Abstract:

Objective To discuss the improvement effect of baicalin on the myocardial hypertrophy and apoptosis induced by abdominal aorta ligation of the rats， and to clarify the potential mechanism. Methods The SD rats were randomly divided into control group， model group， low dose of baicalin （50 mg·kg^－1） group， and high dose of baicalin （100 mg·kg^－1） group.The rat model of myocardial hypertrophy was established by abdominal aorta ligation method. The rats in low and high doses of baicalin groups were given 50 and 100 mg·kg^－1 baicalin.After six weeks， the left ventricular ejection fraction （LVEF）， left ventricular posterior wall thickness at end-diastolic （LVPWd）， left ventricular posterior wall thickness at end-systolic （LVPWs），interventricular septal thickness at end-diastolic （IVSd） and interventricular septal thickness at end-systolic （IVSs） of rats in various groups were measured by echocardiography； the heart weight index（HWI） and left ventricular weight index （LVWI） of rats in various groups were calculated； HE staining was used to observe the pathomorphology of myocardium tissue of the rats in various groups； the serum levels of interleukin-8 （IL-8），interleukin-1β （IL-1β），tumor necrosis factor-α （TNF-α）， and interleukin-6 （IL-6） of the rats in various groups were detected by enzyme-linked immunosorbnent assay（ELISA） method；the expression levels of B-cell lymphoma-2 （Bcl-2）， Bcl-2 associated X protein （Bax），apoptosis-inducing factor （AIF），and calpain-1 proteins in myocardium tissue of the rats in various groups were detected by Western blotting method. Results Compared with control group， the LVEF of the rats in model group was significantly decreased（P<0.01），and the LVPWd， LVPWs， IVSd， IVSs， HWI， and LVWI were significantly increased（P<0.01）， the myocardium tissue were disordered arrangement； the serum levels of TNF-α，IL-6，IL-8， and IL-1β were increased（P<0.01）； the expression levels of Bcl-2 protein in myocardium tissue of the rats were decreased（P<0.01）， while the expression levels of Bax， AIF， and calpain-1 proteins were increased（P<0.01），and the ratio of Bax/Bcl-2 was increased（P<0.01）. Compared with model group， the LVEF of the rats in low and high doses of baicalin groups was increased（P<0.01），and the LVPWd， LVPWs， IVSd， IVSs， HWI， and LVWI were decreased（P<0.05 or P<0.01）；the cardiomyocytes in myocardium tissue were arranged in order；the serum levels of TNF-α，IL-6，IL-8， and IL-1β were decreased（P<0.05）；the expression levels of Bcl-2 protein in myocardium tissue of the rats were increased（P<0.01）， while the expression levels of Bax， AIF， and calpain-1 proteins were decreased（P<0.05）， and the ratios of Bax/Bcl-2 were decreased（P<0.05 or P<0.01）. Compared with low dose of baicalin group， the LVPWS and HWI of the rats in high dose of baicalin group were decreased（P<0.05）；the levels of TNF-α，IL-6，IL-8，and IL-1β in serum and the expression level of Bax protein were decreased（P>0.05），but there were no statistically significant differences in the other indexes（P>0.05）. Conclusion Baicalin can improve the myocardial hypertrophy and inhibit the inflammation and apoptosis induced by abdominal aorta ligation of the rats， and its mechanism may be related to the regulation of calpain-1/AIF signaling pathway.

Key words: Baicalin, Apoptosis, Calpain-1, Apoptosis-inducing factor, Myocardial hypertrophy