Faculty Profiles - SAKAMOTO Hirotaka

MISC - SAKAMOTO Hirotaka

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Quality Control of Photosystem II: Direct Imaging of the Changes in the Thylakoid Structure and Distribution of FtsH Proteases in Spinach Chloroplasts under Light Stress

Miho Yoshioka-Nishimura, Daisuke Nanba, Takashi Takaki, Chikako Ohba, Nodoka Tsumura, Noriko Morita, Hirotaka Sakamoto, Kazuyoshi Murata, Yasusi Yamamoto

PLANT AND CELL PHYSIOLOGY 55 ( 7 ) 1255 - 1265 2014.7

Language：English Publisher：OXFORD UNIV PRESS

Under light stress, the reaction center-binding protein D1 of PSII is photo-oxidatively damaged and removed from PSII complexes by proteases located in the chloroplast. A protease considered to be responsible for degradation of the damaged D1 protein is the metalloprotease FtsH. We showed previously that the active hexameric FtsH protease is abundant at the grana margin and the grana end membranes, and this homo-complex removes the photodamaged D1 protein in the grana. Here, we showed a change in the distribution of FtsH in spinach thylakoids during excessive illumination by transmission electron microscopy (TEM) and immunogold labeling of FtsH. The change in distribution of the protease was accompanied by structural changes to the thylakoids, which we detected using spinach leaves by TEM after chemical fixation of the samples. Quantitative analyses showed several characteristic changes in the structure of the thylakoids, including shrinkage of the grana, outward bending of the marginal portions of the thylakoids and an increase in the height of the grana stacks under excessive illumination. The increase in the height of the grana stacks may include swelling of the thylakoids and an increase in the partition gaps between the thylakoids. These data strongly suggest that excessive illumination induces partial unstacking of the thylakoids, which enables FtsH to access easily the photodamaged D1 protein. Finally three-dimensional tomography of the grana was recorded to observe the effect of light stress on the overall structure of the thylakoids.

DOI： 10.1093/pcp/pcu079

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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 2014.6

Language：English Publisher：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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光化学系IIのquality control:光ストレス下でのホウレンソウ葉緑体のグラナ膜構造の変化

難波大介, 西村美保, 坂本浩隆, 村田和義, 高木孝士, 山本泰

日本植物生理学会年会要旨集 55th 328 2014.3

Identification of CNS Neurons Innervating the Levator Ani and Ventral Bulbospongiosus Muscles in Male Rats

Amy D. Dobberfuhl, Takumi Oti, Hirotaka Sakamoto, Lesley Marson

JOURNAL OF SEXUAL MEDICINE 11 ( 3 ) 664 - 677 2014.3

Language：English Publisher：WILEY

IntroductionThe pelvic striated muscles play an important role in mediating erections and ejaculation, and together these muscles compose a tightly coordinated neuromuscular system that is androgen sensitive and sexually dimorphic.
AimTo identify spinal and brains neurons involved in the control of the levator ani (LA) and bulbospongiosus (BS) in the male adult and preadolescent rat.
MethodsRats were anesthetized, and the transsynaptic retrograde tracer pseudorabies virus (PRV) was injected into the LA muscle of adults or the ventral BS muscle in 30-day-old rats. After 3-5 days rats were sacrificed, and PRV-labeled neurons in the spinal cords and brains were identified using immunohistochemistry. The presence of gastrin-releasing peptide (GRP) in the lumbar spinal neurons was examined.
Main Outcomes MeasuresThe location and number of PRV-labeled neurons in the spinal cord and brain and GRP colocalization in the lumbar spinal cord.
ResultsPRV-labeled spinal interneurons were found distributed throughout T11-S1 of the spinal cord, subsequent to dorsal medial motoneuron infection. The majority of spinal interneurons were found in the lumbosacral spinal cord in the region of the dorsal gray commissure and parasympathetic preganglionic neurons. Preadolescent rats had more PRV-labeled spinal interneurons at L5-S1 where the motoneurons were located but relatively less spread rostrally in the spinal cord compared with adults. Lumbar spinothalmic neurons in medial gray of L3-L4 co-localized PRV and GRP. In the brain consistent labeling was seen in areas known to be involved in male sexual behavior including the ventrolateral medulla, hypothalamic paraventricular nucleus, and medial preoptic area.
ConclusionCommon spinal and brain pathways project to the LA and BS muscles in the rat suggesting that these muscles act together to coordinate male sexual reflexes. Differences may exist in the amount of synaptic connections/neuronal pathways in adolescents compared with adults. Dobberfuhl AD, Oti T, Sakamoto H, and Marson L. Identification of CNS neurons innervating the levator ani and ventral bulbospongiosus muscles in male rats. J Sex Med 2014;11:664-677.

