2021/10/05 更新

写真a

マエジマ ショウ
前嶋 翔
MAEJIMA Shou
所属
自然科学学域 助教(特任)
職名
助教(特任)
外部リンク

学位

  • 博士(理学) ( 富山大学 )

研究キーワード

  • 生殖

  • 浸透圧調節

  • 比較内分泌

  • エネルギー代謝

  • 神経内分泌

研究分野

  • ライフサイエンス / 形態、構造

  • ライフサイエンス / 神経科学一般

  • ライフサイエンス / 実験動物学

  • ライフサイエンス / 動物生理化学、生理学、行動学

学歴

  • 富山大学大学院   理工学教育部博士課程   地球生命環境科学専攻

    2009年4月 - 2012年3月

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経歴

  • 岡山大学   理学部附属牛窓臨海実験所   助教

    2019年2月 - 現在

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  • 埼玉大学大学院   理工学研究科   博士研究員

    2014年5月 - 2019年1月

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  • 広島大学大学院   総合科学研究科   博士研究員

    2012年4月 - 2014年5月

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  • 日本学術振興会   特別研究員

    2009年4月 - 2012年3月

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所属学協会

▼全件表示

 

論文

  • Immunoelectron Microscopic Characterization of Vasopressin-Producing Neurons in the Hypothalamo-Pituitary Axis of Non-Human Primates by Use of Formaldehyde-Fixed Tissues Stored at -25 °C for Several Years. 国際誌

    Akito Otubo, Sho Maejima, Takumi Oti, Keita Satoh, Yasumasa Ueda, John F Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

    International journal of molecular sciences   22 ( 17 )   2021年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Translational research often requires the testing of experimental therapies in primates, but research in non-human primates is now stringently controlled by law around the world. Tissues fixed in formaldehyde without glutaraldehyde have been thought to be inappropriate for use in electron microscopic analysis, particularly those of the brain. Here we report the immunoelectron microscopic characterization of arginine vasopressin (AVP)-producing neurons in macaque hypothalamo-pituitary axis tissues fixed by perfusion with 4% formaldehyde and stored at -25 °C for several years (4-6 years). The size difference of dense-cored vesicles between magnocellular and parvocellular AVP neurons was detectable in their cell bodies and perivascular nerve endings located, respectively, in the posterior pituitary and median eminence. Furthermore, glutamate and the vesicular glutamate transporter 2 could be colocalized with AVP in perivascular nerve endings of both the posterior pituitary and the external layer of the median eminence, suggesting that both magnocellular and parvocellular AVP neurons are glutamatergic in primates. Both ultrastructure and immunoreactivity can therefore be sufficiently preserved in macaque brain tissues stored long-term, initially for light microscopy. Taken together, these results suggest that this methodology could be applied to the human post-mortem brain and be very useful in translational research.

    DOI: 10.3390/ijms22179180

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  • Variation of pro-vasopressin processing in parvocellular and magnocellular neurons in the paraventricular nucleus of the hypothalamus: Evidence from the vasopressin-related glycopeptide copeptin. 国際誌

    Natsuko Kawakami, Akito Otubo, Sho Maejima, Ashraf H Talukder, Keita Satoh, Takumi Oti, Keiko Takanami, Yasumasa Ueda, Keiichi Itoi, John F Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

    The Journal of comparative neurology   529 ( 7 )   1372 - 1390   2021年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Arginine vasopressin (AVP) is synthesized in parvocellular- and magnocellular neuroendocrine neurons in the paraventricular nucleus (PVN) of the hypothalamus. Whereas magnocellular AVP neurons project primarily to the posterior pituitary, parvocellular AVP neurons project to the median eminence (ME) and to extrahypothalamic areas. The AVP gene encodes pre-pro-AVP that comprises the signal peptide, AVP, neurophysin (NPII), and a copeptin glycopeptide. In the present study, we used an N-terminal copeptin antiserum to examine copeptin expression in magnocellular and parvocellular neurons in the hypothalamus in the mouse, rat, and macaque monkey. Although magnocellular NPII-expressing neurons exhibited strong N-terminal copeptin immunoreactivity in all three species, a great majority (~90%) of parvocellular neurons that expressed NPII was devoid of copeptin immunoreactivity in the mouse, and in approximately half (~53%) of them in the rat, whereas in monkey hypothalamus, virtually all NPII-immunoreactive parvocellular neurons contained strong copeptin immunoreactivity. Immunoelectron microscopy in the mouse clearly showed copeptin-immunoreactivity co-localized with NPII-immunoreactivity in neurosecretory vesicles in the internal layer of the ME and posterior pituitary, but not in the external layer of the ME. Intracerebroventricular administration of a prohormone convertase inhibitor, hexa-d-arginine amide resulted in a marked reduction of copeptin-immunoreactivity in the NPII-immunoreactive magnocellular PVN neurons in the mouse, suggesting that low protease activity and incomplete processing of pro-AVP could explain the disproportionally low levels of N-terminal copeptin expression in rodent AVP (NPII)-expressing parvocellular neurons. Physiologic and phylogenetic aspects of copeptin expression among neuroendocrine neurons require further exploration.

