摘要
目的:研究糖尿病心肌病(DCM)模型大鼠心肌组织中X-盒结合蛋白1(XBP1)与心肌细胞凋亡之间的联系,以及明确缬沙坦抑制心肌细胞凋亡的作用机制。方法:将清洁级雄性8周龄Wistar大鼠50只随机分为两部分:腹腔注射65 mg/kg的柠檬酸盐缓冲液的大鼠为对照组(n=10);腹腔注射链脲佐菌素65 mg/kg大鼠(n=40)注射7天后,收集大鼠尾静脉血测空腹血糖,其中37只连续2次空腹血糖≥16.7mmol/L(300mg/dl)为DCM大鼠建模成功并将其随机分为2组:给予以生理盐水灌胃的为DCM组(n=20),以30mg/kg·d灌胃缬沙坦给药的为DCM+缬沙坦组(n=17)。三组大鼠饲养过程中检测体重、血糖、血压、心功能等指标变化。大鼠16周后处死观察心肌组织结构、细胞形态、胶原分布情况,TUNEL染色观察心肌细胞凋亡,并通过免疫荧光、蛋白印迹法(Western blot)、实时定量逆转录-聚合酶链反应(RT-PCR)及半定量RT-PCR检测各组大鼠心肌组织中cytochrome c、cleaved caspase 3、葡萄糖调节蛋白78(GPR78)和剪接型XBP1(XBP1-s)表达水平。结果:DCM组大鼠与对照组相比,心肌结构紊乱,胶原含量明显增加,心肌细胞凋亡增加(P<0.05),GRP78、XBP1-s、cleaved caspase 3和cytochrome c蛋白及核糖核酸(RNA)表达水平明显升高(P<0.05),DCM+缬沙坦组与DCM组相比,心肌细胞排列较整齐,心肌间质内和小动脉周围胶原纤维显著减少,心肌细胞凋亡明显减少(P<0.05),GRP78、XBP1-s、cleaved caspase 3和cytochrome c蛋白及RNA表达水平明显下降(P<0.05)。结论:DCM大鼠心肌组织中存在着调节内质网应激的关键因子-XBP1的活化,DCM病程中存在着XBP1调控的内质网应激相关凋亡途径的激活,心肌细胞凋亡增加,而缬沙坦能够抑制DCM大鼠心肌细胞XBP1的激活,减少心肌细胞凋亡。
Objective： To study the relationship between myocardial X-box binding protein 1 （XBP1） expression and myocardial apoptosis in experimental diabetic cardiomyopathy （DCM） rat’s model and to clarify the mechanism of valsartan inhibiting myocardial apoptosis. Methods： A total of 50 Wistar rats were divided into 2 groups： Control group, the rats received intraperitoneal citrate buffer at 65mg/kg,n=10 and Streptozotocin group, the rats received intraperitoneal streptozotocin at 65mg/kg,n=40, all animals were treated for 7 days. DCM model was established in 37 rats （fasting blood glucose ≥ 16.7mmole/L） and they were further divided into 2 groups： DCM group, the rats received intragastric normal saline,n=20 and DCM ＋ valsartan group, the rats received intragastric valsartan at 30mg/kg＆#183;day,n=17. The rats were treated for 16 weeks. The body weight, tail blood pressure, glucose and cardiac function were compared among 3 groups. Myocardial apoptosis was detected by TUNEL staining, RNA and protein expressions of myocardial cytochrome C, cleaved caspase 3, glucose regulation protein 78 （GRP78） and XBP1-s were examined by immunolfuorescence, real time RT-PCR and Western blot analysis. Results： Compared with Control group, DCM group showed disordered cardiac structure, more collagen content and myocardial apoptosis,P〈0.05; increased RNA and protein expressions of GRP78, XBP1-s, cleaved caspase 3 and cytochrome C,P〈0.05. Compared with DCM group, DCM ＋ valsartan group had rather regularly arranged myocardiocytes, less interstitial ifbrosis and myocardial apoptosis,P〈0.05; decreased RNA and protein expressions of GRP78, XBP1-s, cleaved caspase 3 and cytochrome C,P〈0.05. Conclusion： Valsartan may inhibit myocardial XBP1 activation and therefore, reduce the myocardial apoptosis in experimental DCM rat’s model.
出处
《中国循环杂志》
CSCD
北大核心
2014年第10期836-840,共5页
Chinese Circulation Journal
