卡维地洛对大鼠急性心肌梗死后心肌细胞凋亡和bcl-2/bax基因表达的干预作用

Beneficial effects of carvedilol on cardiomyocyte apoptosis and bcl-2/bax expression after acute myocardial infarction an experiment with rats

目的评价新一代β受体阻断剂卡维地洛对大鼠急性心肌梗死(AM I)后心肌细胞凋亡及其相关基因表达的干预作用。方法将冠状动脉结扎术后24 h存活的雌性SD大鼠(83只)分为AM I对照(M I组,43只)和卡维地洛(10 mg.kg-1.d-1)治疗组(C组,40只),另设假手术组(S组,27只)。各组再按观察时点分为48 h和4周两个亚组。C组于术后24 h直接灌胃法给药。用TUNEL法和DNA凝胶电泳检测心肌细胞凋亡。用免疫组化方法和W estern印迹法检测“抑制凋亡复合基因”bc l-2/bax的表达。结果(1)M I组梗死/瘢痕区、梗死边缘区和非梗死区的心肌细胞凋亡指数(48 h 21.2%±15.6%、19.8%±12.0%和6.3%±4.5%;4周23.5%±13.0%、8.0%±4.4%和3.2%±1.6%)高于假手术组(48 h 1.3%±1.1%,4周1.2%±0.3%,均P<0.05);凋亡促进基因bax的表达M I48 h组明显高于假手术组,但“凋亡抑制基因”bc l-2仅在M I48 h组梗死区心肌细胞中表达增加;bc l-2/bax的比值M I48 h组(1.06)低于假手术组(1.87)。(2)C48 h组3个区域的心肌细胞凋亡指数与M I组比较,差异无统计学意义(均P>0.05),但梗死区及边缘区bc l-2的表达均增加;C4周组梗死/瘢痕区及边缘区的心肌细胞凋亡指数(4.0%±2.0%,2.9%±1.6%)均低于M I组(23.5%±13.0%,8.0%±4.4%,均P<0.05),且瘢痕区心肌细胞中bax的表达亦明显降低,但bc l-2的表达均无明显变化;C组大鼠48 h和4周时的心肌细胞bc l-2/bax的比值(1.72,2.23)高于M I组(1.06,1.8),与假手术组(1.87,2.25)相当。结论大鼠出现AM I后,长时间(4周)用卡维地洛治疗能有效防止梗死/瘢痕区及其边缘区心肌细胞凋亡的发生,并使bc l-2/bax的比值增加。

Objective To investigate the beneficial effects of carvedilol on cardiomyocyte apoptosis and related gene expression after acute myocardial infarction （AMI）. Methods Eighty-three female SD rats underwent ligation of left anterior descending coronary artery, and were randomly assigned to 2 groups 24 hours later： carvedilol（n =40, 10 mg · kg^-1 · d^-1was administered via direct gastric gavage 24 hs after the ]igation, Group C）and AMI control group （n = 43, normal saline of the same volume was given by gastric gavage, Group MI）. Another 27 rats were used as sham operation group （ Group S, administered with normal saline too）. The rats of each group were killed and their hearts were taken out 48 hours and 4 weeks after observation respectively （MI-48 h, MI-4 week, C-48 h, C-4 week, S-48 h, and S-4 week subgroups）. TUNEL and DNA gel electrophoresis were used to detect the cardiomyocyte apoptosis. Immunohistochemistry and Western blotting were used to detect the expression of bcl-2 and bax. Results The apoptotic indices of the infracted/scar, border and non-infarcted areas at any time-point of Group MI were all significantly higher than those of Group S （ all P 〈0.05）. Only the apoptotic indices of the infracted/scar and border areas of the C-4 week subgroup were significantly lower than those of the MI-4 week subgroup （ beth P 〈 0.05 ）, and were close to those of the non-infarcted area. DNA gel electrophoresis showed that the positive rate of Group S at any time-point were both 0, the positive rate of MI-48 h subgroup and C-48 h subgroup were both significantly higher than that of Group S （ both P 〈 0.05 ） without significant difference between these 2 groups, and the positive rates of the MI-4 week subgroup and C-4 week subgroup were both 0. Immunohistochemistry showed that the hax gene expression was slightly to significantly increased in the infarcted/scar, border, and non-infarcted areas of the MI-48 h and MI-4 week subgroups. The bcl-2 expression was significantly increased only in the infracted area of the MI-48 h subgroup. The bcl-2 expression was slightly increased in the infracted and border areas of the C-48 h subgroup and the hax expression was significantly decreased in the infracted/sear area of the C-4 week subgroup. Western blotting showed that ①the bcl-2 expression of the S-4 week subgroup was significantly higher than that of the S-48 h subgroup （ P 〈 0.05 ）, ②the bel-2 expression and bax expression of the MI-48 h subgroup were significantly higher than that of the S-48 h subgroup （P 〈 0.05 - 0.01 ）, the bcl-2/bax ratio of the MI-48 h subgroup was significantly lower that that of the S-48 h subgroup, however, there were no significant differences in the bcl- 2 and bax expression and bcl-2/bax ratio between the MI-4 week subgroup and S-48 h subgroup （ all P 〉 0. 05）. and ③There were no significant difference in the bel-2 and bax expression between Group A and Group S （ all P 〉 0. 05 ） , however, the bcl-2/bax ratios at the 2 time-points of Group C were both significantly higher than those of Group MI. Conclusion Cardiomyocyte apoptosis occurs in the infarction/ scar, border and non-infarcted areas after AMI. Prolonged treatment with carvedi]ol reduces cardiomyocyte aimptosis in the scar and border areas and increases the expression ratio of hcl-2/bax.