    DOI: 10.1002/cne.25026

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  • Vasopressin gene products are colocalised with corticotrophin-releasing factor within neurosecretory vesicles in the external zone of the median eminence of the Japanese macaque monkey (Macaca fuscata). 国際誌

    Akito Otubo, Natsuko Kawakami, Sho Maejima, Yasumasa Ueda, John F Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

    Journal of neuroendocrinology   32 ( 8 )   e12875   2020年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Arginine vasopressin (AVP), when released into portal capillaries with corticotrophin-releasing factor (CRF) from terminals of parvocellular neurones of the hypothalamic paraventricular nucleus (PVH), facilitates the secretion of adrenocorticotrophic hormone (ACTH) in stressed rodents. The AVP gene encodes a propeptide precursor containing AVP, AVP-associated neurophysin II (NPII), and a glycopeptide copeptin, although it is currently unclear whether copeptin is always cleaved from the neurophysin and whether the NPII and/or copeptin have any functional role in the pituitary. Furthermore, for primates, it is unknown whether CRF, AVP, NPII and copeptin are all colocalised in neurosecretory vesicles in the terminal region of the paraventricular CRF neurone axons. Therefore, we investigated, by fluorescence and immunogold immunocytochemistry, the cellular and subcellular relationships of these peptides in the CRF- and AVP-producing cells in unstressed Japanese macaque monkeys (Macaca fuscata). Reverse transcription-polymerase chain reaction analysis showed the expression of both CRF and AVP mRNAs in the monkey PVH. As expected, in the magnocellular neurones of the PVH and supraoptic nucleus, essentially no CRF immunoreactivity could be detected in NPII-immunoreactive (AVP-producing) neurones. Immunofluorescence showed that, in the parvocellular part of the PVH, NPII was detectable in a subpopulation (approximately 39%) of the numerous CRF-immunoreactive neuronal perikarya, whereas, in the outer median eminence, NPII was more prominent (approximately 52%) in the CRF varicosities. Triple immunoelectron microscopy in the median eminence demonstrated the presence of both NPII and copeptin immunoreactivity in dense-cored vesicles of CRF-containing axons. The results are consistent with an idea that the AVP propeptide is processed and NPII and copeptin are colocalised in hypothalamic-pituitary CRF axons in the median eminence of a primate. The CRF, AVP and copeptin are all co-packaged in neurosecretory vesicles in monkeys and are thus likely to be co-released into the portal capillary blood to amplify ACTH release from the primate anterior pituitary.

    DOI: 10.1111/jne.12875

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  • Detection and Characterization of Estrogen Receptor Beta Expression in the Brain with Newly Developed Transgenic Mice. 国際誌

    Shoko Sagoshi, Sho Maejima, Masahiro Morishita, Satoshi Takenawa, Akito Otubo, Keiko Takanami, Tatsuya Sakamoto, Hirotaka Sakamoto, Shinji Tsukahara, Sonoko Ogawa

