Thymoquinone enhances sperm DNA integrity in nicotineinduced infertile male rats

Abstract

Purpose: To assess the effects of thymoquinone (TQ) on the integrity of sperm DNA in nicotineinduced sperm impairment in rats. Methods: Adult male Sprague Dawley rats were randomized into four equal groups: Control group received normal saline orally for 60 days; nicotine group was subcutaneously injected with 5 mg/kg/day nicotine for 30 days and then given normal saline for the next 30 days; TQ group was given normal saline for 30 days followed by TQ at 5 mg/kg/day for 30 days; and nicotine-TQ group received 5 mg/kg of nicotine for 30 days and 5mg/kg of TQ for another 30 days. Sperm DNA breakages were evaluated using Comet assay. The expression levels of protamine 1 (PT1) and transition nuclear protein 2 (Tnp2) genes which are essential for the proper compaction of the sperm DNA were analyzed by quantitative polymerase chain reaction (qPCR). Results: Thymoquinone significantly decreased DNA fragmentation in the sperm of nicotine-treated rats. However, there was no change in PT1 gene expression. Tnp2 was downregulated in the nicotine group and slightly upregulated in nicotine-TQ group (p < 0.05). Conclusion: The results demonstrate the potential benefits of TQ in improving sperm DNA quality of nicotine-induced male infertility.