DOI： 10.1111/jsm.12418

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W3-02 免疫組織化学法を用いた体性感覚ニューロン系の3次元微細構造解析(W3 Bioimaging histochemistry,ワークショップ,第55回日本組織細胞化学会総会・学術集会第11回日中合同組織細胞化学セミナー)

高浪景子, 坂本浩隆, 宮崎直幸, 村田和義, 佐藤慧太, 坂本竜哉, 河田光博

日本組織細胞化学会総会プログラムおよび抄録集 ( 55 ) 65 - 65 2014

光化学系IIのquality control:光ストレス下でのホウレンソウ葉緑体チラコイド膜構造変化の電子顕微鏡による観察

難波大介, 西村美保, 坂本浩隆, 村田和義, 高木孝士, 山本泰

日本植物学会大会研究発表記録 77th 231 2013.8

光化学系IIのquality control:電子顕微鏡を用いた光ストレス下のホウレンソウ葉緑体のグラナチラコイド膜構造の観察

難波大介, 西村美保, 大庭千加子, 坂本浩隆, 村田和義, 高木孝士, 山本泰

日本植物生理学会年会要旨集 54th 238 2013.3

Potential roles of arginine-vasotocin in the regulation of aggressive behavior in the mudskipper (Periophthalmus modestus)

N. Kagawa

General and Comparative Endocrinology 194 257 - 263 2013

Potential roles of arginine-vasotocin in the regulation of aggressive behavior in the mudskipper (Periophthalmus modestus)

N. Kagawa

General and Comparative Endocrinology 194 257 - 263 2013

超高圧電子顕微鏡を用いたラット脊髄gastrin‐releasing peptide系を中心とした脊髄内局所神経回路の三次元的解析

越智拓海, 佐藤慧太, 齊藤和裕, 村田和義, 河田光博, 坂本竜哉, 坂本浩隆

日本解剖学会総会・全国学術集会講演プログラム・抄録集 118th 167 2013

Three-dimensional evaluation of the spinal local neural network revealed by the high-voltage electron microscopy: a double immunohistochemical study

Takumi Oti, Keita Satoh, Kazuhiro Saito, Kazuyoshi Murata, Mitsuhiro Kawata, Tatsuya Sakamoto, Hirotaka Sakamoto

HISTOCHEMISTRY AND CELL BIOLOGY 138 ( 4 ) 693 - 697 2012.10

Language：English Publisher：SPRINGER

Three-dimensional (3-D) analysis of anatomical ultrastructures is important in biological research. However, 3-D image analysis on exact serial sets of ultra-thin sections from biological specimens is very difficult to achieve, and limited information can be obtained by 3-D reconstruction from these sections due to the small area that can be reconstructed. On the other hand, the high-penetration power of electrons by an ultra-high accelerating voltage enables thick sections of biological specimens to be examined. High-voltage electron microscopy (HVEM) is particularly useful for 3-D analysis of the central nervous system because considerably thick sections can be observed at the ultrastructure level. Here, we applied HVEM tomography assisted by light microscopy to a study of the 3-D chemical neuroanatomy of the rat lower spinal cord annotated by double-labeling immunohistochemistry. This powerful methodology is useful for studying molecular and/or chemical neuroanatomy at the 3-D ultrastructural level.

DOI： 10.1007/s00418-012-0976-6

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光化学系IIのquality control:電子顕微鏡を用いた光ストレス下のホウレンソウ葉緑体のグラナチラコイド膜構造の観察

難波大介, 西村(吉岡)美保, 坂本浩隆, 村田和義, 山本泰

日本植物学会大会研究発表記録 76th 222 2012.9

Brain-spinal cord neural circuits controlling male sexual function and behavior

Hirotaka Sakamoto

Neuroscience Research 72 ( 2 ) 103 - 116 2012.2

Language：English Publishing type：Book review, literature introduction, etc.

Men and women exhibit differences in sexual behavior. This indicates that neural circuits within the central nervous system (CNS) that control sexual behavior differ between the sexes, although differences in behavior are also influenced by sociocultural and hormonal factors. Sexual differentiation of the body and brain occurs during the embryonic and neonatal periods in humans and persists into adulthood with relatively low plasticity. Male sexual behavior is complex and depends on intrinsic and extrinsic factors, including olfactory, somatosensory and visceral cues. Many advances in our understanding of sexually dimorphic neural circuits have been achieved in animal models, but major issues are yet to be resolved. This review summarizes the sexually dimorphic nuclei controlling male sexual function in the rodent CNS and focuses on the interactions of the brain-spinal cord neural networks controlling male sexual behavior. Possible factors that relate findings from animal studies to human behavior are also discussed. © 2011 Elsevier Ireland Ltd and the Japan Neuroscience Society.

