p38 MAPK抑制物对大鼠心肌缺血再灌注损伤的保护作用及凋亡信号通路的影响

目的探讨p38 MAPK抑制物SB20358(SB)对心肌缺血再灌注(I/R)损伤的保护作用及凋亡信号通路的影响。方法选择45只250~300 g雄性SD大鼠,通过阻断其左冠状动脉前降支(LAD)30 min再灌注180 min制备I/R损伤模型。随机分3组(n=15):溶剂对照组(Vehicle组)、低剂量SB预处理组(SB-L组)和高剂量SB预处理组(SB-H组);同时选取15只同周龄SD大鼠仅穿线但不结扎(Sham组)。SB-L组和SB-H组分别于LAD结扎前30 min注射50μg/kg、100μg/kg SB,其余两组注射等体积的生理盐水。分别在术前(T0)、缺血30 min后(T1)、再灌注60 min(T2)、120 min(T3)及180 min后(T4)检测各组血浆肿瘤坏死因子(TNF-α)水平及I/R后的心功能情况舒张末期压力(LVEDP)、左室收缩期平均压(LVSP)、短轴缩短率(FS)和射血分数(EF)],处死大鼠并通过TTC染色分析缺血程度和梗死程度,将心脏组织包埋并采用HE染色观察各组的心肌形态学变化,同时采用Western blot检测心肌梗死区p38及其磷酸化形式的p-p38的蛋白水平。结果与Sham组相比,Vehicle组除T0外的I/R其余时间点的TNF-α水平均升高,LVSP、FS和EF均降低,LVEDP、心肌p-p38/p38值及缺血和梗死程度均升高(P0.05),心肌肌纤维出现断裂溶解及坏死,心肌间质出现水肿且间隙增大,出现坏死灶;给予SB处理后可减轻以上异常指标及心肌病理改变,与Vehicle组的差异均有统计学意义,但仍与Sham组有差异(P0.05)。SB-H组的改善效果优于SB-L组(P0.05)。结论 SB对大鼠心肌I/R损伤有改善作用,可降低心肌缺血及梗死程度,改善心功能和炎症反应并抑制p38 MAPK信号通路活化。

Protective effect of p38 MAPK inhibitors on myocardial ischemia - reperfusion injury and apoptosis signaling pathway

Objective To explore the protective effect of p38 MAPK inhibitors on myocardial isehemia - reperfusion （I/R） injury and ap- optosis signaling pathway. Methods Forty - five male SD rats weighing 250 ~ 300 g were subjected to 30 rain occlusion and 120 min reperfusion of the left anterior descending coronary artery （LAD） to induce the I/R injury model. The rats with I/R injury were divided into three groups with 15 for each group： solvent control （vehicle） group, low -dose SB pretreatment （SB -L） group and high -dose SB pretreatment group （SB -H） group. Fifteen age - matched SD rats without ligation were selected as sham group. The SB - L group and SB - H group were injected 50, 100 Ixg SB 30min before LAD ligation. The other two groups were injected with same volume of saline. The levels of plasma tumor necrosis factor （ TNF - or） were measured preoperative （ TO ） , 30 rain after ischemia （ Tl ） , 60 rain （ T2 ）, 120 rain （ T3 ） and 180 rain after （ T4 ） reperfusion. The car- diac function after I/R （ end - diastolic pressure LVEDP, left ventricular systolic mean pressure LVSP, FS fractional shortening and ejection frac- tion EF） were investigated. The rats were sacrificed and TTC staining was used to detect the degree and extent of ischemic and infarction. The heart tissue was embedded and the morphological changes were observed by HE staining. The protein levels of p38 and its phosphorylated form of p - p38 were investigated. Results Compared with sham group, there were higher levels of TNF - or,lower levels of LVSP, FS and EF, and ele- vated LVEDP, myocardial ratio of p - p38/p38, extent of ischemia and infarction in vehicle group with significant difference. There were dissolved and necrotic muscle fibers, increased myocardial interstitial gap and edema in Vehicle group. SB can mitigate the above anomalies and cardiac pa- thology with statistically significance with sham group and vehicle group （ P 〈 O. 05 ）. There was an enhancing effect in SB - H group versus SB - L group with significant differences （ P 〈 0.05 ）. Conclusion SB can mitigate the I/R injury with the effect of decreasing extent of ischemia and infarction and improvement on cardiac function and inflammation.