Faculty Profiles - SAKAMOTO Hirotaka

Papers - SAKAMOTO Hirotaka

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

H Sakamoto, K Ukena, K Tsutsui

NEUROSCIENCE LETTERS 322 ( 2 ) 111 - 115 2002.4

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCI 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. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

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Novel cerebellar function: Neurosteroids in the purkinje neuron and their genomic and nongenomic actions

K Tsutsui, K Ukena, H Sakamoto

NEUROPLASTICITY, DEVELOPMENT, AND STEROID HORMONE ACTION 101 - 116 2002

Activity and localization of 3 beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4)-isomerase in the zebrafish central nervous system Reviewed

H Sakamoto, K Ukena, K Tsutsui

JOURNAL OF COMPARATIVE NEUROLOGY 439 ( 3 ) 291 - 305 2001.10

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-LISS

Little information is available for neurosteroidogenesis in the central nervous system (CNS) of lower vertebrates. Therefore, in the present study, we examined the enzymatic activity and localization of 3 beta -hydroxysteroid dehydrogenase/Delta (5)-Delta (4)-isomerase (3 beta HSD), a key steroidogenic enzyme, in the CNS of adult male zebrafish to clarify central progesterone biosynthesis. Biochemical studies together with HPLC analysis revealed that the zebrafish brain converted pregnenolone to progesterone, suggesting the enzymatic activity of 3 beta HSD. This conversion was significantly reduced by trilostane, a specific inhibitor of 3 beta HSD. By using Western immunoblotting with the polyclonal. antiserum. directed against purified bovine adrenal 3 beta HSD, a 3 beta HSD-like substance was found in homogenates of the zebrafish brain. Immunocytochemical analysis was then undertaken to investigate the localization of the 3 beta HSD-like substance in the zebrafish brain and spinal cord. Clusters of immunoreactive cell bodies were localized in the dorsal telencephalic. areas (D), central posterior thalamic nucleus (CP), preoptic nuclei (NPO), posterior tuberal nucleus (PTN), paraventricular organ (PVO), and nucleus of medial longitudinal fascicle (NMLF). 3 beta HSD-like immunoreactivity was also observed in somata of cerebellar Purkinje neurons. A widespread distribution of immunoreactive fibers was found throughout the brain and spinal cord. In addition, positively stained cells were restricted to other organs, such as the pituitary and retina. Preabsorbing the antiserum with purified bovine adrenal microsome resulted in a complete absence of 3 beta HSD-like immunoreactivity. These results suggest that the fish CNS possesses steroidogenic enzyme 3 beta HSD and produces progesterone. The present study further provides the first immunocytochemical mapping of the site of 3 beta HSD expression in the fish CNS. (C) 2001 Wiley-Liss, Inc.

DOI： 10.1002/cne.1351

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Other Link： http://orcid.org/0000-0002-6224-4591

Developmental changes in galanin in lumbosacral sympathetic ganglionic neurons innervating the avian uterine oviduct and galanin induction by sex steroids Reviewed

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

JOURNAL OF ENDOCRINOLOGY 170 ( 2 ) 357 - 368 2001.8

Language：English Publishing type：Research paper (scientific journal) Publisher：SOC ENDOCRINOLOGY

We recently found lumbosacral sympathetic ganglionic galanin neurons innervating the quail uterine oviduct. Galaninergic innervation of the uterine muscle may be essential for avian oviposition, as galanin evoked oviposition through a mechanism of induction of vigorous uterine contraction. The questions arising from these findings are: what changes occur in galanin expression in the sympathetic ganglionic galanin neuron during development, and what is the hormonal Factor(s) that induces galanin expression in this neuron? Therefore, the present study examined the developmental changes in galanin of the quail sympathetic ganglionic neuron and uterus, and the effect of administration of ovarian sex steroids on galanin induction. Immature birds reared under long-day photoperiods from 4 weeks of age demonstrated progressive increases in galanin levels both per unit ganglionic protein (concentration) and per ganglia (content) concurrent with ganglionic development during weeks 4-13. The uterine galanin content and uterine weight also increased progressively during the same period, but the galanin concentration in the uterus at 4 weeks was high due to the much smaller tissue mass. Immunocytochemical analysis with anti-galanin serum showed that immunoreactive ganglionic cells were few and small at 4 weeks and increased progressively thereafter. Administration of oestradiol-17 beta to immature birds at 3 weeks of age for I week increased both the galanin concentration and content in the ganglia without ganglionic growth. A marked increase in galanin-immunoreactive ganglionic cells was detected following oestradiol treatment. In contrast, progesterone increased ganglionic galanin levels, but the effects were low. Expression of the mRNAs encoding oestrogen receptor-alpha and -beta (ER alpha and ER beta) in the ganglionic tissue was verified by RT-PCR/Southern blot analysis. Immunocytochemical staining with anti-ER serum further revealed an intense immunoreaction restricted to the nucleus of ganglionic neurons.
These results suggest that ovarian sex steroids, in particular oestradiol-17 beta, contribute as hormonal factors to galanin induction, which takes place in the lumbosacral sympathetic ganglionic neurons innervating avian uterine oviduct during development. Oestradiol may act directly on this ganglionic neuron through intra-nuclear receptor-mediated mechanisms to induce galanin.

