Glyphosate decreases bovine oocyte quality by inducing oxidative stress and apoptosis

Glyphosate is a universal herbicide with genital toxicity, but the effect of glyphosate on oocytes has not been reported. This study aimed to evaluate the effect of glyphosate (0, 10, 20, 50 and 100 mM) on bovine oocyte in vitro maturation. We showed that 50 mM glyphosate adversely affects the development of bovine oocytes. Exposure of oocytes to 50 mM glyphosate caused an abnormal reduction in oxidative (redox) levels compared with that in the control group, with a significantly higher reactive oxide species level (P < 0.05) and significantly lower glutathione (GSH) expression (P < 0.05). Additionally, the mRNA levels of antioxidant genes (SOD1, SOD2, SIRT2, SIRT3) and the mitochondrial membrane potential (MMP) were significantly reduced (P < 0.05). Furthermore, treatment with 50 mM glyphosate-induced apoptosis, and the mRNA levels of the apoptotic genes Caspase-3 and Caspase-4 were significantly higher than those in the control group (P < 0.05); however, the mRNA level of BAX was significantly higher than that in the control group (P < 0.01). Additionally, the mRNA levels of the anti-apoptotic genes Survivin and BCL-XL were significantly lower than those in the control group (P < 0.05), and oocyte quality was adversely affected. Together, our results confirmed that glyphosate impairs the quality of oocytes by promoting abnormal oocyte redox levels and apoptosis.