雄黄中砷对大鼠新事物识别能力的影响

Effect of Arsenic in Realgar on Rat Ability in Novel Objects Recognition Test

目的:使用氢化物发生-冷阱捕集-原子吸收光谱法(HG-CT-AAS)测定大鼠大脑组织和血中无机砷(iAs),一甲基砷酸(MMA)和二甲基砷酸(DMA)的含量,研究雄黄对大鼠中枢神经系统的毒性影响。方法:将96只Wistar大鼠随机分为正常组,0.3,0.9,2.7 g·kg^(-1)雄黄组,分别连续灌胃14,28,42 d,正常组灌胃相同剂量的羧甲基纤维素钠(CMC-Na)水溶液,共12组,每组8只。采用HG-CT-AAS测定血和大脑组织中iAs,MMA和DMA的含量,新事物识别实验观察大鼠的新事物识别能力,透射电镜观察海马神经元超微结构的变化。结果:实验动物生长发育、体质量及海马系数变化各组之间均无差异。HG-CT-AAS测定大鼠大脑及血中各形态砷含量的方法线性、精密度、准确度与回收率良好;在雄黄组大鼠大脑中检测到MMA,DMA,且呈时间-剂量-效应关系;在雄黄组大鼠血中检测到iAs,MMA和DMA;大鼠海马神经元内核膜、线粒体及内质网等随着雄黄暴露剂量以及时间的增加,逐渐出现损伤;雄黄暴露14 d后,与正常组比较,各雄黄组新事物识别指数差异无统计学意义;暴露28 d后,仅2.7 g·kg^(-1)雄黄组与正常组比较有统计学意义(P<0.05);暴露42 d后,与正常组比较,0.9,2.7 g·kg^(-1)雄黄组大鼠的新事物识别指数明显降低(P<0.05)。结论:雄黄在大鼠体内的代谢产物为iAs,MMA,DMA。MMA和DMA可通过血脑屏障在脑组织中蓄积,引起新事物识别能力下降,造成海马神经元细胞损伤。

Objective: To determine the contents of inorganic arsenic(iAs),monomethylarsonic acid(MMA)and dimethylarsinic acid(DMA)in brain tissues and blood by using hydride generation-cold trapatomic absorptionspectrometry(HG-CT-AAS),and to explore the toxic effects of Realgar on central nervous system of rats. Method:The 96 Wistar rats were randomly divided into 4 groups:normal control group,0.3,0.9 and 2.7 g·kg^(-1) Realgar groups. They then received intragastric administration for 14,28 and 42 days respectively,so a total of 12 groups were formed,with 8 animals in each group. The normal group was given the same dose of sodium carboxymethyl cellulose(CMC-Na)by gavage. The contents of iAs,MMA and DMA in blood and brain tissues were determined by HG-CT-AAS. The novel object recognition test was conducted to observe the learning and memory ability of rats. The changes of hippocampal neuron ultrastructure were observed by transmission electron microscopy. Result: There was no difference in the growth,weight and hippocampal coefficient of the experimental animals. The method of HG-CT-AAS showed a good linearity,precision,accuracy and recovery in content determination of arsenic(at various forms)in rat brain and blood. MMA and DMA were detected in the brain of realgar groups at time-dose-effect relationship. iAs,MMA and DMA were detected in the blood of Realgar groups. The nuclear membrane,mitochondria and endoplasmic reticulum in hippocampus neurons of rats were gradually damaged with the increase of Rhubarb exposure dose and time. After 14 days of exposure to Realgar,compared with the normal control group,there was no significant difference in the novel object recognition index among Realgar groups. After 28 days of exposure,only 2.7 g·kg^(-1) Realgar group showed statistically significant difference with the control group(P<0.05). After 42 days of exposure,the novel object recognition index of 0.9 and 2.7 g·kg^(-1) Realgar groups was significantly lower than that in normal control group(P<0.05). Conclusion: The metabolites of Realgar in rats are iAs,MMA and DMA. MMA and DMA can be accumulated in the brain tissue through the blood-brain barrier,causing the decline of the ability of learning and memory and leading to damage of hippocampal neurons.