Faculty Profiles - SAKAMOTO Hirotaka

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Dendritic spine formation in response to progesterone synthesized de novo in the developing Purkinje cell in rats

Hirotaka Sakamoto, Kazuyoshi Ukena, Kazuyoshi Tsutsui

Neuroscience Letters 322 ( 2 ) 111 - 115 2002.4

Language：English Publisher：Elsevier Ireland Ltd

The cerebellar Purkinje cell (PC) is a typical site for neurosteroid formation. We have demonstrated that this neuron possesses intranuclear receptor for progesterone and actively synthesizes progesterone de novo from cholesterol only during rat neonatal life, when the formation of the cerebellar cortex occurs dramatically. In this study, we therefore analyzed the effect of progesterone on dendritic spine formation of the PC. In vitro studies using cerebellar slice cultures from newborn rats showed that progesterone increases the density of PC dendritic spines in a dose-dependent manner. This effect was blocked by the progesterone receptor antagonist, RU486. Furthermore, trilostane, a specific inhibitor of progesterone synthesis, inhibited the increase of spine density. These results suggest that progesterone can promote dendritic spine formation, and endogenous progesterone synthesized de novo in the developing PC may induce such an effect. © 2002 Elsevier Science Ireland Ltd. All rights reserved.

DOI： 10.1016/S0304-3940(02)00077-0

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Organizing Actions of Neurosteroids Synthesized De Novo in the Cerebellar Purkinje Neuron

SAKAMOTO Hirotaka

Memoirs of the Faculty of Integrated Arts and Sciences, Hiroshima University. IV, Science reports : studies of fundamental and environmental sciences 28 141 - 144 2002

ACTIVITY AND LOCALIZATION OF 3β-HYDROXYSTEROID DEHYDROGENASE/Δ^5-Δ^4- ISOMERASE IN THE ZEBRAFISH BRAIN

SAKAMOTO Hirotaka, UKENA Kazuyoshi, TSUTSUI Kazuyoshi

16 23 - 23 2001.12

SEX STEROIDS SYNTHESIZED DE NOVO IN THE DEVELOPING PURKINJE NEURON PROMOTE DENDRITIC GROWTH DURING CEREBELLAR CORTICAL FORMATION

MEZAKI Yukio, SAKAMOTO Hirotaka, UKENA Kazuyoshi, TSUTSUI Kazuyoshi

16 26 - 26 2001.12

Effects of progesterone synthesized de novo in the developing Purkinje cell on its dendritic growth and synaptogenesis

坂本浩隆他

J. Neurosci. 21:6221-6232 2001

Activity and localization of 3β-hydroxysteroid dehydrogenase/Δ5-Δ4-isomerase in the zebrafish central nervous system

坂本浩隆他

J. Comp. Neurol. 439:291-305. 2001

Existence of galanin in lumbosacral sympathetic ganglionic neurons that project to the quail uterine oviduct

H Sakamoto, T Ubuka, C Kohchi, D Li, K Ukena, K Tsutsui

ENDOCRINOLOGY 141 ( 12 ) 4402 - 4412 2000.12

Language：English Publisher：ENDOCRINE SOC

Oviposition in birds is conducted by vigorous contractions of the uterine oviduct. We recently isolated an oviposition-inducing peptide that was identified as avian galanin from mature quail oviducts. This peptide was localized in neuronal fibers terminating in muscle layers in the uterine oviduct and evoked vigorous uterine contractions through binding to receptors located in the uterus. However, no cell bodies that express avian galanin were detected in the uterus or other oviduct regions. To understand the control mechanism of avian oviposition by galanin, me identified the neurons that synthesize galanin and project to the uterus with the combination of retrograde labeling with neurobiotin and immunocytochemistry for galanin in mature Japanese quails. Retrograde labeling with neurobiotin from the uterus revealed that lumbosacral sympathetic ganglionic neurons located in the uterine side projected their axons to the uterine muscle layer. Abundant elementary granules were observed in somata of the retrogradely labeled sympathetic ganglionic neurons, suggesting that labeled neurons may function as a neurosecretory cell. Immunocytochemical analysis with the antiserum against avian galanin showed an intense immunoreaction restricted to somata of the retrograde-labeled ganglionic neurons. Preabsorbing the antiserum with avian galanin resulted in a complete absence of the immunoreaction. Competitive enzyme-linked immunosorbent assay using antigalanin serum confirmed that avian galanin existed in the sympathetic ganglionic neurons. Expression of the avian galanin messenger RNA in the neurons was further verified by Northern blot analysis. In addition, both avian galanin and its messenger RNA in the neurons were highly expressed in mature birds, unlike in immature birds.
These results suggest that lumbosacral sympathetic ganglionic neurons innervating the uterine muscle produce avian galanin in mature birds. Because this peptide acts directly on the uterus to evoke oviposition through a mechanism of the induction of vigorous uterine contraction, galaninergic innervation of the uterine oviduct may be essential for avian oviposition.

