Protective effects of melatonin and IGF-1 against nicotine-induced oxidative stress during in vitro maturation of buffalo oocytes

Nicotine, a principal component of cigarette smoke, elevates Reactive Oxygen Species (ROS), leading to apoptosis, chromosomal instability, and compromised follicular quality, ultimately affecting fertility, oocyte maturation, and pregnancy rates. This study investigated the effects of nicotine and antioxidant supplementation on the in vitro maturation (IVM) of buffalo oocytes. Ovaries were collected from slaughterhouses, and cumulus-oocyte complexes (COCs) were retrieved via slicing. Selected high-quality oocytes were cultured in IVM media containing varying concentrations of nicotine (2, 5, and 10 mM). Maturation rates were evaluated based on cumulus cell expansion. Exposure to 10 mM nicotine resulted in no detectable maturation, while 2 mM and 5 mM nicotine caused significant reductions in maturation rates (20.55% and 7.05%, respectively), compared to controls (84.08%). Supplementation with antioxidants melatonin and insulin-like growth factor 1 (IGF-1) in nicotine-treated oocytes improved maturation rates notably at lower nicotine concentrations. At 10 mM nicotine with antioxidants, maturation was 10.75%, while at 5 mM and 2 mM, rates reached 23.44% and 35.34%, respectively, relative to control (91.10%). These results indicate that antioxidant supplementation can partially counteract nicotine’s detrimental effects, potentially enhancing oocyte quality and maturation in buffalo reproductive biotechnologies.