不同时间点锰暴露对大鼠睾丸激素的影响研究

目的 探讨不同时间点锰暴露对大鼠睾丸睾酮、雌二醇、促卵泡激素和促黄体生成素的影响。方法 选取健康成年雄性SD大鼠共96只，在本实验条件适应性喂养7 d后，根据预先设计的授时时间点（ZT2、ZT8、ZT14与ZT20）随机分为对照组与锰暴露组，每组12只。锰暴露组的剂量为30 mg/kg MnCl2，对照组为等容量的蒸馏水，采取腹腔注射的染毒方式，分别于各授时时间点进行染毒，每天1次，持续21 d。d22于相同的授时时间点处死动物，获取动物睾丸，检测其睾酮（T）、雌二醇（E2）、促卵泡激素（FSH）和促黄体生成素（LH）含量。结果 锰暴露可引起睾丸激素的改变，但在不同的授时时间点，其睾丸T、E2、FSH、LH含量的改变不相一致。ZT2暴露时间点，FSH和LH降低，而T升高；ZT8暴露时间点，FSH降低，而E2和T升高；ZT14暴露时间点，所有观察指标变化差异无统计学意义；ZT20暴露时间点，FSH和LH降低，而E2和T升高。结论 锰暴露所致的雄性生殖功能损伤具暴露时间差异性，在锰的生殖毒性评价时可能需考虑其暴露时间。

Chronotoxicology of manganese-induced effects on testicular reproductive hormones

Objective The aim of this study was to explore the chronotoxicity of the exposure of manganese（Mn） on reproductive hormones of testis in male rats. Methods Ninety-six healthy male SPF SD rats were accustomed in 12h: 12h light-dark photoperiod for one week and then were divided into four Mn-exposure groups and four control groups. Mn-exposure groups were intraperitoneally injected (i.p.) with Mn (30mg/kg MnCl2·4H2O) and the control groups were administered with equal volume of water, respectively at zeitgeber time of ZT2， ZT8， ZT14 and ZT20 for continuous 21 days. The luteinizing hormone(LH), follicle-stimulating hormone(FSH), estradiol(E2) and testosterone(T) level of testis was measured by immunochemiluminometric assays(ICMAS) method and statistically analyzed by Cosinor analysis. Results Compared with the corresponding control groups, Mn-exposure groups showed change in the LH, FSH, E2 and T levels, but the results were different at different exposure time. At zeitgeber time of ZT2, the levels of FSH and LH decreased, and the level of T elevated. At zeitgeber time of ZT8, the level of FSH decreased, and the levels of T and E2 elevated. At zeitgeber time of ZT20, the levels of FSH and LH decreased, and the levels of T and E2 elevated. However, at zeitgeber time of ZT14, there was no significant change of our observation index. Conclusion The Mn-exposed male reproduction disorder had chronotoxicity. The exposure time may be considered when evaluating the male reproductive toxicity of manganese.