慢性氟中毒大鼠大脑皮质P-糖蛋白和细胞核因子-κB改变

摘要

目的 研究慢性氟中毒大鼠大脑皮质中p-糖蛋白(P-glycoprotein,P-gp)和细胞核因子κB(Nuclear factor κB,NF-κB)的表达变化,探讨氟中毒神经系统损害的发病机制.方法 60只SD大鼠按体质量随机分为3组,即:对照组、小剂量染氟组、大剂量染氟组,饮水含氟(NaF)量分别为＜0.5、10.0、50.0 mg/L.实验期为6个月.采用免疫组织化学方法、蛋白印迹方法和实时荧光定量PCR方法检测P-gp的蛋白和mRNA表达水平,用蛋白印迹方法检测NF-κB的蛋白表达水平.结果 小剂量染氟组、大剂量染氟组大鼠大脑皮质P-gp细胞阳性表达数(48.46±8.00、53.72±9.15)和蛋白表达水平[(189.47±3.14)％、(191.36±11.09)％]均高于对照组[28.21±6.13、(100.00±3.86)％,P均＜0.05]；小剂量染氟组、大剂量染氟组NF-κB蛋白表达水平[(365.97±6.04)％、(417.15±10.89)％]均明显高于对照组[(100.00±10.07)％,P均＜0.05]；小剂量染氟组、大剂量染氟组大鼠大脑皮质中P-gp mRNA表达(2396±427、3479±371)均高于对照组(260±106,P均＜0.05).结论 慢性氟中毒引起大鼠大脑皮质中P-gp和NF-κB表达明显升高,这些改变可能与氟中毒性脑损伤发生机制有一定的关系.%Objective The aim of the study was to investigate the expression of P-glycoprotein (P-gp)and nuclear factor κB (NF-κB) in the cerebral cortex of rat with chronic fluorosis,and to reveal the mechanisms of damaged nervous system resulted from the toxicity of fluoride.Methods Sixty SD rats were randomly divided into three groups.The rats in each group were given drinking water containing different levels of fluoride:control group less than 0.5 mg/L,small amount of fluoride exposure group 10.0 mg/L and large amount of fluoride exposure group 50.0 mg/L.The animals were examined at the sixth month after initiating the experiment.Protein levels of P-gp and NF-κB in brain tissues were detected by immunocytochemistry and Western blotting,and the P-gp protein and mRNA level by quantitative real time PCR method.Results As compared to the control group(28.21 ±6.13),the numbers of positive staining cells by P-gp antibody in the cortex of rat brains were significantly increased in both the small and the large amount of fluoride exposure groups[(48.46 ± 8.00),(53.72 ± 9.15),respectively,all P ＜ 0.05] ; the protein levels in the control group(100.00 ± 3.86)％ detected by Western blotting were significantly increased in the cortex of rat brains treated with fluoride in both the small and the large amount of fluoride exposure groups[(189.47 ± 3.14)％,(191.36 ± 11.09)％,respectively,all P ＜ 0.05].The significantly increased expression of NF-κB at the protein level was observed in the cortex of rat brains of the small and the large amount of fluoride exposure groups[(365.97 ± 6.04)％ and (417.15 ± 10.89)％,respectively] as compared with the control group[(100.00 ± 10.07)％,all P ＜ 0.05].The mRMA level of P-gp in the cortex of rat brains of the small and the large amount of fluoride exposure groups(2396 ± 427,3479 ± 371,respectively) were higher than that of the control group(260 ± 106,all P ＜ 0.05).Conclusion The increased expressions of P-gp and NF-κB in the cortex of rat brains are induced by chronic fluorosis,which might be connected with the mechanism of brain damages.