Melatonin inhibits apoptosis in mouse Leydig cells via the retinoic acid-related orphan nuclear receptor alpha/p53 pathway

Melatonin is an endogenous indoleamine hormone involved in various physiological processes. However, the mechanism of melatonin in mediating Leydig cells function has not been fully explained. In this study, we investigated the mechanism through which melatonin inhibits apoptosis in mouse Leydig cells by activating the retinoic acid-related orphan nuclear receptor (ROR) alpha/p53 signaling pathway. We confirmed the expression and localization of ROR alpha in mouse Leydig cells using immunofluorescence. After treatment with 10 ng/mL melatonin for 36 h, ROR alpha mRNA and protein levels were significantly increased (P < 0.01). TUNEL and flow cytometry showed that melatonin significantly decreased the TUNEL-positive cell ratio and apoptosis rate (P < 0.05). Moreover, melatonin decreased BAX expression and increased BCL-2 expression (P < 0.05). However, the ROR alpha inhibitor SR1001 reversed the inhibitory effects of melatonin on apoptosis (P < 0.05). Additionally, analysis of p53 expression showed that melatonin inhibited p53 mRNA and protein expression (P < 0.05), whereas SR1001 reversed these effects. p53 reversed the anti-apoptotic process involving ROR alpha-mediated melatonin in mouse Leydig cells. Collectively, our findings suggested that melatonin inhibited apoptosis via the ROR alpha/p53 pathway.