ORIGINAL ABSTRACT

Glyphosate is the most widely used herbicide in the world. In recent years, many studies have demonstrated that exposure to glyphosate-based herbicides (GHBs) was related to the decrease of serum testosterone and the decline in semen quality. However, the molecular mechanism of glyphosate-induced testosterone synthesis disorders is still unclear. In the present study, the effects of glyphosate on testosterone secretion and the role of endoplasmic reticulum (ER) stress in the process were investigated in TM3 cells. The effects of glyphosate at different concentrations on the viability of TM3 cells were detected by CCK8 method. The effect of glyphosate exposure on testosterone secretion was determined by enzyme-linked immunosorbent assay (ELISA). The expression levels of testosterone synthases and ER stress-related proteins were detected by Western blot and Immunofluorescence stain. Results showed that exposure to glyphosate at concentrations below 200 mg/L had no effect on cell viability, while the glyphosate above 0.5 mg/L could inhibit the testosterone secretion in TM3 cells. Treatment TM3 cells with glyphosate at 5 mg/L not only reduced the protein levels of testosterone synthase StAR and CYP17A1, inhibited testosterone secretion, but also increased the protein level of ER stress molecule Bip and promoted the phosphorylation of PERK and eIF2α. Pretreatment cells with PBA, an inhibitor of ER stress, alleviated glyphosate-induced increase in Bip, p-PERK and p-eIF2α protein levels, meanwhile rescuing glyphosate-induced testosterone synthesis disorders. When pretreatment with GSK2606414, a PERK inhibitor, the glyphosate-induced phosphorylation of PERK and eIF2α was blocked, and the glyphosate-inhibited testosterone synthesis and secretion was also restored. Overall, our findings suggest that glyphosate can interfere with the expression of StAR and CYP17A1 and inhibit testosterone synthesis and secretion via ER stress-mediated the activation of PERK/eIF2α signaling pathway in Leydig cells.