胸腺素β4对急性心肌梗死大鼠心肌磷酸化蛋白激酶表达及纤维化的影响

Effects of thymosin β4 on myocardial fibrosis and expression of p-Akt in infarct myocardimn in rats

目的：探讨胸腺素β4（Tβ4）对心肌梗死大鼠心肌磷酸化蛋白激酶（p-Akt）及心肌纤维化的影响。方法：SD大鼠随机分为对照组、Tβ4低剂量组和高剂量组，结扎大鼠左冠状动脉前降支, 造成永久心梗模型。对照组予PBS，低剂量组和高剂量组予Tβ4腹腔注射，1、 5、 10d取材，行胶原纤维组织化学显色和pAkt免疫组织化学显色。结果：各组胶原纤维面积无明显差异；10d pAkt阳性细胞平均光密度高、低剂量组均高于对照组，高、低剂量组10d pAkt阳性细胞平均光密度均高于5d和1d 。结论：Tβ4对早期心梗的心肌纤维化影响不明显；Tβ4能促进急性心梗心肌的Akt磷酸化，上调p-Akt的表达，可能激活下游心肌保护因子从而改善心功能。

Objective： To study the effects of thyrnosinβ4（Tβ4） on myocardial fibrosis and expression of p-Akt in infarct myocardium in rats. Methods： After been ligated with left anterior descending coronary artery, the Sprague-Dawley rats were randomly treated with daily intraperitoneal PBS （control）, intraperitoneal Tβ4 at the concentration of 0. 08 μg/100 g （low dose） or 0. 8 μg/100 g （high dose）. At day 1, 5 and 10, the hearts of each group were removed to examine change of myocardial fibrosis based on area of fibrosis using Masson stain, and expression of p-Akt using immunohistochemistry. Results： No significant differences were detected in the area of fibrosis between control and two experimental groups. The average op- tical densities of p-Akt positive products were higher in two doses Tβ4 treated groups, and increased with prolonged treatment. Conclusion： Tβ4 may have no effect on myocardial fibrosis in early myocardial infarction. Our results suggest that Tβ4 can improve cardiac function via promoting the Akt phosphorylation and stimulating downstream cascade of myocyte survival factors.