心肌缺血/再灌注损伤后瘦素的改变及机制初探

目的 观察大鼠心肌缺血/再灌注(I/R)损伤对瘦素(Leptin)、内皮素(ET)、C-反应蛋白(CRP)表达的影响,探讨Leptin在心肌I/R损伤中的作用.方法 将50只SD大鼠按随机数字表法分为假手术组、缺血组及I/R 1、2、3 h组,每组10只.以结扎左冠状动脉(冠脉)前降支45 min、再通1、2、3 h建立大鼠心肌I/R损伤模型;假手术组仅穿线、不结扎冠脉.各组于相应时间点取左股动脉血,检测血清Leptin、ET、CRP的浓度;取心肌组织行苏木素-伊红(HE)染色和免疫组化,观察心肌组织病理改变及Leptin蛋白表达水平.结果 缺血组血清Leptin含量(μg/L)显著低于假手术组(4.69±1.67比6.48±2.02,P＜0.05),随再灌注时间的延长,Leptin水平逐渐升高,至I/R 3 h时已恢复到损伤前水平(6.59±2.58)μg/L].缺血组血清ET水平(ng/L)显著高于假手术组(110.58±37.86比80.74±34.43,P＜0.05),I/R 1、2、3 h组血清ET水平均显著低于缺血组(35.87±13.56、31.98±10.88、34.56±14.37比110.58±37.86,均P＜0.05).缺血组血清CRP水平(mg/L)显著高于假手术组(13.12±4.82比3.24±1.72,P＜0.01),随再灌注时间延长,CRP水平逐渐升高,I/R 1、2、3 h组均显著高于缺血组(18.37±6.48、24.30± 9.51、27.08±8.32比13.12±4.82,均P＜0.05).HE染色显示,缺血心肌细胞发生坏死、脱落,肌间质轻度充血、水肿;I/R损伤后心肌细胞呈灶性凝固性坏死,肌间质重度充血.免疫组化显示,心肌Leptin蛋白表达呈损伤后早期降低、后期升高的整体趋势.结论 在心肌I/R损伤时血清及心肌组织中Leptin水平早期明显减少,恢复期缓慢升高,提示其可能作为机体的一种应激保护因子,对抗I/R引起的心肌损伤,并可能与ET的先升后降、CRP的升高有一定的关系.

Preliminary investigation of the changes and mechanism of Leptin after myocardial ischemia/reperfusion injury

Objective To explore the effect of rat myocardial ischemia/reperfusion (I/R) injury on serum Leptin, endothelin (ET), C-reactive protein (CRP) and myocardial Leptin expression, and discuss the role of Leptin in myocardial I/R injury.Methods Fifty Sprague-Dawley (SD) rats were randomly divided into sham-operation, ischemia and I/R 1, 2, 3 hours groups, with 10 rats in each group.Anterior descending artery of the left coronary artery was ligated for 45 minutes and released for 1, 2 and 3 hours to establish myocardial I/R model, and the said artery of the rats in sham-operation group was not ligated.Blood from left femoral artery was collected at different time points, and serum Leptin, ET and CRP contents were detected.Myocardial tissue was harvested, and stained with hematoxylin-eosin (HE)and immunohistochemistry for its observation of the myocardial pathological changes and Leptin protein expression.Results Serum Leptin content (μg/L) of ischemia group was significantly lower than that of sham-operation group (4.69 ± 1.67 vs.6.48 ± 2.02, P＜ 0.05); as the reperfusion time was prolonged,serum Leptin level increased gradually, and the level of I/R 3-hour group recovered to that before injury (6.59±2.58) μg/L].ET content (ng/L) of ischemia group was significantly higher than that of sham-operation group (110.58 ± 37.86 vs.80.74 ± 34.43, P＜0.05), the levels of ET in I/R 1, 2 and 3 hours groups were significantly lower than those of ischemia group (35.87 ± 13.56, 31.98 ±10.88,34.56±14.37 vs.110.58±37.86, all P＜0.05).CRP content (mg/L) of ischemia group was significantly higher than that of sham-operation group (13.12±4.82 vs.3.24±1.72,P＜0.01); as the reperfusion time was prolonged, serum CRP level increased gradually,and the levels of I/R 1, 2 and 3 hours groups were significantly higher than those of ischemia group (18.37 ± 6.48, 24.30 ± 9.51, 27.08 ± 8.32 vs.13.12 ±4.82, all P＜0.05).Pathological examination showed that there was necrosis of ischemic myocardial cells in ischemia group, with mild congestion and edema in interstitial spaces.After I/R injury, the myocardial cells showed coagulative necrosis, and there was severe congestion of myocardial interstitia.Immunohistochemistry results showed that there was a tendency of decrease in Leptin protein expression in the early phase but increase in the late phase after the injury.Conclusion Leptin content in the serum and myocardial tissue decreases significantly in the early phase after myocardial I/R but increases gradually in the rehabilitative phase, suggesting that Leptin maybe a stress protective factor against I/R-induced myocardial injury.There is a possible association between Leptin and the early increase followed by a delayed decrease of ET as well as the increase of CRP.