Melatonin ameliorates testicular damages induced by nicotine in mice.

Objectives: Nicotine as a toxic substance leads to impairment of the reproductive system function. The aim of this study was to evaluate effects of melatonin on testicular alterations, sperm nuclear integrity, and epididymal sperm parameters in mice treated with nicotine.

Materials and Methods: Male mice were divided into four groups. Group A received the vehicle, group B received nicotine 0.1 mg/100 g BW, group C received melatonin 10 mg/kg, group D received nicotine plus melatonin. Evaluations were made by histology and Johnson's score for study of spermatogenesis, immunostaining for study of male germ cells apoptosis, sperm chromatin dispersion (SCD) test for assaying sperm chromatin integrity, enzyme-linked immunosorbent assay (ELISA) for assessment of serum levels of testosterone and luteinizing hormone (LH), and sperm parameters including morphology, motility, and count.

Results: Nicotine caused a significant decrease in spermatogenesis quantity and Johnson's score, sperm parameters, and sex hormones. Melatonin in group D, increased sperm chromatin integrity, improved spermatogenesis, Johnson's score, and sperm parameters ( P <.01) and reduced apoptosis ( P <0.01) in comparison with the nicotine group. Melatonin significantly increased testosterone and halo sperms. However, its effect on the LH level was insignificant. The serum testosterone and LH levels were negatively correlated with the DNA fragmentation index (DFI) (r= -0.86, P <0.001) and (r= -0.78, P <0.001), respectively.

Conclusion: this study showed administration of melatonin in nicotine-treated mice increases both quality and quantity of spermatogenesis and integrity of sperm's chromatin through reducing apoptosis and modifying the testosterone level.