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Neurohypophysial Hormones Regulate Amphibious Behaviour in the Mudskipper Goby

Tatsuya Sakamoto, Yudai Nishiyama, Aoi Ikeda, Hideya Takahashi, Susumu Hyodo, Nao Kagawa, Hirotaka Sakamoto

PLOS ONE 10 ( 7 ) 2015年7月

記述言語：英語出版者・発行元：PUBLIC LIBRARY SCIENCE

The neurohypophysial hormones, arginine vasotocin and isotocin, regulate both hydromineral balance and social behaviors in fish. In the amphibious mudskipper, Periophthalmus modestus, we previously found arginine-vasotocin-specific regulation of aggressive behavior, including migration of the submissive subordinate into water. This migration also implies the need for adaptation to dehydration. Here, we examined the effects of arginine vasotocin and isotocin administration on the amphibious behavior of individual mudskippers in vivo. The mudskippers remained in the water for an increased period of time after 1-8 h of intracerebroventricular (ICV) injection with 500 pg/g arginine vasotocin or isotocin. The 'frequency of migration' was decreased after ICV injection of arginine vasotocin or isotocin, reflecting a tendency to remain in the water. ICV injections of isotocin receptor antagonist with arginine vasotocin or isotocin inhibited all of these hormonal effects. In animals kept out of water, mRNA expression of brain arginine vasotocin and isotocin precursors increased 3- and 1.5-fold, respectively. Given the relatively wide distribution of arginine vasotocin fibres throughout the mudskipper brain, induction of arginine vasotocin and isotocin under terrestrial conditions may be involved also in the preference for an aquatic habitat as ligands for brain isotocin receptors.

DOI： 10.1371/journal.pone.0134605

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Invivo processing and release into the circulation of GFP fusion protein in arginine vasopressin enhanced GFP transgenic rats: response to osmotic stimulation

Keita Satoh, Takumi Oti, Akiko Katoh, Yoichi Ueta, John F. Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

FEBS JOURNAL 282 ( 13 ) 2488 - 2499 2015年7月

記述言語：英語出版者・発行元：WILEY-BLACKWELL

Arginine vasopressin (AVP) is a neurohypophysial hormone synthesized as a part of a prepropeptide precursor containing the signal peptide, AVP hormone, AVP-associated neurophysin II and copeptin in the hypothalamic neurosecretory neurons. A transgenic (Tg) rat line expressing the AVP-eGFP fusion gene has been generated. To establish the AVP-eGFP Tg rat as a unique model for an analysis of AVP dynamics invivo, we first examined the invivo molecular dynamics of the AVP-eGFP fusion gene, and then the release of GFP in response to physiological stimuli. Double immunoelectron microscopy demonstrated that GFP was specifically localized in neurosecretory vesicles of AVP neurons in this Tg rat. After stimulation of the posterior pituitary with high potassium we demonstrated the exocytosis of AVP neurosecretory vesicles containing GFP at the ultrastructural level. Biochemical analyses indicated that the AVP-eGFP fusion gene is subjected to invivo post-translational modifications like the native AVP gene, and is packaged into neurosecretory vesicles as a fusion protein: copeptin(1-14)-GFP. Moreover, GFP release into the circulating blood appeared to be augmented after osmotic stimulation, like native AVP. Thus, here we show for the first time the invivo molecular processing of the AVP-eGFP fusion gene and stimulated secretion after osmotic stimulation in rats. Because GFP behaved like native AVP in the hypothalamo-pituitary axis, and in particular was released into the circulation in response to a physiological stimulus, the AVP-eGFP Tg rat model appears to be a powerful tool for analyzing neuroendocrine systems at the organismal level.

DOI： 10.1111/febs.13291

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Effective synaptome analysis of itch-mediating neurons in the spinal cord: A novel immunohistochemical methodology using high-voltage electron microscopy

Keita Satoh, Keiko Takanami, Kazuyoshi Murata, Mitsuhiro Kawata, Tatsuya Sakamoto, Hirotaka Sakamoto

NEUROSCIENCE LETTERS 599 86 - 91 2015年7月

記述言語：英語出版者・発行元：ELSEVIER IRELAND LTD

Transmission electron microscopy (TEM) is used for three-dimensional (3-D) analysis of synaptic connections in neuroscience research. However, 3-D reconstruction of the synapses using serial ultrathin sections is a powerful but tedious approach requiring advanced technical skills. High-voltage electron microscopy (HVEM) allows examination of thicker sections of biological specimens due to the increased penetration of the more accelerated electrons, which is useful to analyze the 3-D structure of biological specimens. However, it is still difficult to visualize the neural networks and synaptic connections in 3-D using HVEM because of insufficient and non uniform heavy metal staining in the membranous structures in semi-thin sections. Here, we present the successful chemical 3-D neuroanatomy of the rat spinal dorsal horn at the ultrastructural level as a first step for effective synaptome analysis by applying a high-contrast en bloc staining method to immune-HVEM tomography. Our new approach made it possible to examine many itch-mediating synaptic connections and neural networks in the spinal cord simultaneously using HVEM tomography. This novel 3-D electron microscopy is very useful for the analysis of synaptic structure and the chemical neuroanatomy at the 3-D ultrastructural level. (C) 2015 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.neulet.2015.05.031