    Neuroscience   438   182 - 197   2020年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Two types of nuclear estrogen receptors, ERα and ERβ, have been shown to be differentially involved in the regulation of various types of behaviors. Due to a lack of tools for identifying ERβ expression, detailed anatomical distribution and neurochemical characteristics of ERβ expressing cells and cellular co-expression with ERα remain unclear. We have generated transgenic mice ERβ-RFPtg, in which RFP was inserted downstream of ERβ BAC promotor. We verified RFP signals as ERβ by confirming: (1) high ERβ mRNA levels in RFP-expressing cells collected by fluorescence-activated cell sorting; and (2) co-localization of ERβ mRNA and RFP proteins in the paraventricular nucleus (PVN). Strong ERβ-RFP signals were found in the PVN, medial preoptic area (MPOA), bed nucleus of the stria terminalis, medial amygdala (MeA), and dorsal raphe nucleus (DRN). In the MPOA and MeA, three types of cell populations were identified; those expressing both ERα and ERβ, and those expressing exclusively either ERα or ERβ. The majority of PVN and DRN cells expressed only ERβ-RFP. Further, ERβ-RFP positive cells co-expressed oxytocin in the PVN, and tryptophan hydroxylase 2 and progesterone receptors in the DRN. In the MeA, some ERβ-RFP positive cells co-expressed oxytocin receptors. These findings collectively suggest that ERβ-RFPtg mice can be a powerful tool for future studies on ERβ function in the estrogenic regulation of social behaviors.

    DOI: 10.1016/j.neuroscience.2020.04.047

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  • The phosphatidylcholine transfer protein StarD7 is important for myogenic differentiation in mouse myoblast C2C12 cells and human primary skeletal myoblasts. 国際誌

    Yasuhiro Horibata, Satomi Mitsuhashi, Hiroaki Shimizu, Sho Maejima, Hirotaka Sakamoto, Chieko Aoyama, Hiromi Ando, Hiroyuki Sugimoto

    Scientific reports   10 ( 1 )   2845 - 2845   2020年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    StarD7 is a phosphatidylcholine (PC)-specific lipid transfer protein essential for the maintenance of mitochondrial PC composition, morphogenesis, and respiration. Here, we studied the role of StarD7 in skeletal myoblast differentiation using mouse myoblast C2C12 cells and human primary myoblasts. Immunofluorescence and immuno-electron microscopy revealed that StarD7 was distributed in the cytosol, inner mitochondria space, and outer leaflet of the outer mitochondrial membrane in C2C12 cells. Unlike human kidney embryonic cell line HEK293 cells, the mitochondrial proteinase PARL was not involved in the processing and maturation of StarD7 in C2C12 cells. StarD7 was constantly expressed during myogenic differentiation of C2C12 cells. The siRNA-mediated knockdown of StarD7 in C2C12 cells and human primary myoblasts significantly impaired myogenic differentiation and reduced the expression of myomaker, myomerger and PGC-1α. The reduction in mitochondrial PC levels and oxygen consumption rates, decreased expression of myomaker, myomerger and PGC-1α, as well as impaired myogenic differentiation, were completely restored when the protein was reintroduced into StarD7-knockout C2C12 cells. These results suggest that StarD7 is important for skeletal myogenesis in mammals.

    DOI: 10.1038/s41598-020-59444-y

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  • VGF in the medial preoptic nucleus increases sexual activity following sexual arousal induction in male rats. 査読 国際誌

    Maejima S, Abe Y, Yamaguchi S, Musatov S, Ogawa S, Kondo Y, Tsukahara S

    Endocrinology   159 ( 12 )   3993 - 4005   2018年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1210/en.2018-00804

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  • Sexual experience reduces neuronal activity in the central part of the medial preoptic nucleus in male rats during sexual behavior. 査読 国際誌

    Yamaguchi S, Abe Y, Maejima S, Tsukahara S

    Neuroscience letters   685   155 - 159   2018年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.neulet.2018.08.037

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  • Sexual behavior-associated c-Fos induction in the sagittalis nucleus of the hypothalamus in male rat 査読 国際誌

    Ken Ichi Matsuda, Kei Uchiyama, Hiroko Mori, Sho Maejima, Shohei Yamaguchi, Masaki Tanaka, Shinji Tsukahara

    NEUROSCIENCE LETTERS   661   104 - 107   2017年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER IRELAND LTD  

    The sagittalis nucleus of the hypothalamus (SGN) is a small nucleus located in the interstitial area between the arcuate and ventromedial nuclei of the hypothalamus in rats. The SGN exhibits male-biased sexual dimorphism and expresses estrogen receptor a and calbindin-D28 K. This suggests a contribution of the SGN to sexually differentiated brain function, but its functional role is unknown. In this study, neuronal activation in the SGN during sexual behavior in male rats was examined by c-Fos immunohistochemistry. The number of c-Fos-immunoreactive (c-Fos-ir) cells was elevated with only exposure to chemosensory cues of estrous females and significantly increased after the first mount. The first intromission and ejaculation did not induce further increases in the number of c-Fos-ir cells in the SGN. These findings suggest that the SGN is involved in regulation of the early phase of male sexual behavior, including motivation.

