Hormon-produkujuće ćelije hipofize nakon primene estradiola u animalnom modelu menopauze

Abstract

Female ageing represents the biological process of structural and functional changes in endocrine cells and tissues, as well as in pituitary hormone-producing cells. In addition to the hypothalamic releasing hormones, estradiol plays a significant role in the regulation of the synthesis/secretion of pituitary hormones and is still used therapeutically for menopausal symptoms. The effects of ageing 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., the following cells were observed: gonadotropes (FSH and LH), thyrotropes (TSH), somatotropes (GH), mammotropes (PRL) and corticotropes (ACTH). The cells were immunostained and histologically analysed. The ELISA method was used for hormonal analyses. Ageing was found to cause diverse, commonly reductive changes regarding the volume, number and secretion of menopausal rat pituitary hormone- producing cells, except for PRL cells that exhibit significantly increased numbers and intensified secretion. After the treatment of middle-aged female rats with estradiol, the absolute and relative pituitary weights significantly increased in comparison with the control females. Histological parameters such as the cell and volume density of PRL and ACTH cells were significantly increased compared with the control values. The mentioned parameters of FSH, LH, GH, and occasionally TSH cells after estradiol treatment significantly decreased in comparison with the controls. The corresponding hormone levels followed the changes in the histological parameters. These data indicate that the application of estradiol to menopausal females may specifically, in two directions, modify the histological characteristics and secretory activities of different pituitary-hormone producing cells.

Starenje kod ženskog pola je biološki proces tokom kojeg dolazi do promena u strukturi i funkciji endokrinih ćelija i tkiva, a posebnu osetljivost ispoljavaju hipofizne hormonprodukujuće ćelije. Pored oslobađajućih hormona hipotalamusa i estradiol ostvaruje zapaženu ulogu u regulaciji sinteze i sekrecije hipofiznih hormona, a još uvek se koristi u terapiji menopauzalnih tegoba. Efekti starenja ili ovarijektomije, kao i primene sintetskog estradiola pod tim okolnostima su ispitivani na hormon-produkujućim ćelijama hipofize ženki pacova srednjeg doba (animalni modeli menopauze) i to: gonadotropima (FSH i LH), tirotropima (TSH), somatotropima (GH), mamotropima (PRL) i kortikotropima (ACTH). Sve ćelije su imunohistohemijski bojene i histološki analizirane, dok je za određivanje nivoa hormona u krvi korišćena ELISA metoda. Utvrđeno je da starenje prouzrokuje različite, uglavnom reduktivne promene volumena, broja i sekrecije hormon-produkujućih ćelija hipofize u našim animalnim modelima menopauze, izuzev na primeru PRL ćelija čiji je broj značajno povećan, a sekrecija intenzivirana. Posle tretmana ženki pacova srednjeg doba estradiolom apsolutna i relativna masa hipofize je značajno povećana u poređenju sa kontrolnim ženkama. Histološki parametri poput volumena ćelija i volumenske gustine PRL i ACTH ćelija su značajno povećani u poređenju sa kontrolnim vrednostima. Sa druge strane, pomenuti parametri u FSH, LH i GH, a u izvesnim slučajevima i TSH ćelijama su značajno smanjeni nakon tretmana estradiolom, u poređenju sa kontrolama. Koncentracije odgovarajućih hormona u krvi su pratile navedene promene histoloških parametara. Ova zapažanja ukazuju da estradiol davan menopauzalnim jedinkama ženskog pola može na specifičan način, dvosmerno, modifikovati histološke karakteristike i sekretornu aktivnost različitih hormon-produkujućih ćelija hipofize.