Zearalenone Exposure Disrupts Blood-Testis Barrier Integrity through Excessive Ca²⁺-Mediated Autophagy

Zearalenone (ZEA), a common mycotoxin in grains and animal feeds, has been associated with male reproductive disorders. However, the potential toxicity mechanism of ZEA is not fully understood. In this study, in vivo and in vitro models were used to explore the effects of ZEA on the blood-testis barrier (BTB) and related molecular mechanisms. First, male BALB/C mice were administered ZEA orally (40 mg/kg·bw) for 5-7 d. Sperm motility, testicular morphology, and expressions of BTB junction proteins and autophagy-related proteins were evaluated. In addition, TM4 cells (mouse Sertoli cells line) were used to delineate the molecular mechanisms that mediate the effects of ZEA on BTB. Our results demonstrated that ZEA exposure induced severe testicular damage in histomorphology and an ultrastructural, time-dependent decrease in the expression of blood-testis barrier junction-related proteins, accompanied by an increase in the expression of autophagy-related proteins. Additionally, similar to the in vitro results, the dose-dependent treatment of ZEA increased the level of cytoplasmic Ca²⁺ and the levels of the autophagy markers LC3-II and p62, in conjunction with a decrease in the BTB junction proteins occludin, claudin-11, and Cx43, with the dislocation of the gap junction protein Cx43. Meanwhile, inhibition of autophagy by CQ and 3-MA or inhibition of cytoplasmic Ca²⁺ by BAPTA-AM was sufficient to reduce the effects of ZEA on the TM4 cell BTB. To summarize, this study emphasizes the role of Ca²⁺-mediated autophagy in ZEA-induced BTB destruction, which deepens our understanding of the molecular mechanism of ZEA-induced male reproductive disorders.