    DOI: 10.1016/j.neulet.2017.09.053

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  • Gonadal Hormone-Dependent Sexual Differentiation of a Female-Biased Sexually Dimorphic Cell Group in the Principal Nucleus of the Bed Nucleus of the Stria Terminalis in Mice 査読 国際誌

    Masahiro Morishita, Sho Maejima, Shinji Tsukahara

    ENDOCRINOLOGY   158 ( 10 )   3512 - 3525   2017年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS INC  

    We recently reported a female-biased sexually dimorphic area in the mouse brain in the boundary region between the preoptic area and the bed nucleus of the stria terminalis (BNST). We reexamined this area and found that it is a ventral part of the principal nucleus of the BNST (BNSTp). The BNSTp is a male-biased sexually dimorphic nucleus, but the ventral part of the BNSTp (BNSTpv) exhibits female-biased sex differences in volume and neuron number. The volume and neuron number of the BNSTpv were increased in males by neonatal orchiectomy and decreased in females by treatment with testosterone, dihydrotestosterone, or estradiol within 5 days after birth. Sex differences in the volume and neuron number of the BNSTpv emerged before puberty. These sex differences became prominent in adulthood with increasing volume in females and loss of neurons in males during the pubertal/adolescent period. Prepubertal orchiectomy did not affect the BNSTpv, although prepubertal ovariectomy reduced the volume increase and induced loss of neurons in the female BNSTpv. In contrast, the volume and neuron number of male-biased sexually dimorphic nuclei that are composed of mainly calbindin neurons and are located in the preoptic area and BNST were decreased by prepubertal orchiectomy but not affected by prepubertal ovariectomy. Testicular testosterone during the postnatal period may defeminize the BNSTpv via binding directly to the androgen receptor and indirectly to the estrogen receptor after aromatization, although defeminization may proceed independently of testicular hormones in the pubertal/adolescent period. Ovarian hormones may act to feminize the BNSTpv during the pubertal/adolescent period. A male-biased sexually dimorphic nucleus contains a cell group showing female-biased sex differences. This cell group is sexually differentiated by perinatal and pubertal gonadal hormones.

    DOI: 10.1210/en.2017-00240

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  • Arsenic Exposure Induces Unscheduled Mitotic S Phase Entry Coupled with Cell Death in Mouse Cortical Astrocytes 査読 国際誌

    Nang T. T. Htike, Fumihiko Maekawa, Haruka Soutome, Kazuhiro Sano, Sho Maejima, Kyaw H. Aung, Masaaki Tokuda, Shinji Tsukahara

    FRONTIERS IN NEUROSCIENCE   10   297 - 297   2016年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:FRONTIERS MEDIA SA  

    There is serious concern about arsenic in the natural environment, which exhibits neurotoxicity and increases the risk of neurodevelopmental disorders. Adverse effects of arsenic have been demonstrated in neurons, but it is not fully understood how arsenic affects other cell types in the brain. In the current study, we examined whether sodium arsenite (NaAsO2) affects the cell cycle, viability, and apoptosis of in vitro-cultured astrocytes isolated from the cerebral cortex of mice. Cultured astrocytes from transgenic mice expressing fluorescent ubiquitination-based cell cycle indicator (Fucci) were subjected to live imaging analysis to assess the effects of NaAsO2 (0, 1, 2, and 4 mu M) on the cell cycle and number of cells. Fucci was designed to express monomeric Kusabira Orange2 (mKO(2)) fused with the ubiquitylation domain of hCdt1, a marker of G1 phase, and monomeric Azami Green (mAG) fused with the ubiquitylation domain of hGem, a marker of S, G2, and M phases. NaAsO2 concentration-dependently decreased the peak levels of the mAG/mKO2 emission ratio when the ratio had reached a peak in astrocytes without NaAsO2 exposure, which was due to attenuating the increase in the mAG-expressing cell number. In contrast, the mAG/mKO(2) emission ratio and number of mAG-expressing cells were concentration-dependently increased by NaAsO2 before their peak levels, indicating unscheduled S phase entry. We further examined the fate of cells forced to enter S phase by NaAsO2. We found that most of these cells died up to the end of live imaging. In addition, quantification of the copy number of the glial fibrillary acidic protein gene expressed specifically in astrocytes revealed a concentration dependent decrease caused by NaAsO2. However, NaAsO2 did not increase the amount of nucleosomes generated from DNA fragmentation and failed to alter the gene expression of molecules relevant to unscheduled S phase entry-coupled apoptosis (p21, p53, E2F1, E2F4, and Gm36566). These findings suggest that NaAsO2 adversely affects the cell cycle and viability of astrocytes by inducing unscheduled S phase entry coupled with cell death that may be caused by mechanisms other than apoptosis.

