RESUMEN
The aims of the study were to characterize leptin and it is receptor (LEPR) proteins immunoexpression in ovine ovaries and to evaluate the effects of leptin on development of secondary follicles cultured in vitro. The ovaries were collected and fixed for immunohistochemical analysis. Additional pairs of ovaries were collected and secondary follicles were isolated and cultured, for 18 days, in α-MEM+ alone or supplemented with 10 or 25â¯ng/mL of leptin. The antrum formation and fully grown oocytes rates were higher in 25â¯ng/mL leptin than all treatments. GSH levels and mitochondrial activity were higher in 10 or 25â¯ng/mL leptin than α-MEM+. 25â¯ng/mL leptin showed a higher percentage of MII than the α-MEM+. In conclusion, leptin and its receptor are expressed in ovine ovaries and 25â¯ng/mL leptin promoted higher in vitro maturation rates by improving follicular development, GSH levels and mitochondrial activity of ovine oocytes compared to control medium.