牛磺酸对甲基汞致大鼠脑皮质氧化损伤及谷氨酸代谢障碍的影响

Effects of taurine on oxidative damage of cerebral cortex and glutamate metabolism in rats induced by methyl mercury

目的探讨牛磺酸对甲基汞致大鼠脑皮质氧化损伤及谷氨酸代谢障碍的影响。方法选择SPF级健康SD大鼠48只,按照体质量随机分为对照组、低汞组、高汞组和牛磺酸组,每组12只。对照组腹腔注射生理盐水5 ml/kg,低汞和高汞组分别腹腔注射氯化甲基汞4和12μmol/kg,牛磺酸组在高汞组基础上皮下注射牛磺酸5 ml/kg,1次/d,每周注射5 d,连续4周。最后1次染毒后24 h,检测大鼠脑皮层中Hg含量、超氧化物歧化酶(SOD)、丙二醛(MDA)、谷胱甘肽(GSH)、谷胱甘肽过氧化物酶(GSH-Px)、谷氨酸(Glu)、谷氨酰胺(Gln)水平及谷氨酰胺酶(PAG)、谷氨酰胺合成酶(GS)活力。免疫组化检测海马组织中B淋巴细胞瘤-2 (Bcl-2)、半胱氨酸蛋白酶-3 (Caspase-3)表达。结果与对照组比较,随着染汞量增加,SOD、GSH、GSH-Px及Gln水平降低,MDA及Glu水平升高,PAG活力升高,GS活力降低,差异有统计学意义(P <0.05)。与高汞组比较,牛磺酸组SOD、GSH、GSH-Px及Gln水平明显升高,MDA及Glu水平明显降低,PAG活力明显降低,GS活力明显升高,差异有统计学意义(P <0.05)。与对照组比较,随着染汞量增加,脑皮质中Hg含量升高,海马Bcl-2表达减少,Caspase-3表达增多,差异有统计学意义(P <0.05)。与高汞组比较,牛磺酸组海马Bcl-2表达明显增多,Caspase-3表达明显减少,差异有统计学意义(P <0.05)。结论甲基汞诱导脑皮质氧化损伤及谷氨酸代谢障碍,牛磺酸对甲基汞造成的神经毒性具有一定的防护作用。

Objective To investigate the effects of taurine on cerebral cortex oxidative damage and glutamate metabolic disorder induced by methyl mercury in rats. Methods a total of 48 spf-grade healthy SD rats were selected and randomly divided into control group, low-mercury group, high-mercury group and taurine group according to body mass, with 12 rats in each group. In the control group, 5 ml/kg of normal saline was injected into the abdomen, and methylmercury chloride was injected into the abdomen of the low-mercury group at 4 μmol/kg. In the high-mercury group, methylmercury chloride was injected into the abdomen at 12 μmol/kg. Last one canister to 24 h after, detection of mercury（Hg） content in the rat cortex,superoxide dismutase（SOD）, malondialdehyde（MDA） and glutathione（GSH）, glutathione peroxidase（GSH-Px） and glutamate（Glu） and glutamine（Gln） levels and glutaminase（PAG）, glutamine synthetase（GS） activity. Immunohistochemistry was used to detect the expression of B lymphocytoma-2（bcl-2） and cysteine protease-3（caspase-3） in hippocampal tissues. Results ompared with the control group, with the increase of mercury exposure, SOD, GSH, GSH-Px and Gln levels decreased, MDA and Glu levels increased, PAG activity 2 increased, GS activity decreased, and the difference was statistically significant（P 0.05）. Compared with the high-mercury group, SOD, GSH, GSH-Px and Gln levels in taurine group were significantly increased, MDA and Glu levels were significantly decreased, PAG activity was significantly decreased, GS activity was significantly increased, and the difference was statistically significant（P〈0.05）. Compared with the control group, as the amount of mercury exposure increased, the content of Hg in cerebral cortex increased, the expression of hippocampal bcl-2 decreased,and the expression of caspase-3 increased, and the difference was statistically significant（P〈0.05）. Compared with the highmercury group, the expression of hippocampal bcl-2 and caspase-3 was significantly increased in taurine group, and the difference was statistically significant（P〈0.05）. Conclusions taurine has certain protective effects on the neurotoxicity of methyl mercury, which induces oxidative damage of cerebral cortex and glutamate metabolism disorder.