| Co-Investigator(Kenkyū-buntansha) |
UCHIBORI Masayuki Assistant Zoological Institute, Fsculty of Science, Hiroshima Univ., 理学部, 助手 (70106798)
TSUTSUI Kazuyoshi Assistant Zoological Institute, Faculty of Science, Hiroshima Univ., 理学部, 助手 (20163842)
TAKAHASHI Sumio Assistant Zoological Institute, Faculty of Science, Hiroshima Univ., 理学部, 助手 (90144807)
MACHIDA Takeo Associate Professor Zoological Institute, Faculty of Science, Hiroshima Univ., 理学部, 助教授 (70073020)
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| Research Abstract |
The mechanism of maturation and aging of the hypothalamus, pituitary and peripheral endocrine organs has been studied during the last three years by means of various techniques including cell culture, radioreceptor assay, radioimmunoassay, electron microscopy and immunocytochemistry. Important conclusions arrived at in individual research titles which as a whole comprise the present project are summarized as follows.
1. Steroidal effects on the development of sexual dimorphism. Estradiol and testosterone stimulated the neuronal process growth and sprouting in cells derived from the hypothalamus-preoptic area of fetal and neonatal rats in monolayer culture, while dihydrotestosterone was not effective. This indicates the importance of aromatization of testosterone to estrogen for the manifestation of sexual dimorphism of the brain.
2. Neuronal aging. Lipofuscin storage as a parameter of aging of neurons in culture was inhibited by tocopherol and its derivatives. For another parameter of neuronal aging, plasticity of neurosecretory neurons was studied. After hypophysectomy in mice, the increase in the number of fibers in the external layer of the median eminence was greater in young than old animals, suggesting a decrease in axonal plasticity in old mice.
3. Prolactin cells and secretion. Differentiated prolactin cells underwent mitosis in male and femela rats, but sexual difference was present in the prolactin cell population and mitotic activity throughout most of the postnatal life.
4. Regulatory mechanism of gonadotropin receptors. The use of hypophysectomized animals showed that follicle stimulating hormone (FSH) is needed for the induction of FSH receptors. However, in mice after puberty hypophysectomy increased FSH receptors and FSH administration reduced them, suggesting the role of downregulation. This finding was reinforced by electron microscopic autoradiography.
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