中叶素对糖尿病大鼠缺血再灌注心肌氧化应激的影响

Effects of intermedin on oxidative stress induced by myocardium ischemia reperfusion in diabetic rats

目的：观察中叶素对糖尿病大鼠在缺血再灌注损伤时心肌氧化应激的影响，并分析其机制。方法选取健康雄性6周龄SD大鼠（220～250 g）74只,按照随机数字表法分为5组：假手术组（NS，n=12）、缺血再灌注组（NIR，n=12）、糖尿病假手术组（DS，n=14）、糖尿病缺血再灌注组（DIR，n=18）、IMD处理组（IMD，n=18）。观察大鼠血糖、体重及血浆中叶素的变化；应用化学法测定血清中肌酸激酶同工酶（CK-MB）和乳酸脱氢酶（LDH）的活性；用比色法测定心肌组织中丙二醛（MDA）和超氧化物歧化酶（SOD）活性，同时测定心肌组织中一氧化氮合酶（NOS）和一氧化氮（NO）的含量；采用荧光定量聚合酶链反应（PCR）法检测心肌组织中P22等mRNA的表达。采用单因素方差分析各组均数之间的比较。结果给予中叶素治疗后，与DIR组相比，IMD组CK-MB、LDH活性以及心肌组织MDA含量均明显降低[分别为（1832±257）比（3916±269） U/L，（4321±196）比（4923±321）U/L，（20.9±1.3）比（26.3±0.7） nmol/mg prot，F=83.315、76.549、32.961，均P〈0.05]；IMD组心肌组织中的SOD、NOS、NO活性较DIR组明显升高（F=43.025、3.879、2.511，均P〈0.05）。此外心肌组织p22、p67和gp91RNA的表达水平在IMD组均较DIR组显著下降，差异均有统计学意义（F=3.461、2.115、7.091，均P〈0.05）。结论糖尿病可能会加重心肌缺血再灌注损伤，中叶素可能通过抑制氧化应激反应而发挥其保护糖尿病心肌缺血再灌注后损伤的作用。

Objective To observe the effects of intermedin（IMD） on oxidative stress induced by myocardial ischemia reperfusion injury in diabetic rats, investigate the mechanism of IMD on myocardial oxidative stress in diabetic status. Methods By using random number table method, 74 healthy male Sprague-Dawley （SD） rats were divided into five groups：sham group （NS,n=12）, ischemia-reperfusion （NIR, n=12）, diabetes sham group （DS,n=14）, diabetes, ischemia-reperfusion group （DIR,n=18）, IMD-treated group （IMD group, n=18）. Diabetes was induced by streptozotocin in SD rats. Animals were subjected to myocardial ischemia via left circumflex artery ligation for 30 minutes followed by 2 hours of reperfusion. IMD was administered formally 10 minutes before reperfusion in IMD group. Rat blood glucose, body weight and other state changes were measured. Serum activity of lactate dehydrogenase（LDH） and creatine kinaseisoenzyme （CK-MB）was measured by chemistry method. At the end of experiment, the activity of malondialdehyde（MDA）, superoxide dismutase （SOD, colorimetry method） and the content of nitric oxide synthase （NOS）, nitric oxide （NO） in myocardium during the reperfusion period were measured. mRNA expression of p22,p67 and gp91 in myocardial tissue was detected by fluorescence quantitative polymerase chain reaction（PCR）. Mean data between groups was analyzed by one-way ANOVA method. Results After pretreatment with IMD, the activity of serum CK-MB, LDH and MDA content in myocardial tissue decreased obviously in IMD group compared with those of DIR group（（1832 ± 257） vs （3916 ± 269）U/L, （4321 ± 196） vs （4923±321）U/L, （20.9±1.3） vs （26.3±0.7）nmol/mg prot, F=83.315,76.549,32.961,all P〈0.05）.The activity of SOD, the content of NOS, NO in myocardial were significantly elevated in IMD group when compared with those in DIR group（F=43.025,3.879,2.511,P〈0.05）.Compared with those in DIR group, p22,p67 and gp91 mRNA expression levels in myocardial tissue of IMD group decreased significantly（F=3.461,2.115, 7.091,P〈0.05）.Conclusions Diabetes could aggravate myocardial ischemia reperfusion injury.By inhibitingoxidative stress, IMD may represent a promising novel therapeutic target mitigating diabetic ischemic heart injury.