    DOI: 10.3389/fnins.2016.00297

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  • A neural connection between the central part of the medial preoptic nucleus and the bed nucleus of the stria terminalis to regulate sexual behavior in male rats 査読 国際誌

    Sho Maejima, Naoya Ohishi, Shohei Yamaguchi, Shinji Tsukahara

    NEUROSCIENCE LETTERS   606   66 - 71   2015年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER IRELAND LTD  

    The medial preoptic nucleus (MPN) is a regulatory center for male sexual behavior. It consists of sexually dimorphic structures that are male biased, and these structures are found in the central part of the MPN (MPNc). The bed nucleus of the stria terminalis (BNST) also participates in male sexual behavior, and receives efferent neural projections from the MPNc. In this study, we examined if MPNc neurons projecting to the BNST are activated in male rats displaying sexual behavior. Fluoro-Gold (FG; a retrograde neural tracer) was injected into the BNST of male rats, which were separated into two groups: (1) those in contact with estrus female rats and displayed sexual behavior followed by ejaculation and (2) those without contact with estrous female rats. In both groups, protein expression of c-Fos (a neuronal activity marker) and calbindin (a location marker of the MPNc) were detected by fluorescent immunohistochemistry. The number of c-Fos-immunoreactive cells with or without FG labeling in the MPNc was also measured. The number of c-Fos-immunoreactive cells significantly increased following ejaculation. Approximately 10% of FG-labeled cells in ejaculation male rats were immunoreactive for c-Fos, and this percentage value was significantly higher in this group compared with control male rats. Overall, these results suggest that efferent projections from the MPNc to the BNST function to control sexual behavior in male rats. (C) 2015 Elsevier Ireland Ltd. All rights reserved.

    DOI: 10.1016/j.neulet.2015.08.047

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  • Characterization of an avian histidine decarboxylase and localization of histaminergic neurons in the chicken brain 査読 国際誌

    Yuki Bessho, Eiko Iwakoshi-Ukena, Tetsuya Tachibana, Sho Maejima, Shusuke Taniuchi, Keiko Masuda, Kenshiro Shikano, Kunihiro Kondo, Megumi Furumitsu, Kazuyoshi Ukena

    NEUROSCIENCE LETTERS   578   106 - 110   2014年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER IRELAND LTD  

    In mammals, it is established that histamine is a neurotransmitter and/or neuromodulator in the central nervous system. It is produced by the enzyme histidine decarboxylase (HDC) in the tuberomammillary nucleus of the posterior hypothalamus. However, HDC as well as histaminergic neurons have not yet been characterized in the avian brain. We have cloned the cDNA for HDC from the chicken hypothalamus and demonstrated that the chicken HDC sequence is highly homologous to the mammalian counterpart, and that the expressed protein shows high enzymatic activity. The expression of HDC mRNA at various sites in the brain was investigated using quantitative RT-PCR. The results showed that the HDC mRNA was highly expressed in the hypothalamic infundibulum. In situ hybridization analyses revealed that the cells containing HDC mRNA were localized in the medial mammillary nucleus of the hypothalamic infundibulum. Intracerebroventricular injection of histamine in chicks resulted in inhibition of feeding behavior. This is the first report of the characterization of histaminergic neurons in the avian brain, and our findings indicate that neuronal histamine exerts anorexigenic effects in chicks. (C) 2014 Elsevier Ireland Ltd. All rights reserved.

