细胞外信号调节蛋白激酶5在慢性氟中毒大鼠大脑中的免疫组织改变

Correlation of immune tissue changes in brain of chronic fluorosis rats by extracellular signal regulating protein kinase 5

目的通过检测慢性氟中毒大鼠脑组织分裂原激活的蛋白激酶(MAPK)信号转导通路中细胞外调节蛋白激酶5(ERK5)在大脑不同功能分区中的表达与活性,研究慢性氟中毒脑损伤的相关机制。方法 30只SD大鼠按性别和体重随机分为3组,每组10只。对照组自由饮用自来水,含氟量低于0.5 mg/L;低氟组饮水含氟量10 mg/L;高氟组饮水含氟量50 mg/L。实验6个月,观察染氟大鼠氟斑牙情况;用氟离子电极法测量大鼠尿氟含量;通过HE染色观察大鼠皮质及海马区的变化;用免疫组化方法检测大鼠脑组织中皮质区、海马CA3区、海马CA4区中P-ERK5、ERK5的蛋白表达水平。结果染氟组大鼠出现不同程度的氟斑牙,尿氟含量增加(P<0.05);染氟组大鼠皮质及海马CA3区、CA4神经细胞排列稍紊乱,并有轻度的空泡变性(神经元水肿),高氟组更为严重;高氟组大鼠皮质区P-ERK5蛋白水平高于其他组(P<0.05),染氟组大鼠海马CA3区与正常组比较有统计学意义(P<0.05),海马CA4区各组间比较均有统计学意义(P<0.01);高氟组大鼠皮质区、海马CA3区、海马CA4区ERK5蛋白水平与其他组比较有统计学意义(P<0.05);另外ERK5的活化水平在海马CA4区有降低的趋势(P<0.05)。结论慢性氟中毒导致大鼠脑皮质区及海马CA3、CA4区P-ERK5、ERK5蛋白表达水平增加,可能与慢性氟中毒大鼠脑损伤免疫组织改变有一定关系。

Objective To study the mechanism of brain damage in chronic fluorosis, the expression and activity of extracellular regulated protein kinase 5 in different functional areas of brain were detected by detecting the mitogen activated protein kinase signal transduction pathway in the brain tissue of chronic fluorosis rats. Methods Thirty SD rats were randomly divided into 3 groups basing on gender and weight, 10 rats in each group. The rats in control group were fed with free drinking tap water containing less than 0.5-mg fluoride（ NaF ） /L , the rats in low fluoride group with lO-mg fluoride/L,the rat in high dose fluoride group with 50-mg fluoride/L. After 6 months of experiment, to observe the situation of dental fluorosis in rats exposed to fluoride, urine fluoride contents were tested by fluoride ion electrode method, the changes of cortex and hippocampus of rats were observed by HE staining, the expression and activity of extracellular P-ERKS,ERK5 protein in occipital area, hippocampus CA3 region and CA4 region of hippocampus were detected by immunohistochemical method. Results Fluoride group rats had dental fluorosis,urine fluoride increased （P〈0.05） ; The nerve cells in the cortex and hippocampus CA3 and CA4 area of rats exposed to fluoride were slightly disordered arrangement, and there was slight degeneration of the vacuoles （ neuronal edema） , which was more serious in the high fluoride group ; the levels of P-ERK5 protein in the high fluoride group in the Cortical area were statistically significant （P〈0.05） , in the hippocampal CA3 area, the fluoride group was significantly higher than that in the normal group （ P〈0.05 ） , among them, there were significant statistical significance among all the groups in the hippocampus CA4 region （ P〈0.05 ） ; the levels of ERK5 protein in fluoride exposed group were significantly higher than other groups in cortical area, hippocampal CA3 area and CA4 area of hippocampus （ P 〈 0.05 ） ; in addition, the ERK5 activation level of in hippocampus CA4region was decreased （ P〈0.05 ）. Conclusion The expression level of and P-ERK5 and ERK5 in hippocampus CA3, CA4 and in the cortex and of rats caused by chronic fluorosis was increased, which maybe correlated with damaged brain immune tissues caused by flnorosis.