Effects of methylmercury chloride on the brain chromatin structure in rats at various developing stages

妊娠７～１１ｄ的孕鼠，经腹腔连续注入氯化甲基汞（２ｍｇ／ｋｇ体重），采用Ｈｅｗｉｓｈ和Ｂｕｒｇｏｙｎｅ法分离纯化不同发育阶段新生大鼠的脑细胞核，来探讨氯化甲基汞对其脑染色质结构的影响。接触或不接触氯化甲基汞的大鼠脑细胞核分别经ＤＮａｓｅ１和ＥｃｏＲ１核酸内切酶消化后进行缺口翻译。结果接触氯化甲基汞生后３ｄ的大鼠脑细胞核３Ｈ－ｄＡＭＰ的掺入量明显低于相应未接触氯化甲基汞的对照组（Ｐ＜０．０５）。我们认为氯化甲基汞对大鼠发育过程中脑染色质结构的影响可能与胎、幼鼠对甲基汞神经毒性的易感有密切关系。

Effects of methylmercury chloride on the brain chromatin structure in rats at various developing stages

pregnant rats were injected peritoneally with methylmercury chloride of dosage of 2 mg/kg sequently from 7th llth day after gestation (organogenetic period). Brain nuclei of natal rats at various developing stages were separated and purified with Hewish Burgoyne method. The effects of methymlmercury chloride on brain chromatin structure of natal rats in different developing period were studied. Brain nuclei of rats exposed or unexposed to methylmercury chloride were digested by DNase 1 or EcoR 1,and then nick translation was performed.The amount of 3H dAMP incorporation into the nuclei of rats from exposed group of 3 day old was significantly lower than that of the unexposed group of 3 day old ( P <0 05).We believed that the effects of methylmercury chloride on chromatin structure of the brain nuclei at different developing stages might be closely related to sensitivity of the fetal and infant rats to neurotoxicity of methylmercury chloride.