摘要目的 观察慢性氟中毒大鼠大脑及血清氧化应激水平改变及维生素E (Vitamin E,VE)的拮抗作用,探讨慢性氟中毒脑损伤机制.方法 健康纯系SD大鼠30只,按体质量采用随机数字表法分为3组,每组10只,雌雄各半.对照组自由饮用自来水,含氟量＜ 0.5 mg/L;染氟组饮水中加入氟化钠,含氟量为50.0 mg/L;染氟-VE拮抗组饮水含氟量为50.0 mg/L,同时给予VE 50.0 mg/kg灌胃,每天1次.各组大鼠均给予标准饲料,含氟量6.2 mg/kg.实验周期为10个月,处死大鼠,氟离子选择电极法测定骨氟含量;取脑组织和血清,黄嘌呤氧化酶法测定超氧化物歧化酶(SOD)活性、比色法测定谷胱甘肽过氧化物酶(GSH-Px)活性、硫代巴比妥酸荧光法测定丙二醛(MDA)含量以及比色法测定脑组织匀浆中羟自由基(OH-)、过氧化氢(H2O2)、超氧阴离子自由基(O-2)水平.结果 染氟组大鼠骨氟含量明显高于对照组[(211.07±48.52)比(33.40±9.26) mg/kg,P＜ 0.01].染氟组大鼠脑组织中SOD及GSH-Px活性[(20.10±1.98) kU/g、(28.70±19.35)kU/L]均低于对照组[(37.05±3.13)kU/g、(59.63±12.83)kU/L,P均＜0.01],而染氟-VE拮抗组SOD活性[(26.27±1.74)kU/g]高于染氟组(P＜0.01);染氟组大鼠血清SOD及GSH-Px活性[(11.55±1.75) kU/L、(79.50±19.18)U/L]均低于对照组[(20.79±2.43) kU/L、(170.00±14.68)U/L,P均＜0.01],而染氟-VE拮抗组SOD活性[(17.23±0.68)kU/L]高于染氟组(P＜0.01);染氟组大鼠脑组织及血清MDA含量[(8.84±0.69) μmol/L、(1.46±0.11) nmol/L]均高于对照组[(1.27±0.74) μmol/L、(0.83±0.10) nmol/L,P均＜0.01],而染氟-VE拮抗组MDA含量[(4.51±1.13)μmol/L、(1.29±0.02)nmol/L]均低于染氟组(P均＜0.01);染氟组大鼠脑组织中OH-、H2O2及O_水平[(24.24±1.80)kU/g、(15.28±2.97) mmol/L、(6.53±0.96)U/g]均明显高于对照组[(11.44±1.63)kU/g、(5.28±1.20)mmol/L、(2.93±0.42) U/g,P均＜0.01],而染氟-VE拮抗组OH-、H2O2及O-·2水平[(14.43±0.76)kU/g、(8.09±0.55)mmol/L、(4.41±0.49)U/g]均均低于染氟组(P均＜0.01).结论 慢性氟中毒大鼠脑组织及血清氧化应激水平升高,可能是脑损伤的主要机制之一;采用抗氧化剂(VE)可起到氟毒性氧化损伤的干预作用.

abstractsObjective To detect the levels of oxidative stress in brain and serum of rats with chronic fluorosis and the antagonistic effects of vitamin E (VitE),and to reveal the role of oxidative stress in brain injury.Methods Thirty healthy SD rats were divided into three groups based on body weight by means of a random number table (10 rats in each group,half male and half female).In the control group,the rats were fed with drinking water containing less than 0.5 mg/L fluoride;in the fluoride group,the rats were fed with high doses of sodium fluoride in drinking water (50.0 mg/L) and the VitE antagonistic group were fed with the same content of fluoride in drinking water as the fluoride group,but adding VitE (50.0 mg/kg) by intragastric administration once a day.All rats were fed with normal diet (6.2 mg/kg).After exposure to fluoride for 10 months,all rats were put to death,dental fluorosis of the rats was examined and the fluoride content in bone was determined by fluoride-ion selective electrode;the activity of superoxide dismutase (SOD) was determined by the xanthine oxidase method and glutathione peroxidase (GSH-Px) by the colorimetric method,the level of malonaldehyde (MDA) by the glucosinolates barbituric acid fluorescence method and the levels of OH-,H2O2 and O-·2 in rat serum and/or brain were detected by the colorimetric method.Results In the rats of the fluoride group,fluoride content in bone was higher as compared to control [bone fluoride:(211.07 ± 48.52) vs.(33.40 ± 9.26) mg/kg,P ＜ 0.01].The activities of SOD and GSH-Px in rat brains of the fluoride group [(20.10 ± 1.98) kU/g,(28.70 ± 19.35) kU/L] were significantly lower than those of controls [(37.05 ± 3.13) kU/g,(59.63 ± 12.83) kU/L,all P ＜ 0.01],the activity of SOD in VitE antagonistic group [(26.27 ± 1.74) kU/g] was higher than the fluoride group (P ＜ 0.01);the activities of SOD and GSH-Px in rat serum of the fluoride group were significantly decreased [(11.55 ± 1.75) kU/L,(79.50 ± 19.18) U/L] than those of controls [(20.79 ± 2.43) kU/L,(170.00 ± 14.68) U/L,all P ＜ 0.01],the activity of SOD in VitE antagonistic group [(17.23 ± 0.68) kU/L] was higher than the fluoride group (P ＜ 0.01).The levels of MDA in rat brain and serum of the fluoride group [(8.84 ± 0.69) μmol/L,(1.46 ± 0.11) nmol/L] were significantly higher than those of controls [(1.27 ± 0.74) μmol/L,(0.83 ± 0.10) nmol/L,all P＜ 0.01],VitE antagonistic groups [(4.51 ± 1.13) μmol/L,(1.29 ± 0.02) nmol/L] were lower than the fluoride groups (all P ＜ 0.01).The levels of OH-,H2O2 and O-·2 in rat brains of the fluoride group [(24.24 ± 1.80) kU/g,(15.28 ± 2.97) mmol/L,(6.53 ± 0.96) U/g] were significantly higher than those of controls [(11.44 ± 1.63) kU/g,(5.28 ± 1.20) mmol/L、,(2.93 ± 0.42) U/g,all P ＜ 0.01],VitE antagonistic groups [(14.43 ± 0.76) kU/g,(8.09 ± 0.55) mmol/L,(4.41 ± 0.49) U/g] were lower than the fluoride groups (all P ＜ 0.01).Conclusions Elevated levels of oxidative stress are found in brain and serum of the rats with chronic fluorosis,which may be a main mechanism of brain injury.VitE may play an important antagonistic role in oxidative damage induced by fluoride toxicity.