Proliferation of Pituitary Cells in Streptozotocin-induced Diabetic Mice : Effect of Insulin and Estrogen

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Insulin has growth-stimulatory actions in various tissues. The present study is aimed to clarify whether insulin stimulates the proliferation of anterior pituitary cells. Estrogen is the mitogenic factor in pituitaries and female reproductive tracts. We studied the insulin-estrogen relationship in the pituitary cell proliferation. The proliferation of uterine epithelial cells was also studied , since the uterus was one of the most typical estrogen-responsive organs. Ovariectomized ICR mice were given streptozotocin (STZ, 100mg/kg) intraperitoneally to make mice insulin-deficient. Estradiol-17 β (50μg, E2) and insulin (0.2 or 0.4 IU per twice a day) were given in STZ-treated mice. Insulin significantly stimulated the mitosis of pituitary cells and PRL cells in both normal control mice and STZ-treated diabetic mice. E_2 stimulated the mitosis of pituitary cells (10.93±0.73 cells/mm^2), compared with controls (3.59±0.67 cells/mm^2) in control mice. In STZ-treated mice E2 failed to increase the mitosis (4.91±0.99 cells/mm^2), compared with controls (2.47±0.43 cells/mm^2). Insulin recovered the diminished response to estrogen in pituitary cells of STZ-treated mice to the level comparable to control mice. In the uterus insulin at the high dose used stimulated the proliferation of luminal epithelial cells in normal control mice. However, insulin deficiency did not alter the responsiveness of uterine epithelial cells to estrogen. The present study suggests that insulin is involved in the proliferation of pituitary cells and probably uterine luminal epithelial cells, but the mechanism of insulin action on the cell proliferation may differ between pituitary cells and uterine cells.
社団法人日本動物学会の論文
1994-06-15

Proliferation of Pituitary Cells in Streptozotocin-induced Diabetic Mice : Effect of Insulin and Estrogen

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