EFFECTS OF ESTRADIOL ON GnRH RECEPTOR SIGNALING PATHWAY AND LH RELEASE IN THE SOUTH AMERICAN PLAINS VIZCACHA (Lagostomus maximus).

PROIETTO S, CORTASA S, SCHMIDT AR, CORSO MC, INSERRA PIF, DI GIORGIO NP, LUX-LANTOS V, HALPERIN J, VITULLO AD, DORFMAN VB

Mar del Plata

Congreso; LXIII Reunión Científica Anual de la Sociedad Argentina de Investigaciones Clínicas; 2018

Sociedad Argentina de Investigaciones Clínicas

Pituitary expression of gonadotropin-releasing hormone (GnRH) receptor (GnRHR) is regulated by estradiol mainly through its receptor ERalpha. The activation of GnRHR pathway involves the induction of transcription factors such as Egr-1 and Sf-1, resulting in luteinizing hormone (LH) expression. Vizcachas show reproductive axis activity during gestation with increased LH delivery at mid-pregnancy. The aim of this work was to determine the effect of estradiol on the GnRH signaling pathway and its final target LH. Adult vizcachas were used under two experimental conditions: 1) Non-pregnant females (NPf); 2) Ovariectomized NPf (OVX) treated with low (OVX-5) or high (OVX-15) doses of estradiol (5ug/kg or 15ug/kg, respectively). SHAM females were used as control (n=4/group). The success of estradiol treatments was corroborated by serum estradiol measure by ELISA. Pituitary LH pulsatility was assayed with or without GnRH supplementation and LH released measured by RIA, whereas pituitary GnRHR, ERalpha, Egr-1 and Sf-1 were studied by immunohistochemistry and PCR. A significant induction of LH release was determined in pituitaries of NPf supplemented with GnRH (p