    DOI: 10.1016/j.neulet.2014.06.048

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  • Identification of Neurotensin and LANT-6 and Localization of mRNA Encoding Their Precursor in the Chicken Brain 査読

    Keiko Masuda, Eiko Iwakoshi-Ukena, Yuki Bessho, Shusuke Taniuchi, Sho Maejima, Kenshiro Shikano, Kunihiro Kondo, Megumi Furumitsu, Kazuyoshi Ukena

    ZOOLOGICAL SCIENCE   31 ( 6 )   353 - 359   2014年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ZOOLOGICAL SOC JAPAN  

    Neurotensin (NT) and neurotensin-related peptide (Lys(8), Asn(9), NT8-13: LANT-6) have previously been purified from chicken intestine. However, the presence of these peptides and the localization of their precursor mRNA in the brain were not well understood. In the present study, through a comprehensive analysis of bioactive substances, NT and LANT-6 were identified in the chicken brain using tandem mass spectrometry combined with a bioassay of the colon contraction. The effect of NT and LANT-6 on the colon contraction was assessed, and NT was found to be 10 times more potent than LANT-6. Furthermore, the sites of NT/LANT-6 precursor mRNA expression in the brain were investigated using quantitative RT-PCR. The result showed that the mRNA was expressed most in the telencephalon, followed by the diencephalon. In situ hybridization analysis revealed that cells containing NT/LANT-6 precursor mRNA were widely distributed throughout the brain except for the cerebellum. Additionally, these were highly concentrated in the frontal telencephalon, including the nidopallium, hyperpallium, and hippocampus. Collectively, these results indicate that NT and LANT-6 are produced in the chicken brain, and they may participate in multiple functions.

    DOI: 10.2108/zs140010

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  • Identification of a cDNA encoding a novel small secretory protein, neurosecretory protein GL, in the chicken hypothalamic infundibulum 査読 国際誌

    Kazuyoshi Ukena, Eiko Iwakoshi-Ukena, Shusuke Taniuchi, Yuki Bessho, Sho Maejima, Keiko Masuda, Kenshiro Shikano, Kunihiro Kondo, Megumi Furumitsu, Tetsuya Tachibana

    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS   446 ( 1 )   298 - 303   2014年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    To find novel neuropeptide and/or peptide hormone precursors in the avian brain, we performed a cDNA subtractive screen of the chicken hypothalamic infundibulum, which contains one of the feeding and neuroendocrine centers. After sequencing 596 clones, we identified a novel cDNA encoding a previously unknown protein. The deduced precursor protein consisted of 182 amino acid residues, including one putative small secretory protein of 80 amino acid residues. This small protein was flanked at the N-terminus by a signal peptide and at the C-terminus by a glycine amidation signal and a dibasic amino acid cleavage site. Because the predicted C-terminal amino acids of the small protein were Gly-Leu-NH2, the small protein was named neurosecretory protein GL (NPGL). Quantitative RT-PCR analysis demonstrated specific expression of the NPGL precursor mRNA in the hypothalamic infundibulum. Furthermore, the mRNA levels in the hypothalamic infundibulum increased during post-hatching development. In situ hybridization analysis showed that the cells containing the NPGL precursor mRNA were localized in the medial mammillary nucleus and infundibular nucleus within the hypothalamic infundibulum of 8- and 15-day-old chicks. Subcutaneous infusion of NPGL in chicks increased body weight gain without affecting food intake. To our knowledge, this is the first report to describe the identification and localization of the NPGL precursor mRNA and the function of its translated product in animals. Our findings indicate that NPGL may participate in the growth process in chicks. (c) 2014 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.bbrc.2014.02.090

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  • Changes in plasma angiotensin II, aldosterone, arginine vasotocin, corticosterone, and electrolyte concentrations during acclimation to dry condition and seawater in the crab-eating frog 査読 国際誌

    Minoru Uchiyama, Sho Maejima, Marty K. S. Wong, Narin Preyavichyapugdee, Chaitip Wanichanon, Susumu Hyodo, Yoshio Takei, Kouhei Matuda