DOI： 10.1210/en.141.12.4402

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腰仙椎交感神経節ニューロンにおける産卵誘起ペプチドの発現と発達過程における変動

産賀崇由, 坂本浩隆, 河内千恵, 浮穴和義, 筒井和義

日本動物学会中国四国支部会報 ( 52 ) 2000

鳥類の腰仙椎交感神経節ニューロンにおける産卵誘起ペプチドの発現と性ステロイドによる誘導

産賀崇由, 坂本浩隆, 浮穴和義, 筒井和義

Annual Meeting of Japanese Avian Endocrinology 25th 2000

交感神経節ニューロンにおける産卵誘起ペプチドの発現と性ステロイドによる誘導

産賀崇由, 坂本浩隆, 浮穴和義, 筒井和義

日本動物学会大会予稿集 71st 2000

Development of the myotomal neuromuscular system in embryonic and larval angelfish, Pterophyllum scalare

H Sakamoto, M Yoshida, T Sakamoto, K Uematsu

ZOOLOGICAL SCIENCE 16 ( 5 ) 775 - 784 1999.10

Language：English Publisher：ZOOLOGICAL SOC JAPAN

To reveal the developmental sequence of the myotomal neuromuscular system in a teleost angelfish, Pterophyllum scalare, we investigated the differentiation and axonal outgrowth of the somatic spinal motoneurons as well as the differentiation of the axial muscles by means of anatomical and histochemical methods. Acetylcholinesterase histochemistry and retrograde labeling with HRP revealed two large motoneurons in each spinal hemisegment in the late embryos. To clarify the posthatching change of the motoneuron number, the number of axons in the anal-level ventral root was counted, since ChAT-immunohistochemical labeling of cholinergic spinal neurons and electron microscopic observation in the adult showed that the ventral roots around the anal level contained only somatic motor axons. We found that 15 primary motoneurons in each spinal hemisegment participated in the muscle innervation in just-hatched larvae. The motor axons rapidly increased in number beyond the adult level within three days posthatching, and then decreased to reach the adult level within a few weeks. The result suggests that competition among the motoneurons for their target muscles takes place. To reveal the temporal sequence of differentiation of the myotomal muscle fibers, in addition to electron microscopic observation of the muscle, a fluorescent mitochondrial marker dimethylaminostyrylethylpyridiniumiodine (DASPEI) was used to detect red muscle fibers. In the late embryo, immature white muscle fibers subserving the twitching movement of the animal in the egg capsule were observed. Differentiation of the red muscle was not evident until day 10. The present results show that a complete set of the axial muscle motoneurons differentiates before the differentiation of the multiple muscle fiber types in the angelfish.

DOI： 10.2108/zsj.16.775

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Naturally occurring somatic motoneuron death in a teleost angelfish, Pterophyllum scalare

H Sakamoto, M Yoshida, K Uematsu

NEUROSCIENCE LETTERS 267 ( 2 ) 145 - 148 1999.5

Language：English Publisher：ELSEVIER SCI IRELAND LTD

Naturally occurring somatic motoneuron death in a teleost angelfish, Pterophyllum scalare, was investigated histochemically and electron microscopically. The number of motor axons in the ventral root, which corresponds to the motoneuron number in spinal hemisegment, was rapidly increased beyond the adult value within 3 days after hatching, and then decreased to reach the adult value within a few weeks. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) histochemistry, which detects fragmented nuclear DNA characteristic to apoptotic cells, showed that the apoptotic cells are located in the motor column of the cord in the larvae at specific developmental stages. Electron microscopic observations of the spinal cells further confirmed the motoneuron apoptosis. The present data suggest that the massive death of somatic motoneurons at certain ontogenic stages which has been known to occur in higher vertebrates also takes place in fish. (C) 1999 Elsevier Science ireland Ltd. All rights reserved.

DOI： 10.1016/S0304-3940(99)00353-5

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DEVELOPMENT OF SPINAL MOTONEURONS INNERVATING THE AXIAL MUSCULATURE IN EMBRYONIC AND LARVAL ANGELFISH(Physiology)(Proceedings of the Sixty-Ninth Annual Meeting of the Zoological Society of Japan) :

Sakamoto H., Sakamoto T., Yoshida M., Uematsu K.

Zoological science 15 101 - 101 1998

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