Effect of supplementing additives in leptin-enriched maturation medium during in vitro maturation and vitrification of goat oocytes

The present study aimed to evaluate the effect of supplementing epidermal growth factor EGF , insulin-like growth factor-I IGF-I , fetal bovine serum FBS , and bovine serum albumin BSA in different combinations in a maturation medium MM comprising TCM-199 + 5 µg/mL 17-β estradiol + 5 µg/mL ovine-luteinizing hormone oLH + 5 µg/mL pure follicle-stimulating hormone pFSH + 100 µM/mL cysteamine containing the best concentration of leptin among 10/20/25/30 ng/mL on in vitro maturation IVM and subsequent vitrification of matured goat oocytes. The IVM of oocytes was carried out in a CO2 incubator for 27 h at 38.5 °C. The percentage of oocytes with cumulus expansion and polar body extrusion was found to be highest in 25 ng/mL leptin at 47.37% and 15.63%; rates of 66.67% and 28.57% were obtained when supplemented with 50 ng/mL IGF-I + 10 ng/mL EGF in medium containing 25 ng/mL leptin as compared to the other media. The in vitro matured oocytes were vitrified in 5 M ethylene glycol + 5 M propylene glycol with 0.5 M sucrose in TCM-199 + 20% FBS using liquid nitrogen. The highest percentage of morphologically intact in vitro matured oocytes following vitrification was obtained in medium containing 25 ng/mL leptin 89.29% . It was concluded that addition of IGF-I + EGF with 25 ng/mL leptin in MM yielded a higher rate of maturation of oocytes, and supplementation of 25 ng/mL leptin in MM resulted in a higher rate of morphologically intact vitrified oocytes, indicating the efficiency of leptin for cryotolerance.