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Dive into the research topics where Miwako Sekitani is active.

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Featured researches published by Miwako Sekitani.


Molecular Brain Research | 1989

In situ hybridization analysis of the somatostatin-containing neuron system in developing cerebellum of rats

Shinobu Inagaki; Sadao Shiosaka; Miwako Sekitani; Koichi Noguchi; Shoichi Shimada; Hiroshi Takagi

We used in situ hybridization histochemistry to examine the postnatal development of the somatostatin (SRIF) synthesizing system in the cerebellum of rats. There are numerous hybridizing neurons from 1 to 9 days after birth. These occur throughout the cerebellum including the developing medulla and cortex except in the external granular cell layer. The lateral cerebellar nucleus also contains SRIF gene-containing cells. The intensity of the signals for SRIF mRNA in the cerebellum decreases with age. There is a drastic decrease in SRIF mRNA in the lateral cerebellar nucleus. SRIF cells cannot be detected in the lateral cerebellar nucleus of adult rats, whereas a small, yet significant number of SRIF cells are scattered in the cerebellar medulla. However, the cerebellum of adult rats still contains a significant number of labeled cells in the granular cell layer, although the intensity for SRIF mRNA decreases from 14 days after birth to adulthood. SRIF gene-expressing cells in the cerebellar cortex are located primarily in the granular cell layer and appear to correspond to Golgi cells judging from their characteristic features. These results are consistent with our previous immunohistochemical study on the decrease of SRIF immunoreactivity in the cerebellum of adult rats. These findings, together with a recent study of transient SRIF receptor-expressing cells in the developing cerebellum suggest that SRIF acts during cerebellar development.


Life Sciences | 1988

Little or no induction of hyperglycemia by 2-deoxy-d-glucose in hereditary blind microphthalmic rats

Katsuya Nagai; Miwako Sekitani; Katsumi Otani; Hachiro Nakagawa

Studies were made on whether hereditary microphthalmic rats (1), which are congenitally blind, showed a hyperglycemic response to intracerebroventricular injection of 2-deoxy-D-glucose (2DG) in their subjective light period. In contrast to previous findings in normal rats in which 2DG injection caused light-cycle dependent hyperglycemia (2) and bilateral lesion of the suprachiasmatic nucleus (SCN) completely abolished this hyperglycemia (3), 2DG injection caused no and only slight hyperglycemia in male and female rats with hereditary microphthalmia, respectively. Gross and histological examinations indicated that these rats had no optic nerve or retinohypothalamic tract and that their SCN had an abnormal structure. Locomotive activity recordings showed that all the blind rats had a free-running circadian activity rhythm. These findings suggest that the projection sites of the retinohypothalamic tract to the SCN are involved in the mechanism of the hyperglycemic response to 2DG, but that neural cells, which may be responsible for the generation of circadian rhythms, are not. We have reported that when adult rats were blinded by orbital enucleation, their hyperglycemic response to 2DG was suppressed temporarily 3-5 weeks after the operation, but that their plasma insulin level was basically higher and increased further after 2DG injection during this period (4). In congenitally blind rats, however, the basal plasma insulin level was not higher and the level did not change after 2DG treatment. This difference is discussed from the view point of the role of the premature SCN in regulation of the plasma insulin concentration.


Molecular Brain Research | 1990

Transient expression of somatostatin mRNA in the auditory system of neonatal rat

Miwako Sekitani; Sadao Shiosaka; H. Kuriyama; Yasuhide Lee; Mikako Ikeda; Masaya Tohyama

Postnatal changes of preprosomatostatin mRNA expression in the rat auditory system were examined using in situ hybridization histochemical techniques. It was found that during postnatal days 1 and 2 most of the neurons in the dorsal and ventral cochlear nuclei, and large numbers of neurons in the inferior colliculus, paralemniscal nucleus, and lateral lemniscal nucleus, expressed somatostatin mRNA with a strong intensity. During postnatal development a marked decrease in the number and intensity of neurons expressing somatostatin mRNA was seen. These findings suggested that somatostatin was actively produced in the cochlear nuclei at a very early stage but that production later became reduced or ceased during postnatal ontogeny.


Brain Research | 1990

Electron microscopic observation of calcitonin gene-related peptide-like immunoreactivity in the organ of Corti of the rat

Hiromichi Kuriyama; Sadao Shiosaka; Miwako Sekitani; Y. Tohyama; Masanori Kitajiri; Toshio Yamashita; Tadami Kumazawa; Masaya Tohyama

Calcitonin gene-related peptide (CGRP)-like immunoreactive (CGRP-IR) nerve terminals in the organ of Corti of rats were studied by light and electron microscopy. Surface preparation of the organ of Corti were immunostained using anti-CGRP antiserum for avidin-biotin immunohistochemistry. Dense CGRP-IR fiber bundles were observed by light microscopy in the inner spiral bundles, tunnel spiral bundles and outer spiral bundles. Electron microscopic analysis indicated that CGRP-IR fibers belong to efferent nerves. In the inner spiral bundles, the CGRP-IR fibers showed a direct contact mainly with non-immunoreactive afferent fibers. Some CGRP-IR nerve endings in the inner spiral bundles formed contacts directly with inner hair cells. In the outer spiral bundles, CGRP-IR fibers formed synaptic contacts exclusively with the outer hair cells. It should be noted that the number of synapses of CGRP nerve endings with outer hair cells varied depending upon the sub-row: a falling gradient in number occurred along the inner-outer axis. Our results suggest that CGRP acts as an efferent neuromodulator in the organ of Corti.


Neuroscience Research Supplements | 1992

Three-dimensional distribution of the CGRP-positive perikarya in the trigeminal ganglion of a snake

Tetsuo Kadota; Miwako Sekitani; Richard C. Goris; Toyokazu Kusunoki; Shin-Ichi Terashima


Neuroscience Research Supplements | 1990

Auditory systemElectron microscopic observation of calcitonin gene-related peptide like immunoreactivity in the organs of corti of the rat

Hiromichi Kuriyama; Sadao Shiosaka; Miwako Sekitani; Toshio Yamashita; Tadami Kumazawa; Masaya Tohyama


Neuroscience Research Supplements | 1990

Electron microscopic observation of calcitonin gene-related peptide like immunoreactivity in the organs of corti of the rat

Hiromichi Kuriyama; Sadao Shiosaka; Miwako Sekitani; Toshio Yamashita; Tadami Kumazawa; Masaya Tohyama


Neuroscience Research Supplements | 1990

Immunohistochemical localization of nerve growth factor receptor containing nerve terminals in the rat central nervous system

Miwako Sekitani; Mikako Ikeda; Yasuhide Lee; Sadao Shiosaka; Hiroshi Hatanaka; Masaya Tohyama


Neuroscience Research Supplements | 1989

Somatostatin mRNA in rat developmental cerebellum

Shinobu Inagaki; Sadao Shiosaka; Miwako Sekitani; Masaya Tohyama; Hiroshi Takagi


Neuroscience Research Supplements | 1989

Distribution and postnatal development of somatostatinergic neuron system in rat lower brainstem—In situ hybridization histochemistry

Sadao Shiosaka; Yukituka Kudo; Kazuki Hagihara; Miwako Sekitani; Hiromichi Kuriyama; Masaya Tohyama

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Sadao Shiosaka

Nara Institute of Science and Technology

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Tadami Kumazawa

Kansai Medical University

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Hiroshi Takagi

Nara Institute of Science and Technology

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