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Requirement of vasotocin for being a winner in love triangle relationships (two males and one female) of medaka fish

Yokoi S, Sakamoto, T

AQUABIOLOGY 37(6) 591-597 2015 2015年

07B01 瀬戸内海を題材とした小学校理科第6学年「生き物のくらしと環境」の授業開発 : Place-Based Educationの観点を参考にして(環境教育,一般研究発表(口頭発表))

土屋美和, 定金なつみ, 藤井浩樹, 田中喜一郎, 筒井直昭, 小林靖尚, 坂本竜哉

日本理科教育学会全国大会要項 ( 65 ) 199 - 199 2015年

Basic reproductive biology of daggertooth pike conger, Muraenesox cinereus: A possible model for oogenesis in Anguilliformes

Kobayashi, Y, T. Mototani

Zoological Letters 1(1): 1-7 (2015) 2015年

Hormonal Regulation of Body Fluid in Teleost Fishes

SAKAMOTO, T

Bulletin of the Society of Sea Water Science, Japan 69(4): 244-246 (2015) 69 ( 4 ) 244 - 246 2015年

外来種アメリカザリガニの駆除に用いる人工巣穴サイズ

牛見悠奈, 宮武優太, 筒井直昭, 坂本竜哉, 中田和義

応用生態工学 18 ( 2 ) 79 - 86 2015年

記述言語：日本語出版者・発行元：応用生態工学会

北米産外来種のアメリカザリガニは，在来生物の捕食などを通じて，在来生態系に深刻な影響を及ぼしている。また，本種が掘る巣穴が水田漏水の原因になるなど水田管理上の問題も引き起こしている。このため，本種は緊急対策外来種と日本の侵略的外来種ワースト 100 に指定され，効率的な駆除手法の開発が求められている。そこで本研究では，水田水域や河川・湖沼等に定着したアメリカザリガニの駆除に用いる人工巣穴の適したサイズを明らかにすることを目的として，本種による人工巣穴サイズ選好性実験を実施した。灰色の直管型の塩ビ管を人工巣穴とし，内径と長さの異なる人工巣穴をアメリカザリガニに室内水槽内で選択させた。その結果，人工巣穴の内径については，全長（X, mm）と好んで選択された内径（Y, mm）の間に Y＝0.58X＋4.26 という有意な回帰式が得られた。人工巣穴の長さについては，全長の 4 倍の長さの巣穴が好んで選択された。以上の結果をもとに，アメリカザリガニの駆除に用いる体サイズ別の人工巣穴サイズを提案した。

DOI： 10.3825/ece.18.79

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Effect of environmental salinity on expression of adrenomedullin genes suggests osmoregulatory activity in the medaka, Oryzias latipes.

Ogoshi, M, K. Kato

Zoological Letters 1(1): 1-7 (2015) 2015年

P4-12 AVP-eGFP TgラットにおけるインビボGFP動態(細胞生物・電子顕微鏡,ポスター発表,組織化学のモーダルシフト,第56回日本組織細胞化学会総会・学術集会)

佐藤慧太, 越智拓海, 加藤明子, 上田陽一, Morris John F, 坂本竜哉, 坂本浩隆

日本組織細胞化学会総会プログラムおよび抄録集 ( 56 ) 72 - 72 2015年

P8-03 霊長類ニホンザルの脊髄におけるgastrin-releasing peptide系の存在(脳機能,ポスター発表,組織化学のモーダルシフト,第56回日本組織細胞化学会総会・学術集会)

伊藤隆志, 高浪景子, 越智拓海, 小林靖尚, 佐藤慧太, 高橋俊次, 上田康雅, 坂本竜哉, 坂本浩隆

日本組織細胞化学会総会プログラムおよび抄録集 ( 56 ) 78 - 78 2015年

卵黄形成抑制ホルモンの作用機序解明に向けたクルマエビ卵巣の遺伝子の網羅的解析

筒井直昭, 小林靖尚, 泉川晃一, 坂本竜哉

日本水産学会大会講演要旨集 2014 100 2014年9月

Distribution of Gastrin-Releasing Peptide in the Rat Trigeminal and Spinal Somatosensory Systems

