| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1991: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1990: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
The present study was aimed to clarify differentiation, proliferation and development(terminal diffelentiation)of somatotroplis(GH cells)and mammotroptis(PRL cells)of the rat pituitary. The findings obtained in the present study are as follows. (1)GH cells were immunohistochemically detected at 18 days of fetal age, and PRL eells were at 19 days of fetal age. Mammosomato trophs(MS cells), which produced both GH and PRL at the same time, were immunoeIectron microscopicaIIy observed during the postnatal period, although the number of them were quite few. MS cells are considered to be the progenitor cells of both GH cells and PRL cells, or the transitional cells between botti Gil cells and PRL cells. (2)Immunoelectron microscopical study snowed morphological heterogeneity of Gil cells and PRL cells. GH cells and PRL cells were sub-divided into three subtypes, respectively on the basis of the size of secretory granules and the cell shape. The relative proportion of each subtype changed wit
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h age and by several hormonal treatments. These changes are closely correlated with changes in the secretory activities of each cell type. (3)Reverse hemolytic plaque assay snowed functional heterogeneity of GH cells. there were two subpopulations in GH cells : high secretory activity cell and low secretory activity cell. (4)The proliferation of pituitary cells were studied in streptozotocin-induced diabetes rats. The relative proportion of DNA-synthesizing pituitary cells was lower in the diabetic rats than in control rats. Also, response of pituitary cells in the diabetic rats to estrogen on the cell proliferation was low as compared with control rats. Thus, the proliferation of pituitary cells may depend on the insulin level. (5)Age-related changes in GH and PRL mRNA levels were studied. The GH and PRL syntheses at the transcription level decreased in each Gil and PRL cell with aging. Thus, the present study clarified morphological and functional changes in GH cells and PRL cells of rats from the fetal ages to senile ones. Less
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