Melatonin counteracts Iodoacetic acid induced ferroptosis by regulating Nrf2 in porcine oocytes

Environmental contaminants pose a significant threat to mammalian reproduction by disrupting follicular development and oocyte maturation. Iodoacetic acid (IAA), an unregulated disinfection byproduct (DBP) found in drinking water, has been shown to impair oocyte maturation in mice, but its effects and underlying mechanisms in porcine oocytes remain unclear. Previous studies have shown that IAA is an unregulated disinfection byproduct in drinking water and can impair oocyte maturation in mice, its impact on follicular development and oocyte maturation in pigs has yet to be elucidated. In this study, porcine oocytes were treated with environmentally relevant concentrations of IAA (1 and 5 nM), and the results revealed that IAA exposure significantly decreased the oocyte development competence. This research confirmed that the IAA-induced ferroptosis in oocytes was driven by glutathione peroxidase 4 (GPX4) by determining the expression levels of 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA), FerroOrange, GPX4, and solute carrier family 7 member 11 (SLC7A11). Melatonin, known for its ability to chelate iron and modulate iron metabolism and lipid peroxidation, was investigated for its potential to counteract IAA-induced ferroptosis in oocytes. The results showed that melatonin treatment alleviated the IAA-induced reduction in oocyte developmental competence, and significantly restored GPX4 expression. Furthermore, the levels of glutathione (GSH), glutathione disulfide (GSSG), and malondialdehyde (MDA) were measured, and it was found that melatonin effectively counteracted ferroptosis. Gene expression analysis further showed that the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) was significantly upregulated. Treatment with N-[4-[2,3-Dihydro-1-(2-methylbenzoyl)-1H-indol-5-yl]-5-methyl-2-thiazolyl]-1,3-benzodioxole-5-acetamide (ML385), a specific Nrf2 inhibitor, markedly attenuated the protective effects of melatonin. In conclusion, these findings suggest that IAA at environmentally relevant concentrations may induce ferroptosis in porcine oocytes under in vitro conditions, potentially compromising oocyte developmental competence. Furthermore, melatonin mitigates IAA-induced ferroptosis through activation of theNrf2 signaling pathway.