Keiko Takanami, Hirotaka Sakamoto, Ken Ichi Matsuda, Keita Satoh, Takashi Tanida, Shunji Yamada, Kaihei Inoue, Takumi Oti, Tatsuya Sakamoto, Mitsuhiro Kawata

JOURNAL OF COMPARATIVE NEUROLOGY 522 ( 8 ) 1858 - 1873 2014年6月

記述言語：英語出版者・発行元：WILEY-BLACKWELL

Gastrin-releasing peptide (GRP) has recently been identified as an itch-specific neuropeptide in the spinal sensory system in mice, but there are no reports of the expression and distribution of GRP in the trigeminal sensory system in mammals. We characterized and compared GRP-immunoreactive (ir) neurons in the trigeminal ganglion (TG) with those in the rat spinal dorsal root ganglion (DRG). GRP immunoreactivity was expressed in 12% of TG and 6% of DRG neurons and was restricted to the small- and medium-sized type cells. In both the TG and DRG, many GRP-ir neurons also expressed substance P and calcitonin gene-related peptide, but not isolectin B-4. The different proportions of GRP and transient receptor potential vanilloid 1 double-positive neurons in the TG and DRG imply that itch sensations via the TG and DRG pathways are transmitted through distinct mechanisms. The distribution of the axon terminals of GRP-ir primary afferents and their synaptic connectivity with the rat trigeminal sensory nuclei and spinal dorsal horn were investigated by using light and electron microscopic histochemistry. Although GRP-ir fibers were rarely observed in the trigeminal sensory nucleus principalis, oralis, and interpolaris, they were predominant in the superficial layers of the trigeminal sensory nucleus caudalis (Vc), similar to the spinal dorsal horn. Ultrastructural analysis revealed that GRP-ir terminals contained clear microvesicles and large dense-cored vesicles, and formed asymmetric synaptic contacts with a few dendrites in the Vc and spinal dorsal horn. These results suggest that GRP-dependent orofacial and spinal pruriceptive inputs are processed mainly in the superficial laminae of the Vc and spinal dorsal horn. J. Comp. Neurol. 522:1858-1873, 2014. (c) 2013 Wiley Periodicals, Inc.

DOI： 10.1002/cne.23506

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Effects of Inorganic Mercury and Methylmercury on Osteoclasts and Osteoblasts in the Scales of the Marine Teleost as a Model System of Bone

Koji Yachiguchi, Toshio Sekiguchi, Masaki Nakano, Atsuhiko Hattori, Megumi Yamamoto, Kei-ichiro Kitamura, Masahiro Maeda, Yoshiaki Tabuchi, Takashi Kondo, Hiromitsu Kamauchi, Hajime Nakabayashi, Ajai K. Srivastav, Kazuichi Hayakawa, Tatsuya Sakamoto, Nobuo Suzuki

ZOOLOGICAL SCIENCE 31 ( 5 ) 330 - 337 2014年5月

記述言語：英語出版者・発行元：ZOOLOGICAL SOC JAPAN

To evaluate the effects of inorganic mercury (InHg) and methylmercury (MeHg) on bone metabolism in a marine teleost, the activity of tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP) as indicators of such activity in osteoclasts and osteoblasts, respectively, were examined in scales of nibbler fish (Girella punctata). We found several lines of scales with nearly the same TRAP and ALP activity levels. Using these scales, we evaluated the influence of InHg and MeHg. TRAP activity in the scales treated with InHg (10(-5) and 10(-4) M) and MeHg (10(-6) to 10(-4) M) during 6 hrs of incubation decreased significantly. In contrast, ALP activity decreased after exposure to InHg (10(-5) and 10(-4) M) and MeHg (10(-)6 to 10(-4) M) for 18 and 36 hrs, although its activity did not change after 6 hrs of incubation. As in enzyme activity 6 hrs after incubation, mRNA expression of TRAP (osteoclastic marker) decreased significantly with InHg and MeHg treatment, while that of collagen (osteoblastic marker) did not change significantly. At 6 hrs after incubation, the mRNA expression of metallothionein, which is a metal-binding protein in osteoblasts, was significantly increased following treatment with InHg or MeHg, suggesting that it may be involved in the protection of osteoblasts against mercury exposure up to 6 hrs after incubation. To our knowledge, this is the first report of the effects of mercury on osteoclasts and osteoblasts using marine teleost scale as a model system of bone.

