Effects of chronic CuNPs treatment followed by termination for two spermatogenic cycles in the testicular functions of mice

The present study investigated the possible effects of copper nanoparticles (CuNPs) after discontinuing treatment on testicular activity in a mouse model. The male mice were given continuous CuNPs treatment for 70 days and left untreated for 70 days. The results show that even after the discontinuation of CuNPs treatment, the testicular impairment was persistent till 140 days at a higher dose (200 mg/kg group). The spermatogenesis, sperm parameters, proliferation and antioxidant status were suppressed in the higher dose groups. However, these effects were also observed at moderate levels in the other CuNPs treated groups, such as at 10 mg/kg and 100 mg/kg. The apoptosis was stimulated at a higher dose compared to the other groups. The testosterone, LH levels and AR expression were suppressed in all the CuNPs treated groups, along with slight elevation in the estrogen levels and up-regulated ERβ expression. The fertility data also showed a decline in all CuNPs treated groups with the lowest litter size in the 200 mg/kg treated group. Despite testis, epididymis and accessory sex organs like prostate, seminal vesicle, and vas deferens, histoarchitecture also showed impairment. This is the first report on how CuNPs affect the male reproductive system in mice even after treatment was terminated. The current study also demonstrated possible negative effects on male reproductive function that might last for longer at higher dosages of chronic CuNPs exposure even after termination.