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目的观察17β-雌二醇(E2)暴露对雄性大鼠的生殖内分泌毒性,探讨其调控精子发生的机制。方法 E2经口灌胃染毒Wistar大鼠8周,剂量为1.00、0.50、0.10和0.01mg.kg-1.d-1,对照组为玉米油。观察一般状况,检测精子参数,利用放免方法检测血清激素T、E2、LH和FSH的水平,原子吸收法检测金属Zn和Ca水平,荧光定量PCR检测睾丸中类固醇急性调节蛋白(StAR)、细胞色素P450胆固醇侧链裂解酶(P450scc)和3β-羟基类固醇脱氢酶(3β-HSD)转录水平,免疫印迹检测雌激素受体(ERα和ERβ)和雄激素受体(AR)的蛋白水平。结果染毒8周后睾丸重量及系数显著减轻(P<0.01);血清T在各剂量组出现剂量相关的下降,E2出现剂量相关的增加,各剂量组差别均具有统计学意义(P<0.01)。LH和FSH也有不同程度降低。血清中Zn的水平降低,在0.50和1.00mg/kg剂量组差别具有统计学意义(P<0.01)。附睾尾精子计数明显减少,精子存活度下降。RT-PCR结果表明睾丸内StAR、P450scc mRNA水平下降。ERα蛋白表达显著增加,AR蛋白表达显著减少,差别均具有统计学意义(P<0.01)。结论青春期E2暴露可影响睾丸发育,包括睾酮合成和精子发生,其机制可能是循环雌激素的增加干扰下丘脑-垂体-性腺轴(HPGA)间接作用于睾丸间质细胞,还可能通过ERα途径直接抑制了睾酮合成酶。金属Zn可能参与了生殖毒性作用。
Objective To observe the reproductive and endocrine toxicity of 17β-estradiol (E2) exposure in male rats and to explore its mechanism of regulating spermatogenesis. Methods E2 Wistar rats were orally administered orally for 8 weeks at the doses of 1.00, 0.50, 0.10 and 0.01 mg.kg-1.d-1, while the control group was corn oil. Serum levels of T, E2, LH and FSH were measured by radioimmunoassay. Levels of metal Zn and Ca were detected by atomic absorption spectrometry. Apoptosis rates of steroid Acute Regulatory Protein (StAR), cytochromes P450 cholesterol side chain cleavage enzyme (P450scc) and 3β-hydroxysteroid dehydrogenase (3β-HSD) were detected by Western blot. The protein levels of estrogen receptor (ERα and ERβ) and androgen receptor (AR) Results The testicular weight and coefficient were significantly reduced after 8 weeks of exposure (P <0.01). Serum T showed a dose-related decrease in each dose group and a dose-related increase in E2 with statistical significance (P <0.01) ). LH and FSH are also reduced to varying degrees. The level of Zn in serum decreased, and there was a significant difference between the 0.50 and 1.00mg / kg dose groups (P <0.01). Epididymal sperm count was significantly reduced, decreased sperm viability. RT-PCR results showed that the level of StAR and P450scc mRNA in testis decreased. ERα protein expression increased significantly, AR protein expression was significantly reduced, the difference was statistically significant (P <0.01). Conclusion Adolescent E2 exposure may affect testicular development, including testosterone synthesis and spermatogenesis. The mechanism may be that the increase of circulating estrogen interferes with the hypothalamic-pituitary-gonadal axis (HPGA) indirectly on testicular stromal cells and may also be directly mediated by the ERα pathway Testosterone synthase is inhibited. Metal Zn may be involved in reproductive toxicity.