DOI： 10.2108/zs130265

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軟骨魚類アカエイの子宮内液に含まれるタンパク質の精製と解析

筒井直昭, 小林靖尚, 坂本竜哉

日本水産学会大会講演要旨集 2014 171 2014年3月

Androgen regulates development of the sexually dimorphic gastrin-releasing peptide neuron system in the lumbar spinal cord: Evidence from a mouse line lacking androgen receptor in the nervous system

Hirotaka Sakamoto, Kazuhiro Saito, Clarisse Marie-Luce, Kalina Raskin, Takumi Oti, Keita Satoh, Kei Tamura, Tatsuya Sakamoto, Sakina Mhaouty-Kodja

NEUROSCIENCE LETTERS 558 109 - 114 2014年1月

記述言語：英語出版者・発行元：ELSEVIER IRELAND LTD

Androgens including testosterone, organize the nervous system as well as masculine external and internal genitalia during the perinatal period. Androgen organization involves promotion of masculine body features, usually by acting through androgen receptors (ARs). We have recently demonstrated that the gastrin-releasing peptide (GRP) system in the lumbar spinal cord also mediates spinal centers promoting penile reflexes during male sexual behavior in rats. Testosterone may induce sexual differentiation of this spinal GRP system during development and maintain its activation in adulthood. In the present study, we examined the role of ARs in the nervous system regulating the development of the sexually dimorphic GRP system. For this purpose, we used a conditional mouse line selectively lacking the AR gene in the nervous system. AR foxed males carrying (mutants) or not (controls) the nestin-Cre transgene were castrated in adulthood and supplemented with physiological amounts of testosterone. Loss of AR expression in the nervous system resulted in a significant decrease in the number of GRP neurons compared to control littermates. Consequently, the intensity of GRP axonal projections onto the lower lumbar and upper sacral spinal cord was greater in control males than in mutant males. These results suggest that ARs expressed in the nervous system play a significant role in the development of the GRP system in the male lumbar spinal cord. The AR-deletion mutation may attenuate sexual behavior and activity of mutant males via spinal GRP system-mediated neural mechanisms. (C) 2013 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.neulet.2013.10.068

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Functions of two distinct "prolactin-releasing peptides" evolved from a common ancestral gene

Tetsuya Tachibana, Tatsuya Sakamoto

FRONTIERS IN ENDOCRINOLOGY 5 2014年

記述言語：英語掲載種別：書評論文，書評，文献紹介等出版者・発行元：FRONTIERS MEDIA SA

Prolactin-releasing peptide (PrRP) is one of the RF-amide peptides and was originally identified in the bovine hypothalamus as a stimulator of prolactin (PRL) release. Independently, another RF-amide peptide was found in Japanese crucian carp and named Carassius-RFa (C-RFa), which shows high homology to PrRP and stimulates PRL secretion in teleost fish. Therefore, C-RFa has been recognized as fish PrRP. However, recent work has revealed that PrRP and C-RFa in non-mammalian vertebrates are encoded by separate genes originated through duplication of an ancestral gene. Indeed, both PrRP and C-RFa are suggested to exist in teleost, amphibian, reptile, and avian species. Therefore, we propose that non-mammalian PrRP (C-RFa) be renamed PrRP2. Despite a common evolutionary origin, PrRP2 appears to be a physiological regulator of PRL, whereas this is not a consistent role for PrRP itself. Further work revealed that the biological functions of PrRP and PrRP2 are not limited solely to PRL release, because they are also neuro-modulators of several hypothalamus pituitary axes and are involved in some brain circuits related to the regulation of food intake, stress, and cardiovascular functions. However, these actions appear to be different among vertebrates. For example, central injection of PrRP inhibits feeding behavior in rodents and teleosts, while it stimulates it in chicks. Therefore, both PrRP and PrRP2 have acquired diverse actions through evolution. In this review, we integrate the burgeoning information of structures, expression profiles, and multiple biological actions of PrRP in higher vertebrates, as well as those of PrRP2 in non-mammals.

DOI： 10.3389/fendo.2014.00170

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Diverse hormonal control of osmoregulation in euryhaline teleosts

Y. Takei, H. Takahashi, J. Hiroi, T. Sakamoto

Am J Physiol Regul Integr Comp Physiol. 307 (2014) 778-792 2014年

Effects of fasting and refeeding on intestinal cell proliferation and apoptosis in hammerhead shark (Sphyrna lewini).

H. Takahashi, S. Hyodo, T. Abe, C. Takagi, E.G. Grau, T. Sakamoto

J Coast Life Med. 2 (2014) 253-258 2014年

Marine macrophyte (eelgrass, Zostera marina) bed creation base research for conservation (2) The function of coleoptile in the seed germination of the eelgrass: Factor recognising bottom mud surface.

T. Fukuda, Y. Kohda, T. Sakamoto

J Kibi Int Univ Res Inst Health Welfare. 15 (2014) 13-19. 2014年

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