黄芪多糖对严重烧伤大鼠心肌损伤的保护作用

Protection of Astragalus polysaccharides on myocardial damage in severely burned rats

目的观察黄芪多糖对严重烧伤大鼠心肌细胞凋亡的影响,并探讨其作用机制。方法 120只大鼠随机分为对照组、模型组、地塞米松(5 mg/kg)组和黄芪多糖10、20、40 mg/kg组,每组20只。采用92℃水浴18 s的方法制备大鼠30%总体表面积占比(TBSA)III度烧伤模型。各治疗组均ip给药1 m L/kg;对照组、模型组均ip给予生理盐水1 m L/kg。24 h后,TUNEL法检测心肌细胞凋亡情况并计算凋亡指数,测定血清中心肌酶天冬氨酸氨基转移酶(AST)、肌酸磷激酶(CPK)、乳酸脱氢酶(LDH)和肌钙蛋白T(c Tn T)水平,测定心肌组织中抗氧化酶超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、髓过氧化物酶(MPO)活性和丙二醛(MDA)含量;RT-PCR法检测心肌组织中AKT mRNA、bcl-2 mRNA、Bax mRNA表达并计算bcl-2/Bax表达比值;Western blotting法检测心肌组织中caspase-3、NF-κB蛋白表达。结果与模型组比较,黄芪多糖组大鼠心肌细胞凋亡数量明显减少。与模型组比较,黄芪多糖20、40 mg/kg治疗24 h能够显著降低严重烧伤大鼠心肌细胞凋亡指数;AST、CPK、LDH、c Tn T水平显著降低;SOD、CAT、MPO活性显著升高,MDA含量显著降低;AKT mRNA、bcl-2 mRNA表达显著上调、Bax mRNA表达显著下调,bcl-2/Bax比值显著升高;显著降低caspase-3、NF-κB蛋白表达量(P<0.05、0.01)。结论黄芪多糖对严重烧伤大鼠心肌损伤具有保护作用,其作用机制可能与黄芪多糖能够有效降低氧化应激损伤和调节凋亡相关基因和蛋白表达有关。

Objective To investigate the protective effects of Astragalus polysaccharides on myocardial damage in severely burned rats, and discuss its mechanism. Methods Totally 120 rats were randomly divided into control group, model group, dexamethasone（5 mg/kg） group, and Astragalus polysaccharides（10, 20, and 40 mg/kg） groups, and each group had 20 rats. The model rats with 30% TBSA（III degree） were made by bathing in 92 ℃ water for 18 s. The rats in treatment groups were ip injected with the 1 mL/kg drugs, but rats in control and model groups were ip administered with 1 mL/kg normal saline. After 24 h, the apoptosis of cardiomyocytes was observed by TUNEL staining, and the apoptosis index was calculated. The contents of AST, CPK, LDH, and c Tn T in serum were determined. The activities of SOD, CAT, and MPO, and the content of MDA in myocardial tissue were measured. The expression of AKT mRNA, Bax mRNA, and bcl-2 mRNA was determined by RT-PCR method, and the ratio of bcl-2/Bax was calculated. The expression of caspase-3 and NF-κB was determined by Western blotting. Results Compared with model group, the cardiomyocytes apoptosis in Astragalus polysaccharides groups were significantly improved. Compared with model group, the apoptosis index of Astragalus polysaccharides（20 and 40 mg/kg） groups were significantly decreased; The levels of AST, CPK, LDH, and c Tn T in serum were significantly decreased; The activities of SOD, CAT, and MPO were significantly increased, but the content of MDA was significantly decreased; The expression of AKT mRNA and Bax mRNA were significantly up-regulated and the Bax mRNA was significantly down-regulated, the ratio of bcl-2/Bax was significantly increased. The expression of caspase-3 and NF-κB were significantly decreased（P〈0.05, 0.01）. Conclusion Astragalus polysaccharides has protection on myocardial damage in severely burned rats, which might be related to reduce oxidative stress injury and regulate the expression of apoptosis-related genes and protein.