ABSTRACT
Objective To evaluate the role of classⅠhistone deacetylase (HDAC) in myocardial ischemia-reperfusion (I∕R) injury in diabetic rats and the relationship with adenosine monophosphate-acti- vated protein kinase (AMPK)∕mammalian target of rapamycin (mTOR) signaling pathway. Methods SPF healthy adult male Sprague-Dawley rats, weighing 210-220 g, were used in this study. Type I diabetes mellitus was induced by single intraperitoneal injection of streptozotocin dissolved in citrate buffer 60 mg∕kg, and 8 weeks later the rats with type I diabetes mellitus were used for experiment. Forty-eight diabetic rats were divided into 4 groups (n＝12 each) by using a random number table method: sham operation group (group S), myocardial I∕R group (group I∕R), myocardial I∕R plus class I HDAC inhibitor MS-275 group (group I∕R+MS) and myocardial I∕R plus MS-275 plus AMPK inhibitor Compound C group ( group I∕R+MS+CC). Myocardial I∕R was induced by ligation of the left anterior descending branch of the coronary ar-tery for 45 min followed by 180 min of reperfusion in anesthetized rats. In group I∕R+MS, MS-275 10 mg∕kg was intraperitoneally injected once a day for 7 consecutive days, and myocardial I∕R was produced after the end of administration. AMPK inhibitor Compound C 0. 5 mg∕kg was intravenously injected at 30 min before ischemia in group I∕R+MS+CC. Six rats were sacrificed at the end of reperfusion for determina-tion of myocardial infarct size. Another 6 rats were selected at the end of reperfusion and sacrificed for deter-mination of the level of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) in serum (by en-zyme-linked immunosorbent assay), expression of AMPK, phosphorylated AMPK ( p-AMPK), mTOR, phosphorylated mTOR (p-mTOR), ubiquitin-binding protein P62 (P62), microtubule-associated protein 1 light chain 3 Ⅰ(LC3 Ⅰ) and LC3Ⅱ in myocardial tissues (by Western blot). The ratios of p-AMPK∕AMPK, p-mTOR∕mTOR and LC3Ⅱ∕Ⅰwere calculated. Results Compared with group S, the myocardial infarct size and levels of serum CK-MB and LDH were significantly increased in I∕R, I∕R+MS and I∕R+M+CC groups, the ratios of p-AMPK∕AMPK and LC3Ⅱ∕Ⅰwere significantly increased, p-mTOR∕mTOR ratio was decreased, and P62 expression was down-regulated in group I∕R+MS (P＜0. 05), and no significant change was found in p-AMPK∕AMPK ratio, p-mTOR∕mTOR ratio, LC3Ⅱ∕Ⅰ ratio or P62 expression in I∕R and I∕R+M+CC groups (P＞0. 05). Compared with group I∕R, the myocardial infarct size and levels of serum CK-MB and LDH were significantly decreased, the ratios of p-AMPK∕AMPK and LC3Ⅱ∕Ⅰwere in-creased, p-mTOR∕mTOR ratio was decreased, and P62 expression was down-regulated in group I∕R+MS (P＜0. 05), and no significant change was found in the parameters mentioned above in group I∕R+M+CC (P＞0. 05). Compared with group I∕R+MS, the myocardial infarct size and levels of serum CK-MB and LDH were significantly increased, the ratios of p-AMPK∕AMPK and LC3Ⅱ∕Ⅰ were decreased, p-mTOR∕mTOR ratio was increased, and P62 expression was up-regulated in group I∕R+M+CC ( P＜0. 05). Con-clusion Class Ⅰ HDAC is involved in myocardial I∕R injury through enhancing AMPK∕mTOR signaling pathway-regulated level of autophagy in diabetic rats.
ABSTRACT
Acute myocardial ischemia and reperfusion led to arrhythmias and increase of glutamic oxalacetic transaminase (GOT),lactate dehydrogenase (LDH),non-csterified fatty acid (FFA) and malondialdehyde (MDA) content, and decrease of superoxide dismutase (SOD) activity in rats. 3, 6-di-methylamino-dibenzopyri-odonium edetate (IHC-72) 5 mg?kg-1 iv significantly reduced the incidence of ventricular tachy-cardia (VT) and ventricular fibrillation(VF) ,shortened the duration of arrhythmias induced by reperfusion, decreased the release of GOT, LDH and FFA, obviously reduced the MDA content,and effectively protected SOD activity in ischemia-reperfused rat hearts. Our experimental results suggested that IHC-72 had protective effects on ischemia-reperfusion injury rat hearts in vivo. The mechanism of the protection might be associated with the inhibition of cellular lipid peroxidation.