中枢吗啡预处理对心脏缺血后大鼠海马CaM、血浆CGRP以及下丘脑室旁核和心肌P物质表达的影响

目的探讨侧脑室内注射吗啡预处理对在体大鼠心肌缺血/再灌注损伤的影响及可能的信号机制。方法建立模型大鼠,随机分为两个部分:①分为4组,每组6只:对照组(CON组),在缺血/再灌注前30 min内,侧脑室内微量泵注射0.9%生理盐水5 min,停止注射5 min,重复3次;预处理组(MPC组),在缺血/再灌注前30 min内,侧脑室内注射吗啡(1μg.kg-1)5 min,停止5 min,重复3次;钙调蛋白抑制剂三氟拉嗪(trifluoperazine,TFP)+预处理组(TFP+MPC组),在吗啡预处理前10 min一次侧脑室内给予TFP(浓度为20 g.L-1)5μl;另设TFP自身对照组(TFP组)。②分为3组,每组6只:假手术组(Sham组),CON组和MPC组均同第一部分。观察指标包括:平均动脉压(MAP)、心率(HR),计算平均动脉压和心率乘积(RPP);心肌缺血危险区(AAR)、梗死区(IS)的体积、心肌梗死面积以IS/AAR表示;检测血浆降钙素基因相关肽(calcitonin gene related peptide,CGRP);测定海马组织钙调蛋白;测定下丘脑室旁核、心肌缺血区和非缺血区P物质的表达。结果与CON组相比,MPC组的IS和IS/AAR均明显下降(P<0.01),TFP+MPC组分别与TFP组和CON组相比差异无显著性(P>0.05),而均明显高于MPC组(P<0.01);CON组分别与Sham组和MPC组相比,其下丘脑室旁核、心肌缺血区和非缺血区P物质表达均明显增高(P<0.01,P<0.05);MPC组血浆降钙素基因相关肽CGRP水平与海马钙调蛋白的表达均明显高于其它各组(P<0.01)。结论侧脑室内注射吗啡预处理对在体大鼠心肌缺血/再灌注损伤具有保护作用,其机制可能与钙调蛋白介导释放CGRP和痛觉的干预有关。

Effects of intracerebroventricular morphine preconditioning on expression of calmodulin in hippocampus,calcitonin gene related peptide in plasma, substance P in hypothalamic paraventricular nucleus and myocardium in myocardial postischemia injury rats

Aim To investigate the protective effect of intracerebroventricular morphine preconditioning to myocardial ischemia/reperfusion injury in intact rat heart and the mechanism of this cardioprotection.Methods Rats were established intracerebroventricular catheter placement and myocardial ischemia/reperfusion models randomly assigned to two series:① four groups: control group(CON);intracerebroventricular morphine preconditioning group(MPC);trifluoperazine,a calmodulin antagonist intracerebroventricular 10 min before intracerebroventricular morphine(TFP+MPC) and itself control(TFP).② three groups: Sham group(Sham),CON and MPC.Indicators to be observed were composed of MAP,HR and RPP(MAP×HR);the volume of area at risk(AAR),infarct size(IS) and the area of myocardial infarction,were demonstrated by IS/AAR.Meanwhile,the CGRP in the blood plasma was tested by radioimmunity protocol.The epression of calmodulin in the hippocampus was determined by Western blot.Expressions of SP in the hypothalamic paraventricular nucleus,ischemia and non-ischemia myocardium area were determined by immunohistochemical method.Results Compared with other groups,the volume of IS and IS/AAR reduced in MPC group(P<0.01);the calcitonin gene related peptide(CGRP) in the blood plasma and expression of calmodulin in the hippocampus were higher than that of other groups(P<0.01).Compared with CON group,integrated optical density of SP in MPC group expressed in paraventricular hypothalamic nucleus,ischemia and non-ischemia myocardial were lower(P<0.01,P<0.05).Conclusions Intracerebroventricular morphine preconditioning can produce cardioprotective effect against ischemia/reperfusion injury,which involves in CGRP mediated by calmodulin in hippocampus and also associated with analgesia.