心肌梗死模型大鼠梗死区周围心肌C3G蛋白的表达变化及其意义

Change in C3G protein expression in the peri-infarct myocardium and its significance in rats

目的观察心肌梗死模型大鼠梗死区周围心肌C3G蛋白表达的改变及其意义。方法健康雄性SD大鼠随机分为心肌梗死组和假手术组,按照Litwin方法建立实验性大鼠心肌梗死及假手术模型。于术后24h和12周处死两组大鼠,收集心肌标本。取心尖部心肌(心肌梗死组取含梗死区的心肌组织),采用苦味酸天狼星及免疫组化方法检测心肌Ⅰ、Ⅲ型胶原容积(CVFⅠ、Ⅲ)及C3G蛋白表达情况;取心底部心肌(心肌梗死组取非梗死区的心肌组织),采用Western blotting检测C3G蛋白的相对表达量。结果苦味酸天狼星染色结果显示,心肌梗死后12周组心肌细胞中CVFⅠ、Ⅲ分别为14.01±2.73、4.80±0.64,明显高于假手术后24h组(3.15±0.70、1.42±0.48),心肌梗死后24h组(3.68±0.95、1.53±0.61)以及假手术后12周组(3.27±0.65、1.47±0.52),差异有统计学意义(P<0.05),而后3组间差异无统计学意义(P>0.05)。免疫组化检测显示,心肌梗死后12周组心肌中C3G蛋白表达较其他3组均显著增加(P<0.05),而后3组间比较无明显差异(P>0.05)。Western blotting检测显示,与假手术后12周组(0.22±0.04)、假手术后24h组(0.22±0.04)、心肌梗死后24h组(0.29±0.02)比较,心肌梗死后12周组梗死区周围心肌C3G蛋白表达(0.56±0.06)显著增加(P<0.05)。结论心肌中存在C3G蛋白表达。发生心肌梗死后,梗死区周围心肌C3G蛋白表达水平显著增加,提示C3G蛋白参与了梗死后的心肌重塑。

Objective To investigate the change in expression of C3G protein, a Crk SH3 domain-binding guanine nucleotide-releasing factor, in the peri-infarct myocardium in rats. Methods Male SD rats were randomly divided into experimental myocardial infarction （MI） group and sham-operated （SO） group using Litwin method. The rats in the MI and SO groups were sacrificed at 24 hours and 12 weeks after the operation, and the myocardium was harvested from the cardiac apex in the SO group and the infarct area in the MI group for determination of types Ⅰ and Ⅲ collagen and C3G protein expression with picric acid-sirius red staining and immunohistochemistry. Non-infarcted myocardium in the MI group and the normal myocardium in the SO group were havrested for measuring the relative expression level of C3G protein by Western blotting. Results The picric acid-sirius red staining showed that types Ⅰ and Ⅲ collagen volume was respectively 14.01± 2.73 and 4.80 ± 0.64 12 weeks after MI, 3.15± 0.70 and 1.42±0.48 24 hours after SO, 3.68±0.95 and 1.53±0.61 24 hours after MI, and 3.27 ±0.65 and 1.47 ±0.52 （P〈0.05） 12 weeks after SO. However, there was no difference between the latter three groups （P〉0.05）. Western blotting revealed that the C3G protein expression 12 weeks after MI was significantly increased compared with that in the other three groups （P〈0.05）, but there was no difference between the latter three groups （P〉0.05）. C3G protein expression in the non-infarct myocardium at 12-week post MI （0.56± 0.06, n=8） was significantly higher as compared with that in the cardiac apex 12 weeks （0.22 ±0.04, n=8）, 24 hours （0.22 ±0.04, n=8） after SO and in the non-infarct myocardium 24 hours after MI （0.29± 0.02, n=8） respectively （All P〈0.05）. Conclusions C3G protein exists in the myocardium in rats. C3G protein expression could significantly increase in the peri-infarct myocardium. The increased C3G protein expression could be involved in post-infarction cardiac remodeling.