DOI： 10.1677/joe.0.1700357

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Other Link： http://orcid.org/0000-0002-6224-4591

Sympathetic ganglionic galanin neurons evoke avian oviposition by innervating the uterine oviduct: A novel neuronal mechanism of avian oviposition

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

PERSPECTIVE IN COMPARATIVE ENDOCRINOLOGY: UNITY AND DIVERSITY 647 - 653 2001

Language：English Publishing type：Research paper (international conference proceedings) Publisher：MEDIMOND S R L

We recently isolated an oviposition-inducing peptide that was identified as avian galanin from mature quail uterine oviducts. This peptide was localized in neuronal fibers terminating in the uterus, and its receptors were also observed in the uterus. To understand the control mechanism of avian oviposition by galanin, we identified the neurons that synthesize galanin and project to the uterus in mature quails. Retrograde labeling with neurobiotin from the uterus revealed that lumbosacral sympathetic ganglionic neurons projected to the uterine muscle. Colocalization of neurobiotin with galanin-like substance was further confirmed by the ultrastructural immunocytochemistry. Expressions of galanin and its mRNA in the neurons were further confirmed by competitive enzyme-linked immunosorbent assay and Northern blot analysis. These results suggest that lumbosacral sympathetic ganglionic neurons project to the uterine muscle and produce galanin in mature quails.

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Novel brain function: biosynthesis and actions of neurosteroids in neurons Reviewed

K Tsutsui, K Ukena, M Usui, H Sakamoto, M Takase

NEUROSCIENCE RESEARCH 36 ( 4 ) 261 - 273 2000.4

Language：English Publisher：ELSEVIER IRELAND LTD

Peripheral steroid hormones act on brain tissues through intracellular receptor-mediated mechanisms to regulate several important brain neuronal functions. Therefore, the brain is considered to be a target site of steroid hormones. However, it is now established that the brain itself also synthesizes steroids de novo from cholesterol. The pioneering discovery of Baulicu and his colleagues, using mammals, and our studies with non-mammals have opened the door of a new research field. Such steroids synthesized in the brain are called neurosteroids. Because certain structures in vertebrate brains have the capacity to produce neurosteroids identification of neurosteroidogenic cells in the brain is essential to understand the physiological role of neurosteroids in brain functions. Glial cells are generally accepted to be the major site for neurosteroid formation. but the concept of neurosteroidogenesis in brain neurons has up to now been uncertain. We recently demonstrated neuronal neurosteroidogenesis in the blain and indicated that the Purkinje cell, a typical cerebellar neuron, actively synthesizes several neurosteroids de novo from cholesterol in both mammals and non-mammals. Pregnenolone sulfate, one of neurosteroids synthesized in the Purkinje neuron, may contribute to some important events in the cerebellum by modulating neurotransmission. Progesterone, produced as a neurosteroid in this neuron only during neonatal life, may be involved in the promotion of neuronal and glial growth and neuronal synaptic contact ill the cerebellum. More recently, biosynthesis and actions of neurosteroids in pyramidal neurons of the hippocampus were also demonstrated. These serve an excellent model for the study of physiological roles of neurosteroids in the brain, because both cerebellar Purkinje neurons and hippocampal neurons play an important role in memory and learning. This paper summarizes the advances made in our understanding of neurosteroids, produced in neurons, and their actions. (C) 2000 Elsevier Science ireland Ltd and the Japan Neuroscience Society. All rights reserved.

DOI： 10.1016/S0168-0102(99)00132-7

DOI： 10.1016/s0168-0102(99)00132-7

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新しく見いだされた鳥類産卵の神経制御機構:微小脳が合成する産卵誘起ペプチドとその作用機構

筒井和義, 李丹, 坂本浩隆, 浮穴和義

日本比較内分泌学会ニュース = Newsletter of Japan Society for Comparative Endocrinology 96 17 - 22 2000.2

総説 : 神経ステロイドによるシナプス可塑性調節

筒井和義, 浮穴和義, 坂本浩隆

特集:脳のシナプス Brain Medical 12 298 - 306 2000

Reproduction strategy in the minute brain of birds. Egg laying peptide and its mechanism of action.

TSUTSUI Kazuyoshi, LI Dan, SAKAMOTO Hirotaka, UKENA Kazuyoshi

Dobutsu seiri 16 ( 3 ) 191 - 199 1999.9

Posthatching development of spinal motoneurons in the angelfish Pterophyllum scalare Reviewed

M Yoshida, M Fudoji, H Sakamoto, K Uematsu

BRAIN BEHAVIOR AND EVOLUTION 53 ( 4 ) 180 - 186 1999.4

Language：English Publishing type：Research paper (scientific journal) Publisher：KARGER

We investigated the posthatching developmental sequence of spinal motoneurons innervating the axial muscles in the teleost angelfish, Pterophyllum scalare, by means of retrograde labeling with horseradish peroxidase. Two discrete types of spinal motoneurons, primary-type motoneurons and secondary motoneurons were labeled in a temporally different sequence during the course of larval development. These two types of motoneurons were morphologically distinguishable from one other. Primary-type motoneurons are generated by day 1 posthatching and do not increase in number over the observed period (to day 12 posthatching). In contrast, the secondary motoneurons increase in number through posthatching day 3. Differentiation of the spinal motoneurons appears to be nearly complete a few days before the onset of free swimming. In addition, the data suggest that the differentiation of secondary motoneurons precedes the development of the red muscle that is to be innervated by the motoneurons.

DOI： 10.1159/000006593

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