卡维地洛对低温应激高血压大鼠心肌内质网GRP78和CHOP的表达及心肌细胞凋亡的影响

摘要

Objective To explore the effect of beta-blocker carvedilol on myocardial endoplasmic reticulum by comparing changes in the expressions of glucose regulation protein 78(GRP78)and C/EBP homologous protein(CHOP)and apoptosis of myocar-dial cells in hypothermic stress-induced hypertensive rats.Methods Thirty male SD rats were randomly divided into the sham group, the CIH group and the carvedilol group,each consisting of 10 animals.The rats in the CIH and carvedilol groups were kept in an envi-ronment at a temperature of(4 ±1)℃and relative humidity of 70% for 4 hours every day for the development of hypothermic stress-in-duced hypertension model.The animals in the carvedilol group received medication of carvedilol by gavage a week before surgery.Blood pressure values of each group were determined by carotid artery intubation 6 weeks after experiment started.The expression levels of GRP78 and CHOP proteins were detected by immunohistochemical method,and apoptosis of myocardial cells was detected by TUNNEL method.Results (1)The mean arterial pressure(MAP)of the animals in the carvedilol group [(118.80 ±3.40)mmHg] was signifi-cantly lower than that of the animals in the CIH group(165.20 ±4.40 mmHg),but was higher than that of the animals in the sham group(107.2 ±0.3mmHg).Statistical significance could be seen, when comparisons were made between them(P<0.05).MAP level of the CIH group was higher than that of the sham group,also with statistical significance(P<0.05).(2)The average optical density(AOD)in the expression of GRP78 protein for the CIH group(0.34 ±0.03)was higher than that of the sham group(0.16 ± 0.02),and statistical significance could be noted,when comparisons were made(P<0.05).For the carvedilol group,the AOD level in the expression of GRP78 was significantly lower than that of the CIH group(0.20 ±0.02),but slightly higher than that of the shame group,also with statistical significance(P<0.05).(3)The AOD level in the expression of CHOP protein for the CIH group(0.45 ± 0.03)was higher than that for the sham group(0.05 ±0.02), and there was statistical significance when comparisons were made (P<0.05).The AOD level in the expression of CHOP protein for the carvedilol group(0.21 ±0.02)was significantly lower than that for the CIH group,but slightly higher than that for sham group, also with statistical significance(P<0.05).(4)Research results showed that apoptosis rate of myocardial cells for the CIH group [(16.31 ±1.96)%] was higher than that for the sham group[(2.40 ±0.88)%],and there was statistical significance when comparisons were made between them(P<0.05).The apoptosis rate of the carvedilol group(7.43 ±1.22%)was significantly lower than that of the CIH group,but slightly higher than that of the sham group, also with statistical significance(P<0.05).Conclusion Carvedilol could decrease GRP78 and CHOP expression levels of myocardial cells in hypertensive cardiomyocytes,and lower the level of endoplasmic reticulum stress(ERS), the protective mechanism of which might be associated with the intervention of ERS-mediated cardiomyocytes reconstruction.%目的 通过对比葡萄糖调节蛋白78(glucose-regulated protein78,GRP78)和C/EBP同源蛋白(C/EBP homologous protein,CHOP)的表达及心肌细胞凋亡的变化,探讨β受体阻滞剂卡维地洛对低温应激诱发高血压大鼠心肌内质网应激的影响.方法 30只雄性SD大鼠按数字表法随机分为对照(Sham)组、低温应激高血压(cold-induced hypertension,CIH)组和卡维地洛(Carvedilol)组,每组10只.CIH组和Carvedilol组大鼠每天置于温度为(4 ±1)℃,湿度为70%环境4 h,建立低温应激高血压大鼠模型,Carvedilol组术前1周开始给予卡维地洛灌胃.6周后用颈动脉插管法测定各组大鼠血压值,免疫组化法检测GRP78蛋白和CHOP蛋白的表达水平,TUNNEL法检测心肌细胞凋亡.结果 (1)Carvedilol组平均动脉压(mean arterial pres-sure,MAP)[(118.80 ±3.40)mmHg]显著低于CIH组[(165.20 ±4.40)mmHg],但高于Sham组[(107.2 ±3.8)mmHg],差异均有统计学意义(P<0.05);CIH组MAP水平高于Sham组,差异有统计学意义(P<0.05).(2)CIH组GRP78蛋白表达的平均光密度(average optical density,AOD)值(0.34 ±0.03)高于Sham组(0.16 ±0.02),差异有统计学意义(P<0.05);Carvedilol组GRP78蛋白表达的AOD值(0.20 ±0.02),显著低于CIH组,但略高于Sham组,差异均有统计学意义(P<0.05).(3)CIH组CHOP蛋白表达的AOD值(0.45 ±0.03)高于Sham组(0.05 ±0.02),差异有统计学意义(P<0.05);Carvedilol组CHOP蛋白表达的AOD值(0.21 ±0.02)著低于CIH组,但略高于Sham组,差异有统计学意义(P<0.05).(4)CIH组心肌细胞凋亡率[(16.31 ±1.96)%]高于Sham组[(2.40 ±0.88)%],差异有统计学意义(P <0.05);Carvedilol 组心肌细胞凋亡率[(7.43 ± 1.22)%]显著低于CIH组,但略高于Sham组,差异有统计学意义(P<0.05).结论 卡维地洛能够通过降低低温应激高血压心肌细胞GRP78和CHOP的表达,下调心肌细胞内质网应激(endoplasmic reticulum stress,ERS)水平,其对心肌的保护机制可能与其干预了ERS介导的心肌细胞重构有关.