长期接触低剂量氯化甲基汞致脑发育损伤大鼠动物实验模型的研究

目的:观察大鼠长期接触低剂量氯化甲基汞(MMC)不同发育阶段仔鼠脑汞含量。方法:雌性Wistar大鼠体重(120±20)g,随机分为3个实验组和对照组各30只。实验组母鼠从妊娠前90天至仔鼠出生后30天连续喂饲含有不同剂量(0.75、1.50和3.00 mg/kg)MMC的普通饲料,对照组给予普通饲料。采用干烧法用F732-V冷原子吸收测汞仪分别测定仔鼠大脑、小脑和海马组织汞含量。结果:在建立MMC所致脑发育损伤动物实验模型过程中,发现实验组母鼠的产子率低于正常鼠,高剂量组尤为明显,生后仔鼠外观无异常表现,不同脑区(大脑、小脑和海马)脑汞含量差异无统计学意义(P>0.05)。各实验组生后不同时间仔鼠脑汞含量明显高于相应对照组(P<0.05),各实验组仔鼠脑汞含量随母鼠接触剂量的增高而有不同程度升高(P<0.05),同一实验组内仔鼠脑汞含量随生后时间的延长逐渐升高,在生后30天达峰值。结论:甲基汞可透过血脑屏障蓄积于仔鼠脑内,且仔鼠脑汞含量与母鼠接触剂量之间存在一定剂量反应关系。

Research on brain damage of rat models caused by long-term exposure to low doses of methylmercury chloride

Objective:To observe the rat offspring's brain mercury content at different developmental stages after long-term exposure to low doses of methylmercury chloride(MMC).Methods:120 female Wistar rats(120±20)g were randomly assigned to the experimental groups,fed with common fodder containing various amounts of MMC(0.75,1.50 and 3.00 mg/kg) for 90 days before gestation to 30 d post parturition and one control group without MMC.Dry method was used with F732-V Automated Mercury Analyzer to measure the pups' mercury content in cerebrum,cerebellum and hippocampus.Results:The number and weight of pups of ExpⅠwere nearly the same with that of control group,however which were lower in ExpⅡand ExpⅢ,pups of different experimental group were normal in the appearance,there were no differences in MMC concentration among three brain regions(cerebra,cerebellum and hippocampus) within groups(P>0.05).The concentrations of Hg2+ in pups' brain of experimental groups at various postnatal days were markedly higher than those of the control group(P<0.05).Time-course studies in experimental group showed the concentrations of Hg2+ in pups' brain increased gradually during development and reached its peak at PND30.Conclusion:MMC could pass blood-brain barrier and accumulate in pups' brain.The enhanced effect is dose-dependent.