PITUITARY HORMONE-PRODUCING CELLS AFTER ESTRADIOL APPLICATION IN THE RAT MODELS OF MENOPAUSE
Abstract
Female aging represents the biological process of structural and functional changes in endocrine cells and tissues, as well as in the pituitary hormone-producing cells. Besides the hypothalamic releasing hormones, estradiol plays the significant role in regulation of pituitary hormones synthesis/secretion, and it is still used for menopausal symptoms therapy. The effects of aging or ovariectomy, and synthetic estradiol application under these circumstances were evaluated in pituitary hormone-producing cells of female rats (animal models of menopause), i.e. observing the following cells: gonadotropes (FSH and LH), thyrotropes (TSH), somatotropes (GH), mammotropes (PRL) and corticotropes (ACTH). The cells were immunostained and histologically analyzed, while the ELISA method was used for hormonal analyses. Aging was found to cause diverse, commonly reductive changes regarding the volume, number and secretion of menopausal rat pituitary hormone-producing cells, except for the PRL cells that have significantly increased number and intesified secretion. After the treatment of middle-aged female rats with estradiol, absolute and relative pituitary weights are significantly increased in comparison with the control females. Histological parameters like the cell and volume density of PRL and ACTH cells are significantly increased compared to the control values. The mentioned parameters of FSH, LH and GH, and ocassionaly of TSH cells after estradiol treatment are significantly decreased in comparison with the controls. The corresponding hormone levels follow the changes in histological parameters. These data indicate that the estradiol application to menopausal females may specifically, in two directions, modify the histological characteristics and secretory activity of different pituitary-hormone producing cells.
Key words: female rat, middle-age, pituitary cells, estradiol.
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