叶酸对铅诱导的大鼠肺脏中氧化应激相关蛋白和内质网应激相关蛋白表达的影响

Effects of Folic Acid on Expression of Oxidative Stress-Related Proteins and Endoplasmic Reticulum Stress-Related Proteins in Lead-Induced Lung of Rats

本试验旨在研究叶酸对铅诱导的大鼠肺脏中氧化应激相关蛋白核因子E2相关因子2(Nrf2)、血红素氧合酶-1(HO-1)与内质网应激相关蛋白C/EBP同源蛋白(CHOP)、葡萄糖调节蛋白78(GRP78)表达的影响,探讨叶酸对铅暴露导致的肺脏损伤的干预作用。将32只成年无特定病原体(SPF)级雄性SD大鼠按体重一致原则平均分成4组(n=8):对照组(C组,自由饮水+1 mL去离子水灌胃)、染铅组(L组,自由饮0.2%的醋酸铅溶液+1 mL去离子水灌胃)、干预组(I组,自由饮0.2%的醋酸铅溶液+1 mL叶酸悬浊液灌胃)、叶酸组(F组,自由饮水+1 mL叶酸悬浊液灌胃)。叶酸悬浊液按照0.4 mg/kg BW的灌胃剂量配制,各组大鼠每天灌胃1次,连续灌胃14 d后取肺脏组织,用免疫荧光法测定Nrf2、HO-1、CHOP、GRP78这4种蛋白的表达水平。结果表明:与C组相比,L组、I组和F组的初体重、末体重、日增重、净增重、肺脏指数无显著变化(P>0.05);L组、I组和F组肺脏中CHOP和GRP78蛋白的表达水平显著升高(P<0.05);L组和I组肺脏中HO-1蛋白的表达水平显著升高(P<0.05),Nrf2蛋白表达水平无显著变化(P>0.05);F组肺脏中HO-1蛋白的表达水平显著降低(P<0.05),Nrf2蛋白表达水平无显著变化(P>0.05)。与L组相比,I组和F组的初体重、末体重、日增重、净增重、肺脏指数差异不显著(P>0.05);I组、F组肺脏中HO-1和CHOP蛋白的表达水平显著降低(P<0.05),Nrf2和GRP78蛋白的表达水平均无显著变化(P>0.05)。由以上结果可知:1)铅暴露使大鼠肺脏中HO-1、CHOP蛋白的表达水平升高,而叶酸干预后降低了HO-1、CHOP蛋白的表达水平;2)铅暴露引起的大鼠肺脏氧化应激、内质网应激分别与Nrf2/HO-1、GRP78/CHOP通路密切相关,叶酸对HO-1、CHOP蛋白的表达有直接影响;3)0.4 mg/kg BW的叶酸对0.2%醋酸铅暴露引起的氧化应激和内质网应激而造成的大鼠肺脏损伤具有一定的拮抗作用。

The purpose of this experiment was to study the effects of folic acid on the expression of oxidative stress-related proteins nuclear factor erythroid 2-related factor 2(Nrf2)and heme oxygenase-1(HO-1)and endoplasmic reticulum stress-related proteins C/EBP homologous protein(CHOP)and glucose-regulated protein 78(GRP78)in lead-induced lung of rats,and to explore the intervention effect of folic acid on lung tissue damage caused by lead exposure.Thirty-two specific pathogen free(SPF)-grade adult SD rats(male)were averagely divided into 4 groups(n=8)according to body weight:control group(group C,free drinking water+1 mL deionized water gavage),lead group(group L,free drinking 0.2%lead acetate solution+1 mL deionized water gavage),intervention group(group I,free drinking 0.2%lead acetate solution+1 mL folic acid suspension gavage),and folic acid group F(group F,free drinking water+1 mL folic acid suspension gavage).The folic acid suspension was prepared according to the dose of 0.4 mg/kg BW folic acid.Rats in each group were given intragastric administration once a day.After 14 days,the lung tissue was sampled and the expression levels of Nrf2,HO-1,CHOP and GRP78 proteins were measured by immunofluorescence method.The results showed that compared with group C,groups L,I and F had no significant changes in initial body weight,final body weight,daily gain,net gain and lung index(P>0.05);the expression levels of CHOP and GRP78 proteins in groups L,I and F were significantly increased(P<0.05);the expression level of HO-1 protein in groups L and I was significantly increased(P<0.05),but the expression level of Nrf2 protein had no significant change(P>0.05);the expression level of HO-1 protein in group F was significantly decreased(P<0.05),but the expression level of Nrf2 protein was no significantly changed(P>0.05).Compared with group L,groups I and F had no significant changes in initial body weight,final body weight,daily gain,net gain and lung index(P>0.05);the expression levels of HO-1 and CHOP proteins in groups I and F were significantly reduced(P<0.05),but the expression levels of Nrf2 and GRP78 proteins had no significant changes(P>0.05).It can been seen from the above results:firstly,the expression levels of HO-1 and CHOP proteins are increased induced by lead exposure,but the expression levels of HO-1 and CHOP proteins are reduced after folic acid intervention;secondly,the oxidative stress caused by lead exposure is closely related to the Nrf2/HO-1 and GRP78/CHOP pathways,and folic acid directly affects the expression of HO-1 and CHOP proteins;thirdly,the dose of 0.4 mg/kg BW of folic acid has a certain antagonistic effect on oxidative stress and endoplasmic reticulum stress caused by 0.2%lead acetate exposure in rats with lung injury.