Beta-cypermethrin impairs reproductive function in male mice by inducing oxidative stress.

Cypermethrin (CYP), an insecticide, has deleterious effects on male reproductive function. The objective was to identify whether the effects of beta-CYP on male reproductive organs were associated with oxidative stress. Three doses of beta-CYP (1, 10, and 20mg/kg) were administered to male mice for 35 d, with or without vitamin E (20mg/kg). The moderate (10mg/kg) and high (20mg/kg) doses of beta-CYP not only decreased body weight and the weight of the testes, epididymides, seminal vesicles, and prostate (P<0.05) but also reduced serum testosterone concentration and the expression of steroidogenic acute regulatory protein (P<0.05), in addition to damaging the seminiferous tubules and sperm development. Furthermore, moderate and high doses of beta-CYP administration decreased sperm number, sperm motility, and intact acrosome rate (P<0.05). Based on ultrastructural analyses, high doses of beta-CYP produced swelling and degeneration of mitochondria and the smooth endoplasmic reticulum of Leydig cells and caused the formation of concentric circles. These toxic effects of beta-CYP may be mediated by increasing oxidative stress, as the moderate and high doses of this compound increased malondialdehyde and nitric oxide in testes (P<0.05); reduced the activity of catalase, glutathione peroxidase (GSH-Px), and superoxide dismutase (P<0.05); and activated ERK1/2 (P<0.05). Vitamin E reversed the effects of beta-CYP on testosterone production and testis damage (P<0.05 vs. the high-dose group). Therefore, we inferred that beta-CYP damaged the structure of testes and decreased sperm output by inducing oxidative stress.