Autophagy and apoptosis mediated nano-copper-induced testicular damage

Nano-copper has been increasingly employed in various products. In previous studies, we showed that nano-copper caused damage in the rat testis, but it remains unclear whether the toxic reaction can affect the reproductive function. In this study, following 28 d of exposure to nano-copper at a dose of 44, 88, and 175 mg/kg/day, there was a decrease in sperm quality, fructose content, and the secretion of sex hormones. Nano-copper also increased the level of oxidative stress, sperm malformation rate, and induced abnormal structural changes in testicular tissue. Moreover, Nano-copper upregulated the expression of apoptosis-related protein Bax and autophagy-related protein Beclin, and downregulated the expression of Bcl2 and p62. Furthermore, nano-copper (175 mg/kg) downregulated the protein expression of AMPK, p-AKT, mTOR, p-mTOR, p-4E-BP1, p70S6K, and p-p70S6K, and upregulated the protein expression of p-AMPK. Therefore, nano-copper induced damage in testicular tissues and spermatogenesis is highly related to cell apoptosis and autophagy by regulating the Akt/mTOR signaling pathway. In summary, excess exposure to nano-copper may induce testicular apoptosis and autophagy through AKT/mTOR signaling pathways, and damage the reproductive system in adult males, which is associated with oxidative stress in the testes.