    GENERAL AND COMPARATIVE ENDOCRINOLOGY   195   40 - 46   2014年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    The crab-eating frog Fejervarya cancrivora inhabits mangrove swamps and marshes in Southeast Asia. In the present study, circulating angiotensin II (Ang II), aldosterone (Aldo), arginine vasotocin (AVT), and corticosterone (Cort) concentrations as well as various blood parameters were studied under osmotically stressful conditions. Following acclimation to hyperosmotic seawater and dry condition for 5 days, body weight was significantly decreased. Under both conditions, plasma Na, Cl, and urea concentrations, hematocrit values (Ht; blood volume indicator), and osmolality were significantly increased. Dehydration associated with hypovolemic and hyperosmotic states of body fluids was induced during acclimation to hyperosmotic seawater and dry condition in the crab-eating frogs. Ang II, Aldo, AVT, and Cort were maintained within relatively narrow concentration ranges in the control frogs; however, in frogs under dry and hyperosmotic seawater conditions, large variations were observed among individuals in each group. Mean plasma Ang II and Aldo concentrations significantly increased in hyperosmotic seawater-acclimated and desiccated frogs. Although mean plasma AVT concentrations in dehydrated frogs of both the groups were approximately 2.0-3.5 times higher than those in the control frogs, the differences were not significant because of the variation. There was a significant correlation between plasma osmolality and AVT as well as Ang II but not Aldo. A significant correlation was also observed between Ht and AVT as well as Ang II. Plasma Ang II was significantly correlated with plasma Aldo. These results indicate that the crab-eating frogs may exhibit similar physiological responses to both seawater-acclimated and dry conditions. It appears that under dehydrated conditions, osmoregulatory mechanisms participate in stabilization of the situation. The renin-angiotensin system may have pivotal roles in body fluid regulation under volemic and osmotic stress in the Fejervalya species with unique osmoregulation. (C) 2013 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.ygcen.2013.10.013

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  • The epithelial sodium channel in the Australian lungfish, Neoceratodus forsteri (Osteichthyes: Dipnoi) 査読 国際誌

    Minoru Uchiyama, Sho Maejima, Sumio Yoshie, Yoshihiro Kubo, Norifumi Konno, Jean M. P. Joss

    PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES   279 ( 1748 )   4795 - 4802   2012年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC  

    Epithelial sodium channel (ENaC) is a Na+-selective, aldosterone-stimulated ion channel involved in sodium transport homeostasis. ENaC is rate-limiting for Na+ absorption in the epithelia of osmoregulatory organs of tetrapods. Although the ENaC/degenerin gene family is proposed to be present in metazoans, no orthologues or paralogues for ENaC have been found in the genome databases of teleosts. We studied full-length cDNA cloning and tissue distributions of ENaC alpha, beta and gamma subunits in the Australian lungfish, Neoceratodus forsteri, which is the closest living relative of tetrapods. Neoceratodus ENaC (nENaC) comprised three subunits: nENaC alpha, beta and gamma proteins. The nENaC alpha, beta and gamma subunits are closely related to amphibian ENaC alpha, beta and gamma subunits, respectively. Three ENaC subunit mRNAs were highly expressed in the gills, kidney and rectum. Amiloride-sensitive sodium current was recorded from Xenopus oocytes injected with the nENaC alpha beta gamma subunit complementary RNAs under a two-electrode voltage clamp. nENaC alpha immunoreactivity was observed in the apical cell membrane of the gills, kidney and rectum. Thus, nENaC may play a role in regulating sodium transport of the lungfish, which has a renin-angiotensin-aldosterone system. This is interesting because there may have been an ENaC sodium absorption system controlled by aldosterone before the conquest of land by vertebrates.

    DOI: 10.1098/rspb.2012.1945

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  • Stimulatory effect of intracerebroventricular administration of orexin A on food intake in the zebrafish, Danio rerio 査読 国際誌

    Eri Yokobori, Kenji Kojima, Morio Azuma, Ki Sung Kang, Sho Maejima, Minoru Uchiyama, Kouhei Matsuda

    PEPTIDES   32 ( 7 )   1357 - 1362   2011年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE INC  

    Orexin is a potent orexigenic neuropeptide implicated in feeding regulation of mammals. However, except for the case of goldfish, the involvement of orexin in the feeding behavior of teleost fish has not well been studied. Therefore, we investigated the role of orexin on food intake using a zebrafish (Danio redo) model. We examined the effect of feeding status on orexin-like immunoreactivity and the expression level of orexin transcript in the brain. The number of neuronal cells showing orexin-like immunoreactivity in the hypothalamic region, including the posterior tuberal nucleus, was significantly increased in fish fasted for 7 days. Orexin precursor mRNA levels in the brain obtained from fish fasted for 7 days were higher than those in fish that had been fed normally. We then investigated the effect of intracerebroventricular (ICV) administration of orexin A on food intake. Cumulative food intake was significantly increased by ICV administration of orexin A (at 0.3 and 3 pmol/g body weight, BW) during a 60-min observation period after treatment. The orexin A-induced orexigenic action (at 0.3 pmol/g BW) was blocked by treatment with an orexin receptor antagonist, SB334867, at 10 pmol/g BW. These results indicate that orexin A acts as feeding regulator in the zebrafish. (C) 2011 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.peptides.2011.05.010

