korehito Yamanouchi

    Hormones and Behavior   32 ( 1 ) 60 - 67  1997年  [査読有り]

     概要を見る

    The efferents and/or afferents of the dorsal raphe nucleus (DRN) were transected by several types of cut in castrated male rats, and lordosis behavior was observed after implantation with Silastic tubes containing estradiol. Throughout the behavioral tests, low incidences of lordosis were observed in control male rate without brain surgery or with a sham operation. In contrast, all male rats with a horizontal circle cut at the ventral area of the DRN displayed lordosis, and the mean lordosis quotient (LQ) was higher than that in control rats, while rats with a horizontal cut at the dorsal area of the DRN did not. Furthermore, mean LQs in male rats with an anterior half-circle horizontal cut at the ventral area of the DRN were higher than those in control groups. A posterior half-circle cut at the ventral area had no effect. In addition, male rats with a half-dome cut located anterior to the DRN showed a high LQ score, but rats with a posterior half-dome cut did not. These results suggest that anterior and anteroventral neural fibers of the DRN are involved in the lordosis inhibiting mechanism in male rats.

    DOI PubMed

  • Inhibitory effect of baclofen on lordosis in female and male rats with dorsal raphe nucleus lesion or septal cut.

    Kakeyama M, Yamanouchi K

    Neuroendocrinology   63   :293-296, - (IF=5.204, cited by 31)  1996年  [査読有り]

    DOI

  • Functional relationships between mesencephalic central gray and septum in regulating lordosis in female rats: Effect of dual lesions.

    Kondo Y, Koizumi T, Arai Y, Kakeyama M, Yamanouchi K

    Brain Research Bulletin   32   :635-638, - (IF=2.517, cited by 18)  1994年  [査読有り]

  • 縫線核と生殖生理.

    ヒューマンサイエンス   7:78-91, (査読有)  1994年

  • Two types of lordosis inhibiting systems in male rats: Dorsal raphe nucleus lesions and septal cuts.

    Kakeyama M, Yamanouchi K

    Physiology & Behavior   56   :189-192, - (IF=2.517, cited by 18)  1994年  [査読有り]

  • 雄ラットにおける雌型性行動神経制御機構:中脳背側縫線核の役割.

    ヒューマンサイエンス・リサーチ   2:73-87,  1993年

  • Female sexual behaviors in male rats with dorsal raphe nucleus lesions: Treatment with p-chlorophenylalanine.

    Kakeyama M, Yamanouchi K

    Brain Research Bulletin   30   :705-709, - (IF=3.440)  1993年  [査読有り]

  • Lordosis in male rats: The facilitatory effect of mesencephalic dorsal raphe nucleus lesion.

    Kakeyama M, Yamanouchi K

    Physiology & Behavior   51   :181-184, - (IF=2.517, cited by 26)  1992年  [査読有り]

  • Effect of medullary raphe lesions on sexual behavior in male rats with or without treatments of p-chlorophenylalanine.

    Yamanouchi K, Kakeyama M

    Physiology & Behavior   51   :575-579, - (IF=2.517, cited by 20)  1992年  [査読有り]

▼全件表示

受賞

  • 日本衛生学会奨励賞

    2012年03月  

  • 早稲田大学小野梓記念賞学術賞

    1992年03月  

共同研究・競争的資金等の研究課題

  • ヒトGWASデータに基づいたAhr発達神経毒性の分子機構の解明

    科学研究費助成事業(長崎大学)  科学研究費助成事業(基盤研究(A))

    研究期間:

    2014年
    -
    2016年
     

  • 定量的行動試験をもとにした顕微鏡解析による発達神経毒性の分子標的の同定

    科学研究費助成事業(東京大学)  科学研究費助成事業(若手研究(S))

    研究期間:

    2009年
    -
    2013年
     

     概要を見る

    化学物質の曝露影響のなかでも、母体にはなんら影響が顕われない極めて低用量の曝露が脳発達に及ぼす影響をターゲットとして、定量的行動試験をもとにした顕微鏡解析により、毒性の有無と分子標的の同定を目指した。ダイオキシン等の環境化学物質の胎仔期低用量曝露が皮質-皮質下機能アンバランスを引き起こし、認知学習から社会性行動、問題行動に至る行動異常を表出することを明らかにし、その分子標的候補を同定した。

  • 多環芳香族炭化水素化合物のAh受容体を介した発達神経毒性メカニズムの解明

    科学研究費助成事業(東京大学)  科学研究費助成事業(基盤研究(B))

    研究期間:

    2009年
    -
    2011年
     

     概要を見る

    多環芳香族炭化水素(PAHs)は環境中に蓄積し、ヒトは食品や環境媒体を介して体内に取り込んでいる。本研究では、妊娠期のPAHsへの曝露が、成長後の子の学習・情動機能に及ぼす影響とその毒性発現メカニズムを、マウスを用いたin vivo行動試験により解明することを目的とした。その結果、Ah受容体そのものが行動異常の責任分子である可能性が示された。脳機能におけるAh受容体の生物学的意義について、今後さらに研究を進める必要がある。

  • 新たな連合学習試験法による化学物質曝露と軽度発達障害の因果関係解析

    科学研究費助成事業(東京大学)  科学研究費助成事業(若手研究(A))

    研究期間:

    2006年
    -
    2008年
     

     概要を見る

    発達期の脳は脆弱であり、化学物質影響科学のターゲットとして極めて重要である。ラットにおいて連合学習と行動異常の両面を検出する新たな行動毒性試験法を確立し、ダイオキシン等環境化学物質の低用量曝露を陽性条件として、胎児期から出生直後にかけての環境中有害化学物質が高次脳機能の発達に及ぼす影響について解析した。ダイオキシン等化学物質の比較的低用量の曝露により、軽度発達障害を引き起こす可能性が示唆された。

  • ダイオキシンとポリ塩素化ビフェニル複合曝露による毒性の遺伝子プロファイルの作成

    科学研究費助成事業(独立行政法人国立環境研究所)  科学研究費助成事業(基盤研究(A))

    研究期間:

    2003年
    -
    2006年
     

     概要を見る

    ダイオキシン類として行政的に規制をされている物質群は、ダイオキシン、ジベンゾフラン、平面構造を有するPCB(いわゆるコプラナーPCB)である。その理由は、これらの化学物質が、ダイオキシン異性体の中でもっとも毒性が強い2,3,7,8-TCDD(以下、TCDDと略す)がアリール炭化水素受容体(AhR)を介して示す毒性と同じ毒性を表わすことが前提となっている。しかし、環境から同時に曝露するこれらの化合物および非コプラナーPCBの複合曝露による影響と毒性メカニズムはほとんど解明されていない。そこで本研究は、実験動物に対してTCDDとPCBの複合曝露を行い、複合曝露に伴うAhR依存性と非依存性に現れる毒性の量・反応関係を明らかにし、遺伝子プロファイル解析により毒性発現メカニズムの分子基盤に関わる情報を提示することを目的として行った。研究成果として、第一に、極めて低用量のTCDD単独曝露(妊娠15日目の母動物に50ng/kgを単回経口投与)により有意な学習行動低下があること、第

  • 低濃度ホルムアルデヒド曝露によるマウス脳の遺伝子発現変動の解析

    科学研究費助成事業(独立行政法人国立環境研究所)  科学研究費助成事業(若手研究(B))

    研究期間:

    2003年
    -
    2004年
     

     概要を見る

    ホルムアルデヒド(FA)が原因の一つであると指摘されている化学物質過敏症(CS)の場合、患者本人も気づかないような極めて低濃度の曝露でも影響が現れることが示唆されている(本研究計画は疾病の定義づけを目的としたものではないので、極めて低濃度の化学物質に反応する病態について、広い範囲で含めたものをCSと表現する)。CSは一般的にアレルギー反応の一種のように考えられがちだが、その主症状は不定愁訴であり脳神経系に由来すると思われる。そこで本年度は、CSの発症と症状の双方に脳神経系が関わると仮説をたて、環境基準値とほぼ同等である低濃度のFAを断続的かつ長期間曝露し、脳の遺伝子発現変動を解析した。慢性ガス曝露チャンバーを用い、FAの低濃度長期間曝露をマウスに対して行い、脳および免疫系組織(脾臓、胸腺)をサンプリングした。大脳新皮質、海馬、線条体、視床下部からRNAを抽出し、mRNA発現量をサーマルサイクラーを用い半定量的RT-PCR法により半定量

▼全件表示

特定課題研究

  • マウス社会的競争環境課題の最適化

    2018年  

     概要を見る

    自閉スペクトラム関連症状を想定してマウス実験で広く用いられている行動テストを概観し、また我々の新たな行動テストについても触れながら、マウスの行動表現型や行動指標が精神医学上、はたしてヒトに外挿できるかどうかについて検討した。そして、マウスの意識レベルでの行動柔軟性を定量化する行動テスト、競争状態でマウスがみせる行動パターンを定量化する行動テストの最適化を行った。本研究の成果をもとに、2019年度AMED革新脳プロジェクトに採択された。

