摘要
目的研究慢性氟中毒大鼠脑组织中细胞外信号调节蛋白激酶(Extracellular signal regulated kinases,Ras-Erk1/2)通路主要激酶表达变化及其对转录因子环一磷酸腺苷反应单元结合蛋白(cAMP Responsive Element Binding Protein,CREB)的影响。方法 SD(Sprague dawley)大鼠随机分为3组,即正常组、饮水中小剂量加氟(5 mg/L)组、大剂量加氟(50 mg/L)组,实验期为6个月。实验结束时,用氟离子选择电极法测定大鼠尿氟及血氟含量,尼氏染色检查神经细胞尼氏小体改变,蛋白印迹(Western-blotting)方法检测脑组织中小鸟苷三磷酸结合蛋白(small GTP-binding protein,Ras)、Erk1/2、CREB信号转导激酶的蛋白表达水平,实时荧光定量聚合酶链式反应(Real-time Polymerase Chain Reaction,Re-al-time PCR)方法检测c-fos基因mRNA表达水平。结果与对照组相比,染氟组大鼠有不同程度的氟斑牙及血氟尿氟升高;大脑皮质和海马部位神经细胞尼氏小体减少;脑组织中Ras、phospho-Erk1/2t、otal-Erk1/2及phospho-CREB蛋白表达水平上升(F值分别为19.9、114.59、4.6 9、7.6,P<0.05),以大剂量染氟组尤为明显t,otal-CREB在各组间未见明显改变;大剂量染氟组c-fos基因mRNA表达明显升高,而小剂量染氟组该基因mRNA表达降低。结论过多的氟可引起大鼠脑组织神经细胞损伤,脑组织中Ras-Erk1/2信号激酶通路过度激活可刺激转录因子CREB磷酸化,从而影响c-fos基因的表达,该过程可能参与慢性氟中毒脑损伤机制。
Objective To investigate the changes of Ras-Erk1/2 pathway in rat brains with chronic fluorosis and its influence on CREB.Methods The rats were randomly divided into 3 groups,i.e.,control group fed with drinking water containing less than 0.5 mg/L of fluoride;small amount of fluoride exposure group with drinking water containing 5 mg/L of fluoride;large amount of fluoride exposure group with drinking water containing 50 mg/L of fluoride.The animals were examined at six months after initiating the experiment.Fluoride contents in urine and blood were measured by fluoride-ion selective electrode method.Nissl bodies in neurons of brain sections were examined by Nissl staining technique.The protein levels of Ras,phospho-and total-Erk1/2,and phospho-and total-CREB were detected by Western blotting.The expression of c-fos mRNA was detected by Real-time PCR.Results As compared to controls,dental fluorosis,higher content of fluoride in urine and blood were found in the rats fed with excessive amount of fluoride in drinking water;changed numbers of Nissl body in neurons of the cortex and hippocampus were observed;the protein expressions of Ras,phospho-Erk1/2,total-Erk1/2 and phospho-CREB in the brains of rats with fluorosis were higher than those of controls（F：19.9,114.5,94.6,97.6,P0.05）,whereas no change of total-CREB was found between the rats with fluorosis and controls.The expression of c-fos mRNA was significantly increased in large amount of fluoride exposure group（F：166.63,P0.05）,and while decreased in small amount group as compared to controls.Conclusions Excessive fluoride exposure induced damage of neurons,activated Ras-Erk1/2 pathway,and stimulated high-phosphorylation of transcription factor CREB and therefore influenced the expression of c-fos,which might be connected to the mechanism of brain damage induced by chronic fluorosis.
出处
《中国地方病防治》
2011年第2期88-92,共5页
Chinese Journal of Control of Endemic Diseases
基金
科技部国际合作项目(编号:0102010DFB30530)
国家自然科学基金(编号:30760224)
贵州省优秀科技教育人才省长专项资金项目(编号:黔省专合字(2009)80号)
高层次人才特助项目(编号:TZJF-2008年-53号)