DOI： 10.1016/j.neures.2011.11.002

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Achieve orgasm? Oxytocin triggers ejaculation in men

H. Sakamoto

Reproductive System & Sexual Disorders 1 e101-e101 2012

Hemolymph osmotic, ionic status, and branchial Na⁺/K⁺-ATPase activity under varying environmental conditions in the intertidal grapsid crab, Gaetice depressusd

Takeshi Nanba, Hideya Takahashi, Tsukasa Abe, Waichirou Godo, Maho Ogoshi, Hirotaka Sakamoto, Naoaki Tsutsui, Tatsuya Sakamoto

International Aquatic Research 4 ( 1 ) 1 - 12 2012

© 2012, Nanba et al.; licensee Springer. Osmo- and ionoregulatory abilities were examined in the intertidal grapsid crab, Gaetice depressus, transferred from normal seawater (30 ppt) to low (10 ppt) or high (50 ppt) salinities for 2 and 10 days, in addition to animals kept out of water for 2 days. The results of the hemolymph osmotic and ionic status indicate that G. depressus is able to adapt for more than 10 days in these salinities and for 2 days under terrestrial conditions. Especially, the free Ca2+ concentration was relatively maintained compared with concentrations of monovalent ions and osmolality values in 10 and 50 ppt, partly using the complexed calcium (total minus free calcium) as an internal reserve in the hemolymph. In 10 ppt, complexed calcium disappeared from the hemolymph after 10 days, indicating that all the hemolymph calcium was ionized. In 50 ppt, free Ca2+ was regulated to lower levels than concentrations in the medium, while total calcium increased to higher levels after 2 days. Examination of Na+/K+-ATPase activity, which has been implicated in ion transport in many crustaceans, revealed that induction of high Na+/K+-ATPase activity varies among the posterior gills in response to salinities. Ten-ppt salinity induces activity in two of the posterior gills (gill numbers 6 and 7, eight in total), albeit with differing degrees of response. In contrast, 50-ppt salinity stimulates the activity primarily in gill number 8, suggesting that this gill may be associated specifically with ion excretion in G. depressus. As a euryhaline amphibious crab, this abundant species around Japan will serve as a model to study the osmotic/ionic regulatory mechanisms which operate in crustaceans.

DOI： 10.1186/2008-6970-4-18

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Immunohistochemical Analysis of the Effects of Estrogen on Intraarticular Neurogenic Inflammation in a Rat Anterior Cruciate Ligament Transection Model of Osteoarthritis

Atsuhiko Yoshida, Toru Morihara, Ken-ichi Matsuda, Hirotaka Sakamoto, Yuji Arai, Yoshikazu Kida, Mitsuhiro Kawata, Toshikazu Kubo

CONNECTIVE TISSUE RESEARCH 53 ( 3 ) 197 - 206 2012

Language：English Publisher：INFORMA HEALTHCARE

Synovitis is considered as one of the factors associated with the pathogenesis of osteoarthritis (OA). There is currently a significant amount of research linking estrogen deficiencies with the development of OA in estrogen-deficient women, including postmenopausal women; however, the exact etiology remains unclear. Various neuropeptides, such as substance P (SP) and calcitonin gene-related peptide (CGRP), have been shown to contribute to synovitis in OA joints, and the influence of estrogen on the expressions of SP and CGRP in the synovium of OA joints has been noted. After ovariectomy (OVX) followed by estradiol (E2) replacement, 24 female rats were divided into three groups: OVX group, OVX + E2 replacement group (E2 group), and a sham group. All rats underwent transection of the anterior cruciate ligament at the same time. After 30 days, the histological findings of knee joints by hematoxylin-eosin staining and immunofluorescence staining of protein gene product 9.5 (pan-neuronal marker), SP, and CGRP were compared among experimental groups. The degree of synovitis in the OVX group was higher than in the E2 and sham groups. No significant differences in the density of protein gene product 9.5-immunoreactive nerve fibers were observed among the three experimental groups, but the density of SP- or CGRP-immunoreactive nerve fibers in the OVX group was significantly higher than in the E2 and sham groups. These findings suggest that estrogen partly regulates intraarticular neurogenic inflammation in OA joints by modulating the expressions of neuropeptides in the synovium.

DOI： 10.3109/03008207.2011.628059

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A Gastrin-Releasing Peptide (GRP) System in the Spinal Cord Controls Male Sexual Functions

SAKAMOTO H.