  • ダイオキシン毒性に基づく社会行動異常マーカーの同定

    2018年  

     概要を見る

    成人には影響の顕れない低用量の化学物質曝露が子どもの精神神経発達に影響を及ぼすという懸念が高まる中、環境脳科学研究室では、ダイオキシン類は自閉スペクトラム症(ASD)当事者に類似の精神神経発達の異常を引き起こすことを明らかにしてきた。 本研究では、曝露動物とヒトASD当事者の比較解析により、低用量ダイオキシンの胎児期・授乳期曝露によって生じる「社会行動異常」の血液中バイオマーカーの解析を行った。この成果をもとに、科研費挑戦的研究(開拓)に申請を行った。

  • 神経活動と行動表現型による神経毒性評価

    2018年  

     概要を見る

    これまでに動物実験により、残留性有機汚染物質(POPs)は極めて低用量で精神神経発達に影響を及ぼすことを明らかにしてきた。本研究では、動物行動試験のヒトへの外挿性の向上を目指し、自ら開発した自動行動試験にリアルタイム神経活動解析の実装を行なった。課題遂行中の行動と神経活動の変化を自動取得し、行動と神経活動の定量データを客観的に結びつけることが期待される。本研究をもとに、2019年度科研費基盤研究(A)に採択された。

  • 競争環境における「個性スペクトラム」の分子神経基盤

    2017年  

     概要を見る

    マウスなどの社会行動試験では1ないし2匹の刺激マウスを提示し、被験マウスの解析を行うといった限定的な解析が大多数を占めており、社会的個性やそのスペクトラムの生物学的基盤に関する研究は極めて乏しい。そこで我々はこれまでに、IntelliCage全自動行動解析システムを用い、14~16匹のマウスを集団生活させた状態で水飲み場を取り合わせるという、いわば「椅子取りゲーム」をマウスで行う社会的競争課題を開発した。本研究では、この社会的競争環境課題における行動成績と神経活動との対応について検討し、競争環境課題に関わる脳領域について明らかにすることができた。

  • 向社会性ハタネズミの表情識別能力の検証

    2017年  

     概要を見る

    我々は小動物用のTouch Screen型の視覚学習装置を新たに作製した。この装置を用いることで、例えば「K」と「M」の二つの図形を提示し、正解の図形を選ばせるといった図形弁別課題において、マウスは約1週間で90%超の正答率を示すことができる。本研究では、 voleにおける試験系を確立した。表情や個体を視覚刺激として用いることで、視覚刺激に対して反応し報酬をうるという課題を1時間に数百回行うようvoleをトレーニングし、視覚能力について調べることができた。

  • マウス競争環境モデルにおける環境要因による精神病態行動表現型の同定

    2015年  

     概要を見る

    精神疾患(類似症状を含む)の表現型発現において、環境要因の寄与度は従来考えられていた以上に重みをもつことが明らかとなってきた。「社会性がない」と思われてきたマウスにおいても、例えば実験的に幼若期における社会環境操作(母子分離や社会環境隔離)を処置することで将来の行動や脳活動の異常が引き起こされることが示され、従来の考えを覆すほど、社会的ストレスの影響を再現しうることが明らかとなりつつある。本研究課題では、環境要因ならびに遺伝要因にもとづく複数の社会行動異常モデルマウスを用い、行動レベルで精神病態の表現型について解析を行い、社会環境隔離と母子分離の行動表現型に違いがあることを明らかにした。

  • 個体間相互作用における最初期遺伝子群の発現量モデル

    2015年  

     概要を見る

    ヒトが他個体を認知する際、脳の中でも前頭前皮質(PFC)の活動が高くなることが知られている。また、自閉スペクトラム症当事者のように他個体への関心が低いケースでは、PFCの活動強度が低い。マウスにおいても類似の表現型を持つことが明らかになった(マウスPFCも社会的場面で高活動を示し、社会的場面を避ける行動表現型をもつモデルマウスではPFC活動強度が低いことを確認した)。他個体との関係性を築いていく時、ヒトにもマウスにも共通する「個体間相互作用の生命原理」がPFCに存在する可能性があり、我々のマウス実験系において、高度な社会における「個体間相互作用の生命原理」を一定の範囲で解明できると考えられる。

  • ヒト研究とマウス実験の融合による低用量曝露における発達神経毒性の評価尺度の開発

    2015年  

     概要を見る

    発達期の環境要因が精神疾患の発症・増悪に寄与するという知見が集積されている。環境要因の中でも親子関係をはじめとした社会的生育環境が重要なことは言うまでもない。本研究では、我々がダイオキシン曝露影響の解明のために開発してきたマウス高次脳機能評価手法を用い、さまざまな遺伝要因や生育環境要因について検討してきた結果に関するメタ解析を行い、高次脳機能の健康な発達に影響を及ぼす阻害要因について検討した。その結果、脳全体の神経ネットワーク異常の結果として前頭前皮質機能が低下することが示唆された。脳全体の神経ネットワークを捉えるような構成的アプローチが必要であると考えられる。

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