This study evaluated the adverse effects of low-dose imidacloprid (IMI) on the characteristics of sperm from male Wistar rats. Thirty mature male rats were equally divided into three groups and orally administered vehicle (Control Group), acceptable daily intake (ADI) concentration of IMI (Group 1), and IMI at a dose 10-fold that of the ADI (Group 2) for 90 days. The findings revealed that IMI caused abnormalities in sperm concentrations and morphologies, accompanied by an imbalance of the gonadal hormone testosterone. Histopathological damage and decrease of testosterone levels were observed in testes from rats treated with IMI. However, estradiol and gonadotropin levels were unchanged after IMI treatment. IMI inhibited the activity of cytochrome P450 3A4 (CYP3A4) and left itself existed in the organism of rats. The indicators relating to sperms and CYP3A4 activity were recovered when rats were co-treated with IMI and CYP3A4 inducer rifampicin together. These results indicated that low-dose IMI exposure caused sperm abnormalities through affecting on the spermiogenesis in testis. Inhibition of CYP3A4 activity by IMI largely contributed to its sperm toxicity. Thus, IMI exposure at doses close to real-world settings resulted in sperm toxicity on rats, which might be a potential risk factor for human reproductive diseases.

本研究评估了低剂量吡虫啉 (IMI) 对雄性 Wistar 大鼠精子特征的不利影响。30 只成熟雄性大鼠等分为三组，口服给药载体（对照组）、每日可接受摄入量 (ADI) 的 IMI（组 1）和 10 倍 ADI 剂量的 IMI（组 2） 90 天。研究结果表明，IMI 会导致精子浓度和形态异常，并伴有性腺激素睾酮的失衡。在用 IMI 治疗的大鼠的睾丸中观察到组织病理学损伤和睾酮水平降低。然而，IMI 治疗后雌二醇和促性腺激素水平没有变化。IMI 抑制细胞色素 P450 3A4 (CYP3A4) 的活性并使其自身存在于大鼠体内。当大鼠与IMI和CYP3A4诱导剂利福平共同治疗时，与精子和CYP3A4活性相关的指标恢复。这些结果表明，低剂量IMI暴露通过影响睾丸中的精子发生而导致精子异常。IMI 对 CYP3A4 活性的抑制在很大程度上导致了其精子毒性。因此，在接近现实环境的剂量下暴露于 IMI 会导致对大鼠的精子毒性，这可能是人类生殖疾病的潜在风险因素。