盐酸曲马多预先给药对急性心肌缺血大鼠心肌降钙素基因相关肽的影响

Effects of tramadol hydrochloride pretreatment on expression of calcitonin gene-related pepfide in myocardium following acute myocardial ischemia in rats

目的观察盐酸曲马多预先给药对急性心肌缺血大鼠心肌组织缺血区和非缺血区降钙素基因相关肽（CGRP）表达的影响，探讨痛觉干预在缺血心肌保护中的作用机制。方法健康成年雄性SD大鼠18只，体质量270～300g，随机分为3组（n=6）：假手术组（S组）、单纯冠状动脉结扎组（I组）和盐酸曲马多干预冠状动脉结扎组（T组）。S组大鼠开胸后在冠状动脉左前降支下穿线不结扎；I组大鼠开胸后结扎冠状动脉左前降支；T组大鼠经尾静脉注射盐酸曲马多12．5mg·kg^-1，15min后结扎冠状动脉左前降支。各组在手术后计时3h。采用免疫组化、酶免疫试验和反转录-聚合酶链反应从蛋白和基因水平观察各组大鼠缺血区和非缺血区心肌CGRP的表达并使用单因素方差分析进行统计学分析。结果心肌中仅检测到8．CGRPrnRNA；Ⅰ组大鼠缺血区CGRP平均光度（0．215±0．100）、阳性单位（36．95±1．70）、CGRP浓度（39．06±1．86）及β—CGRPmRNA表达（0．946±0．019）均较S组（0．139±0．006），（25．01±1．03），（20．80±1．24），（0．734±0．025）升高（P〈0．05），T组（0．158±0．008），（28．53±1．21），（28．58±2．10），（0．872±0．024）明显低于Ⅰ组（P〈0．05），但仍高于S组（P〈0．05）；I组大鼠非缺血区心肌CGRP平均光度（0．156±0．017）、阳性单位（28．57±2．23）、CGRP浓度（28．58±1．12）及B—CGRPmRNA表达（0．810±0．021）均较S组（0．109±0．013），（20．91±2．14），（17．35±2．72），（0．701±0．018）升高（P〈0．05），T组（0．120±0．008），（22．58±1．18），（23．26±2．41），（0．779±0．022）明显低于I组（P〈0．05），但仍高于S组（P〈0．05）。结论盐酸曲马多预先给药可降低急性心肌缺血大鼠心肌组织CGRP的表达，提示盐酸曲马多痛觉干预可能参与缺血心肌的保护。

Objective To investigate the effects of tramadol hydrochloride pretreatment on the expression of calcitonin gene-related peptide （CGRP） in ischemic and non-ischemic myocardium following acute myocardial ischemia in the rats. Method Eighteen adult male SD rats weighing 270 to 300 g were randomly divided into three groups （ n = 6, in each） ： group Ⅰ , sham operation; group Ⅱ , myocardial ischemia, and group Ⅲ, tramadol hydrochloride pretreatment. The anterior descending branch of left coronary artery was occluded（CAO）for 3 hours in rats of group U and Ⅲ. In group Ⅲ, tramadol hydrochloride 12.5 mg·kg^- 1 was injected through caudal vein 15 minutes before CAO. At 3 hours after myocardial ischemia, the hearts were removed for determination of CGRP protein content in ischemic and non-isehemie myocardium by immuno-histochemistry and enzyme immunometric assay, and the expression of CGRPmRNA by RT-PCR. One-way ANOVA was used for statistical analysis. Results Only β-CGRPmRNA was found in rats myocardium. In the ischemic myocardium, the average light density of CGRP（0. 215 ± 0. 100）, positive unit（36.95 ± 1.70）, concentration（39.06 ± 1.86） and expression of β-CGRP mRNA 0. 946± 0. 019） were significantly increased in group Ⅱ compared with those in group Ⅰ （0. 139 ± 0.006）, （25.01 ± 1.03）, （20.80± 1.24）, （0.734±0.025） （P 〈0.05）, and decreased markedly in group Ⅲ （0. 158± 0. 008）, （28.53 ± 1.21 ）, （28.58 ± 2.10）, （0. 872 ± 0. 024） （ P 〈 0.05） In the non-ischemic myocardium, the average light density of CGRP（0. 156±0.017）, positive unit（28.57 ±2.23）, concentration （28.58 ± 1.12） and expression of β-CGRP mRNA（0. 810± 0. 021 ） were significantly increased in group Ⅱ compared with those in group Ⅰ （0. 109 ± 0.013, 20.91± 2.14, 17.35± 2.72, 0.701 ± 0.018） （ P 〈 0.05）, and decreased markedly in group Ⅲ （0.120± 0. 008）, （22.58 ± 1.18）, （23.26 ±2.41 ）, （0. 779 ± 0. 022） （ P 〈 0.05）. Conclusions Tramadol hydrochloride pretreatment can significantly inhibit increase in CGRP expression in myocardium elicited by CAO, which might imply that tramadol hydrochloride might take part in protection of myocardlum against acute myocardial ischemia by means of pain-relief.