ACTH induced differential changes in the steroidal hormones secretion in the wall of bovine antral and cystic follicles.

ORTEGA HH; AMWEG A; PAREDES A; SALVETTI NR; LARA HE

Pittsburgh, Pennsylvania, Estados Unidos de Norteamérica. 18 al 22 de Julio de 2009.

Congreso; 42nd Annual Meeting of the Society for the Study of Reproduction “Science for the Public Good”.; 2009

Cystic ovarian disease (COD) is one of the most common causes of reproductive failure in cattle, and the mechanisms that lead to the development of follicular cysts have been the object of speculation and research for many years, but  they are still little understood. It is believed that COD has a multifactorial etiology, and has been reported that follicular cysts are caused by an endocrine imbalance in the hypothalamo -hypophyseal-gonadal axis, with possible participation of stress as an important factor incorporating to the adrenal gland in this axis. Adrenocorticotropic hormone (ACTH) has been demonstrated to be an important stress response factor, and its levels increase as a consequence of exposing animals to stressors. In this sense, we hypothesize that ACTH can also affect follicular components altering the normal steroid secretion directly, as a differential steroid synthesis mechanism may be present in follicular cyst.  To test this hypothesis, fragments of ovarian follicular wall of large antral and spontaneous cystic follicles were cultured in serum free medium for a 20min, after which tissues were placed in medium with ACTH (1x10-9, 1x10-81 and 1x10-7 UI/ml). Previously, the levels of steroid (estradiol, progesterone, testosterone and cortisol) in follicular fluid were analyzed by enzyme immunoassay. After three hours of incubation, the culture medium was separated and the steroid hormones were analyzed and compared with basals levels without ACTH stimulation. In all cases, basal levels of steroids secretion were detected. In the analysis of culture medium of large antral follicles steroid levels, a significantly dose-dependent increase in testosterone was observed. Also, in cystic follicles, higher values of cortisol, testosterone and estradiol were observed in response to ACTH stimulation. A differential response of cysts in relation to large antral follicles was observed in the secretion of cortisol and estradiol. Our results indicate that ACTH may affect the steroid secretion in bovine ovarian follicles and that follicular cysts have a differential response, unlike that of healthy follicles. These findings support the notion that stress affects the ovarian function and that this can be an important etiological factor of COD in bovines. Also, based on the evidence presented, we propose to consider follicular cells as a potential target for ACTH. (Supported by APCyT grants PICT-2007-01193  BID 1728 OC/AR).