The Effects of Carvedilol on the Gene Expression of bcl-2 and bax in Heart in Rats

Objective To study the effects of carvedilol on the gene expression of bcl-2 and bax in heart in rats. Methods SD rats were divided into three groups: control group, adriamycin group, adriamycincarvedilol group. The models of myocardium toxicity were prepared using intraperitoneal injection of adriamycin （20 mg/kg）; carvedilol （2 mg/kg） was injected intraperitoneally after adriamycin. The equivalent volume of normal saline was used as control. The heart tissues were obtained at the 1, 3, 5, 10, and 15 days after drug administration. Reverse transcription polymerase chain reaction and immunohistochemistry were performed to assess the expression in bcl-2 and bax genes at different time course in mRNA and protein levels. Results （1）mRNA expression level of bcl-2 showed a tendency of decrease while a tendency of increase of bax level in adriamycin group. On contrary, carvedilol reversed the tendency by significantly higher bcl-2 expression and lower level of bax. （2） With immunohistochemistry technique, there is a significant difference for percentage of bax and bcl-2 positive cells between adriamycin group and adriamycincarvedilol group respectively （P＜0.05）. Conclusion The toxicity of adriamycin may be mediated by up-regulation of bax and down-regulation of bcl-2, carvedilol may promote the expression of bcl-2 and inhibit the expression of bax. These data provide clues to elucidate the protective mechanism of carvedilol.