ACTIVATION OF E2-DEPENDENT PITUITARY PROGESTERONE RECEPTOR ENHANCES THE EFFECT OF GnRH ON LH SURGE IN Lagostomus maximus

PROIETTO S1,2, SCHMIDT AR1,3, CORTASA S1,2, CORSO MC1, INSERRA PIF1,2, FEEHAN, K1, DI GIORGIO NP2,3, LUX-LANTOS V2,3, VITULLO AD1,2; HALPERIN J; DORFMAN BERTA VERONICA

Mar del Plata

Congreso; LXIV Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica.; 2019

Sociedad Argentina de Investigación Clínica

During estral cycle,massive release of pituitary luteinizing hormone (LH) isrequired for the ovulatory event to occur. This is regulated by gonadotropin-releasing hormone (GnRH) and ovarian hormones, estrogen and progesterone (P4). Ovarian P4 enhances the positive feedback of estrogen on GnRH and finally in the LH surge, suggesting that this hormone is also involved in the release of LH.Vizcachas have shown reproductive axis activity during gestation with release of ovarian and hypothalamichormones and an increased LH surge at mid-pregnancy. The aim of this work wasto determine the effects of estradiol (E2) on GnRH receptor (GnRHR),P4 receptors (PR) and LH.Pituitaries of non-pregnant vizcachas were cultured under different conditions: 1)Buffer, 2)E2, 3)GnRH and 4)GnRH plusE2. Secondly, other group of non-pregnant femaleswere ovariectomized (OVX) and treated with E2 (OVX+E2,5ug/kg); (n=4/group). Finally, pituitaries of non-pregnant females were probed in a pulsatilexperiment under three experimental conditions: 1)Buffer, 2)P4, 3)P4+RU486 (PR antagonist).LH releasewas measured by RIA, whereas pituitary GnRHR, ERalpha and PR expression was studied by immunohistochemistry and Western Blot.A significant induction of LH release was determined in pituitary cultures supplemented with GnRH and E2 (p