Expression of steroidogenic enzymes in porcine polycystic ovaries.

Abstract

In the present study the expression pattern of the cholesterol side-chain cleavage cytochrome (P450(scc)), 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and aromatase (P450(arom)) was analyzed in the health and polycystic ovaries of gilts by means of the Western blot and immunohistochemistry. The polycystic status of ovaries was induced by i.m. dexamethasone (DXM) injections on days 7-21 of the estrous cycle. Macroscopic observation of ovaries of DXM-treated gilts revealed the presence of cysts (1-2 cm in diameter, with a mean number of 7.0+/-1.2 per ovary), a decrease (P<0.05) in number of small follicles (1-3 mm in diameter), as well as the lack of medium-sized follicles (4-6 mm in diameter) and corpora lutea, as compared to the control animals. The expression of P450(scc) (P<0.01), 3beta-HSD (P<0.05) and P450(arom) (P<0.001) proteins in the cysts was higher than in the medium-sized follicles of the control gilts. Moreover, DXM injections resulted also in an enhancement (P<0.05) in the level of P450(scc) protein in the walls of small follicles as compared to the control gilts. Following DXM administration the immunoreactivity (IR) of P450(scc) in the primordial follicles was lower than in the control group. Comparing to the control gilts, the reaction for this enzyme in DXM-treated animals was observed in secondary follicles, while for 3beta-HSD, in primordial, primary, as well as secondary follicles. The immunostaining for P450(scc) (theca cells) and P450(arom) (granulosa cells) in the small follicles of the DXM-treated gilts were more prominent than those found in the gonads of control animals. However, IR for P450(scc) was not found in the granulosa cells of small follicles in the gilts receiving DXM. The intensity of P450(scc) and P450(arom) labelling was distinctly enhanced in the cysts as compared to the medium follicles of the control animals. Furthermore, in contrary to the medium follicles of the control animals, faint IR for 3beta-HSD was found in the granulosa cell layer of cysts. Our data revealed that both the expression of P450(scc), 3beta-HSD and P450(arom) and localization of these enzymes in polycystic ovaries were different from those, found under physiological conditions. These results suggested that above-mentioned enzymes may, by influencing the ovarian steroid synthesis, play an essential role in the creation and/or course of cystic ovarian disease.