Immunolocalization of Androgen Receptor in the Small, Preovulatory, and Postovulatory Follicles of Laying Hens

Abstract

Previous studies have indicated that androgens may act directly on the ovarian follicles to regulate their functions. The aim of this study was to localize androgen receptor (AR) in the small, preovulatory and postovulatory follicles of laying hens by an immunocytochemical method and Western blot analysis. Small follicles embedded in the stroma (SF), small white follicles protruding from the surface of ovary (SWF), the third largest (F3) and largest follicles (F1), and the most recent postovulatory follicle (POF) were obtained from hens approximately 4 or 10 hr before the expected time of ovulation. Frozen sections of these follicles were immunostained by using anti-human AR antibody. Furthermore, the granulosa cells and theca tissue of preovulatory follicles (F1 and F2) approximately 4 hr before the expected time of ovulation were processed for western blot analysis for AR. The majority of granulosa cell of SF showed negligible AR immunoreaction, whereas all of the granulosa cells of SWF, F3, F1, and POF exhibited a strong AR immunoreaction. Thecal interstitial ceils in SWF, F3, and F1 stained positive for AR, and those in POF showed only a weak immunoreaction. The thecal fibroblasts of SWF, F3, and F1 also showed a positive AR immunoreaction, whereas those of POF stained weakly. No significant difference in the AR localization in the ovary was observed between 4 and 10 hr before the expected time of ovulation. Western blot analysis indicated that the granulosa cells and thecal tissue contained AR protein of molecular weight of approximately 120,000. These results suggest that ovarian tissues are target sites of androgens and the interaction of AR with androgens may have a role in regulation of the functions of the follicles.