Melatonin inhibits the apoptosis of rooster Leydig cells by suppressing oxidative stress via AKT-Nrf2 pathway activation.

Oxidative stress has been described as a key driver of Leydig cell apoptosis. Melatonin has antioxidative and antiapoptotic effects, but the potential effects and mechanism of melatonin on oxidative stress and apoptosis in rooster Leydig cells remain unclear. Our results showed that melatonin biosynthetic enzymes and melatonin receptors were expressed in rooster Leydig cells and their expression were locally inhibited as rooster sexual maturation. We found that melatonin inhibited H2O2-induced apoptosis of rooster Leydig cell by activating the melatonin receptors Mel-1a and Mel-1b. Additionally, melatonin protects mitochondria from damage by reducing the level of oxidative stress in Leydig cells. Melatonin relieved H2O2-induced oxidative stress by significantly reducing intracellular ROS, MDA and 8-OHdG levels and increasing SOD and GSH-Px activities. Simultaneously, melatonin significantly reduced H2O2-induced depolarization of ΔΨm and decreased the release of Cytochrome C and Ca2+. We also observed that melatonin activated the Nrf2 pathway, while Nrf2 silencing abrogated the anti-oxidative and anti-apoptotic effects of melatonin in rooster Leydig cells. Furthermore, melatonin promoted the phosphorylation of AKT, while AKT inhibitor suppressed the Nrf2 pathway activated by melatonin and alleviated the inhibitory effects of melatonin on apoptosis and oxidative stress. In conclusion, melatonin could inhibit apoptosis in rooster Leydig cells by suppressing oxidative stress via activation of the AKT-Nrf2 pathway.