Melatonin Alleviates MBP-Induced Oxidative Stress and Apoptosis in TM3 Cells via the SIRT1/PGC-1α Signaling Pathway

This study investigates the role of melatonin in alleviating the oxidative stress and apoptosis of TM3 Leydig cells induced by 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), the primary active metabolite of Bisphenol A, and clarifies its potential mechanisms involving the SIRT1/PGC-1α pathway. We found that melatonin effectively mitigated MBP-induced cytotoxicity in TM3 cells (<i>p</i> < 0.05). The testosterone levels and steroid hormone synthesis proteins were significantly restored by melatonin. Furthermore, there was a significant reduction in apoptosis after melatonin treatment both in MBP-treated TM3 cells and Bisphenol A-treated testicular interstitial tissues (<i>p</i> < 0.05), along with a significant decrease in the pro-apoptotic markers Bax and cleaved caspase 3, and a significant increase in the anti-apoptotic Bcl-2 level and the Bcl-2/Bax ratio in TM3 cells (<i>p</i> < 0.05). Additionally, the mitochondrial membrane potential improved significantly, ROS and MDA levels were down-regulated, and ATP production was elevated following melatonin treatment in TM3 cells. Mechanistically, melatonin promoted PGC-1α expression and activated the SIRT1 signaling pathway in MBP-treated TM3 cells and Bisphenol A-treated testicular interstitial tissues. This leads to increased expression of NRF2 and its downstream antioxidant genes, mitochondrial respiratory chain complex-related genes, mitochondrial biogenesis genes, and mitochondrial fusion genes while significantly reducing mitochondrial fission genes (<i>p</i> < 0.05). The PGC-1α inhibitor SR-18292 reversed these protective effects, confirming the critical role of this pathway. Conclusively, melatonin exerts a protective effect against MBP-induced oxidative stress and apoptosis in TM3 cells through the SIRT1/PGC-1α pathway, indicating its potential as a therapeutic agent for improving male reproductive health compromised by environmental toxins.