85 ( 3 ) 113 - 114 2010.9

Induction of the arginine vasopressin-enhanced green fluorescent protein fusion transgene in the rat locus coeruleus

Miwako Todoroki, Yoichi Ueta, Hiroaki Fujihara, Hiroki Otsubo, Minori Shibata, Hirofumi Hashimoto, Mizuki Kobayashi, Hirotaka Sakamoto, Mitsuhiro Kawata, Govindan Dayanithi, David Murphy, Hisanori Hiro, Ken Takahashi, Shoji Nagata

STRESS-THE INTERNATIONAL JOURNAL ON THE BIOLOGY OF STRESS 13 ( 4 ) 281 - 292 2010.7

Language：English Publisher：INFORMA HEALTHCARE

We examined the effects of intracerebroventricular (i.c.v.) administration of colchicine on the expression of the arginine vasopressin (AVP)-enhanced green fluorescent protein (eGFP) fusion gene in rats. In rats administered i.c.v. vehicle ( control), eGFP fluorescence was observed in the supraoptic nucleus ( SON), the magnocellular division of the paraventricular nucleus (PVN), the suprachiasmatic nucleus (SCN), the median eminence ( ME) and the posterior pituitary. Two days after i.c.v. administration of colchicine, eGFP fluorescence was markedly increased in the SON, the magnocellular and parvocellular divisions of the PVN, the SCN, the ME and the locus coeruleus (LC). Immunohistochemical staining for eGFP confirmed the distribution of fluorescence in both groups. In the colchicines-administered groups, immunohistochemistry for tyrosine hydroxylase (TH) revealed that the eGFP fluorescence was co-localised with TH-immunoreactivity in the LC. Similarly, in situ hybridization histochemistry for eGFP mRNA revealed a significant increase in gene expression in the LC, the SON and the PVN 12-48 h after administration of colchicine. Our results indicate that the synthesis of AVP-eGFP is upregulated in noradrenergic neurones in the LC after colchicine administration. This implies that AVP and noradrenaline, originating from LC neurones, might play a role in response to chronic stress.

DOI： 10.3109/10253890903383406

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Aldosterone-Sensitive Nucleus Tractus Solitarius Neurons Regulate Sensitivity of the Baroreceptor Reflex in High Sodium-Loaded Rats

Tomoharu Masuda, Yasutoshi Hirabara, Yusuke Nakamura, Akiko Chishaki, Mai Tsuruhisa, Masayuki Miyakawa, Kenji Honda, Ryo Saito, Hirotaka Sakamoto, Mitsuhiro Kawata, Yukio Takano

JOURNAL OF PHARMACOLOGICAL SCIENCES 112 ( 4 ) 482 - 486 2010.4

Language：English Publisher：JAPANESE PHARMACOLOGICAL SOC

We examined the role of aldosterone-sensitive neurons in the nucleus tractus solitarius (NTS) in the arterial baroreceptor reflex (baroreflex) function. Baroreflex sensitivity was induced by phenylephrine in high sodium-loaded rats and was significantly reduced. This baroreflex sensitivity was reversed by microinjection of the mineralocorticoid receptor (MR) antagonist eplerenone into the NTS. 11 beta-Hydroxysteroid dehydrogenase type 2 neurons and MR were also identified in the NTS. These data suggest that the aldosterone-sensitive neurons in the NTS may have an important role in baroreflex function.

DOI： 10.1254/jphs.09362SC

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Expression of G protein-coupled receptor 30 in the spinal somatosensory system

Keiko Takanami, Hirotaka Sakamoto, Ken-Ichi Matsuda, Koji Hosokawa, Mayumi Nishi, Eric R. Prossnitz, Mitsuhiro Kawata

BRAIN RESEARCH 1310 17 - 28 2010.1

Language：English Publisher：ELSEVIER SCIENCE BV

Estrogens were originally identified as the primary sex steroid hormones in females and regulators of reproductive function and sexual behavior, but it has long been suggested that estrogens also have local effects on the somatosensory system at the spinal cord level. it is well known that the effects of estrogens are mediated by nuclear estrogen receptors (ERs) through genomic action, but recently a membrane-bound G protein-coupled receptor, GPR30, was identified as a non-genomic estrogen receptor. in this study we investigated the presence and localization of GPR30 in the rat spinal cord and dorsal root ganglion (DRG) in comparison with ER alpha. Using immunohistochemistry and in situ hybridization, we showed the expression of GPR30 in DRG neurons in male and female rats at mRNA and protein levels without specific sexual difference. A dense accumulation of GPR30 immunoreactivity was observed in the outer layer of the spinal dorsal horn, and selective spinal dorsal rhizotomy revealed that GPR30 was transported from the DRG to terminals located in the spinal dorsal horn. GPR30 expression was downregulated in DRG neurons of ovariectomized female rats. The spinal somatosensory system might be modulated by estradiol via putative membrane ER, GPR30-mediated mechanism. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.brainres.2009.11.004

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MISC - SAKAMOTO Hirotaka