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  • Central angiotensin II stimulates cutaneous water intake behavior via an angiotensin II type-1 receptor pathway in the Japanese tree frog Hyla japonica 査読 国際誌

    Sho Maejima, Norifumi Konno, Kouhei Matsuda, Minoru Uchiyama

    HORMONES AND BEHAVIOR   58 ( 3 )   457 - 464   2010年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    Angiotensin II (Ang II) stimulates oral water intake by causing thirst in all terrestrial vertebrates except anurans. Anuran amphibians do not drink orally but absorb water osmotically through ventral skin. In this study, we examined the role of Ang II on the regulation of water-absorption behavior in the Japanese tree frog (Hyla japonica). In fully hydrated frogs, intracerebroventricular (ICV) and intralymphatic sac (ILS) injection of Ang II significantly extended the residence time of water in a dose-dependent manner. Ang II-dependent water uptake was inhibited by ICV pretreatment with an angiotensin II type-1 (AT(1)) receptor antagonist but not a type-2 (AT(2)) receptor antagonist. These results suggest that Ang II stimulates water-absorption behavior in the tree frog via an AT(1)-like but not AT(2)-like receptor. We then cloned and characterized cDNA of the tree frog AT(1) receptor from the brain. The tree frog AT(1) receptor cDNA encodes a 361 amino acid residue protein, which is 87% identical to the toad (Bufo marinus) AT(1) receptor and exhibits the functional characteristics of an Ang II receptor. AT(1) receptor mRNAs were found to be present in a number of tissues including brain (especially in the diencephalon), lung, large intestine, kidney and ventral pelvic skin. When tree frogs were exposed to dehydrating conditions, AT(1) receptor mRNA significantly increased in the diencephalon and the rhombencephalon. These data suggest that central Ang II may control water intake behavior via an AT(1) receptor on the diencephalon and rhombencephalon in anuran amphibians and may have implications for water consumption in vertebrates. (C) 2010 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.yhbeh.2010.05.007

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  • Effects of hypertonic stimuli and arginine vasotocin (AVT) on water absorption response in Japanese treefrog, Hyla japonica 査読 国際誌

    Sho Maejima, Toshiki Yamada, Takayuki Hamada, Kouhei Matsuda, Minoru Uchiyama

    GENERAL AND COMPARATIVE ENDOCRINOLOGY   157 ( 2 )   196 - 202   2008年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    Anuran amphibians do not drink orally but absorb water osmotically through the highly permeable ventral skin. In this cutaneous water absorption, roles of the putative cerebral osmoreceptors and functions of arginine vasotocin (AVT) were examined in the central nervous system of the Japanese treefrog, Hyla japonica. Intracerebroventricular (ICV) or intralymphatic sac (ILS) administration of various hypertonic solutions (NaCl, mannitol and urea) significantly extended the residence time in water in a dose-dependent manner, suggesting facilitation of water absorption in frogs. ICV injection of AVT also increased significantly the residence time in a dose-dependent manner. The water absorption effect of AVT was significantly inhibited by pretreatment of ICV OPC-21268, a vasopressin V, receptor antagonist. But pre-ICV injection of OPC-31260, a vasopressin V-2 receptor antagonist, did not block the water absorption effect of AVT. Extension of the residence time induced by hyperosmotic NaCl (1000 mOsm) ICV injection was significantly inhibited by pretreatment of ICV OPC-21268. The present results showed that increases of osmotic pressure in plasma and/or cerebrospinal fluid stimulate water absorption response, suggesting that osmoreceptors are certainly present in the central nervous system and AVT may directly stimulate water absorption in the treefrog. It is also suggested that AVT activates cellular mechanisms via VI-like but not V-2-like receptors in the central nervous system and facilitates water absorption response in the treefrog. (c) 2008 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.ygcen.2008.04.014

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