Influence of AMPK/Akt/mTOR pathway mediated by ophiopogonin on autophagy of cardiac muscle cells in diabetic rats

Rao Xiaojuan; Wu Yumin; Wang Yan

doi:10.3969/j.issn.1674-4055.2018.11.22

Abstract：Objective To study the influence of ophiopogonin on autophagy of cardiac muscle cells and AMPK/Akt/mTOR pathway in rats with type 2 diabetes mellitus (T2DM). Methods Male C57BL/6J rats (n=58, aged 8 weeks) were randomly divided into control group (n=8) and diabetic model group (n=50). The control group was given basic diet, and diabetic model group was given high-fat diet and intraperitoneal injection of streptozotocin (STZ) for established T2DM model, and then divided into model group, rosiglitazone group and low-dose, mid-dose and high-dose ophiopogonin groups (each n=10). The rosiglitazone group was orally given rosiglitazone (2 mg/kg), and low-dose, mid-dose and high-dose ophiopogonin groups were given, respectively, ophiopogonin in different doses (50 mg/kg, 100 mg/kg, 200 mg/kg) once a day for 6 weeks. The serum indexes of peripheral blood, blood pressure (BP) and heart rate (HR) were determined. The heart function, ratio of peak E flow velocity to peak A flow velocity (E/A), E-wave deceleration time (EDT) and left ventricular isovolumic relaxation time (IVRT) were detected by using echocardiography. The changes of cardiac histopathology were observed after HE staining. The changes of autophagy related proteins-Beclin1 and LC3, AMP-activated protein kinase (AMPK), Akt, mTOR and their phosphorylate levels were detected by using Western blotting assay. Results ①The levels of fasting blood glucose (FBG) and fasting insulin (FINS), HR, triglyceride (TG) and total cholesterol (TC), and heart weight were significantly higher in model group than those in control group (P<0.05). After intervention of ophiopogonin or rosiglitazone, the levels of FBG, FINS, HR, TG and TC, and heart weight were significantly lower in rosiglitazone group and low-dose, mid-dose and high-dose ophiopogonin groups than those in model group (P<0.05), and there was a dose-dependent relationship in all ophiopogonin groups. ②Compared with control group, E/A decreased significantly, and EDT and IVRT were prolonged significantly in model group (P<0.05). Compared with model group, E/A increased significantly, and EDT and IVRT were shortened significantly in rosiglitazone group and all ophiopogonin groups (P<0.05). ③The ratio of Beclin1 to GAPDH and ratio of LC3-Ⅱto LC3-Ⅰ were significantly lower in model group than those in control group (P<0.05). The ratio of Beclin1 to GAPDH and ratio of LC3-Ⅱto LC3-Ⅰ were significantly higher in rosiglitazone group and all ophiopogonin groups than those in model group (P<0.05). ④Compared with control group, the ratio of p-AMPK to AMPK increased significantly, and ratio of p-Akt to Akt and ratio of p-mTOR to mTOR decreased significantly in model group (P<0.05). Compared with model group, the ratio of p-AMPK to AMPK decreased significantly (P<0.05), and ratio of p-Akt to Akt and ratio of p-mTOR to mTOR increased significantly (P<0.05) in rosiglitazone group and all ophiopogonin groups. Conclusion Ophiopogonin can promote autophagy of myocardial cells, and improve heart function in T2DM rats, and the mechanism may be related to activation of AMPK and inhibition of Akt/mTOR pathway.