The possible protective role of zinc oxide nanoparticles (ZnONPs) on testicular and epididymal structure and sperm parameters in nicotine-treated adult rats (a histological and biochemical study).

Exposure to nicotine in smoking contributes to most unexplained male infertility but the mechanisms remain to be fully elucidated. Zinc (Zn) is an essential trace element in normal growth, development and reproduction. Zinc oxide nanoparticles (ZnONPs) are well-known antioxidants. Therefore, this work was designed to investigate the potential ability of ZnONPs to protect testis and epididymis in nicotine-treated rats. Forty adult male Wistar albino rats were divided into control group and two experimental groups (treated and supplemented rats). In the treated group, rats received nicotine at a dose of 1 mg/kg/day orally for 30 days. Rats in the supplemented group received ZnONPs (10 mg/kg/day) with nicotine (1 mg/kg/day), orally for the same period. Testicular and epididymal sections were stained with H&E to assess the histological changes. Negrosin-eosin staining of epididymal sperms was performed to assess their viability and morphological changes. Serum testosterone, FSH and LH levels were assessed. Also, oxidative stress parameters and semiquantitative real-time PCR for steroidogenic enzymes were measured. Morphometric studies of both organs were statistically analyzed. Mild to severe testicular and epididymal structural changes together with sperm morphological abnormalities were detected in nicotine-treated rats. Biochemical results also showed a decrease in all measured parameters except for an increased malondialdehyde (MDA) level that meant deterioration of their reproductive function. On the other hand, ZnONP supplementation in the last group showed an obvious improvement in all investigated parameters.