Expressão de fatores reguladores da apoptose, leptina e seu receptor em complexos cumulus-oócito de ovinos

Abstract

Factors regulating apoptosis can determine the oocyte viability; however there are few studies about the genes of these factors and their action in the antral follicles cumulus-oocyte complex (COC) development, neither about the relationship with Leptin (LEP) and its receptor (LEPR) in sheep. The aim of this study was evaluate the mRNA expression of LEP, LEPR, and the apoptotic regulating factors (Bcl-2, Bax, p53 and caspase 3), in oocytes (OO) and cumulus cells (CC) from different sizes of antral follicles. Twenty pools of OO (20 unities) and of CC (from 20 COC) harvested from follicles > 3 mm and ≤ 3 mm were evaluated. The gene expression was determined after mRNA extraction and further cDNA amplification by real time PCR. Bcl2, p53 and caspase 3 genes were expressed in all cells and follicles size. Bax expression was observed only in OO. LEP and LEPR were expressed only in CC. The expression of apoptosis promoting factors was higher in OO > 3mm, while Bcl2 (anti-apoptotic) expression was higher in OO ≤ 3 mm. Comparing OO with CC from the same size of follicles, there was higher expression of Bcl2 in OO ≤ 3 mm, and lower expression of p53 in OO > 3mm. LEPR tended to be more expressed in CC > 3mm than ≤ 3 mm. Was observed a positive correlation between p53 and BAX expression in OO (r = 0.66), and between Bax in OOs and LEPR in CCs (r = 0.64). It was concluded that the expression of anti- and pro-apoptotic genes in COC can be related to the follicle and oocyte development, since follicles ≤ 3 mm presented lower expression of factors promoting apoptosis. Additionally, leptin can be a regulatory factor of oocyte development due presence of LEPR in CC.