ABSTRACT
Objectives To investigate the effects of Apelin 13 on myocardial metabolism in diabetic rats.Methods A total of 40 male Wister rats were randomly divided into normal control group (NC,n=8) and experimental group (n =32).Diabetic rats model were induced by high-sugar and high-fat diet combined with low-dose intraperitoneal injection of streptozotocin (STZ).The wellestablished 28 diabetic model rats were randomly divided into diabetic model group (DM,n=14) and apelin-13 treated group (n=14).In the Apelin-13 group,diabetic rats were administered Apelin-13 [0.1 μmol/(kg · d)]by intraperitoneal injection for 10 weeks,while the control group and diabetic model group were given an equal volume of 0.9％ NaCl.At the end of the 10th week,all rats were sacrificed after fasting glucose measurement.Levels of serum free fatty acids (FFA) and myocardial FFA were measured by ELISA.Expression of myocardial glucose transporter member 4 (GLUT4) were detected by immunohistochemistry.The mRNA expressions of myocardial PPARα,CD36 and CPT-1 were detected by real-time fluorescence quantitative PCR.Results Fasting blood glucose,serum FFA and myocardial FFA were significantly higher in DM group than in NC group (all P＜ 0.05).The level of plasma glucose and myocardial FFA were significant lower(P＞0.05) in Apelin-13 treated group than in DM group;but serum FFA was not significantly lower(P＜0.05).The mRNA expressions of PPARα,CD36,CPT-1 in cardiac myocyte were higher in DM group and Apelin-13 treated group than in control(P＜0.05),and lower in Apelin-13 treated group than in DM group(P＜ 0.05).The expression of myocardial GLUT4 was significantly lower in DM group(1.138±0.316)and in Apelin-13-treated group (4.631 ± 1.832) than in NC group(9.132 ± 2.156),(F=65.507,P＜ 0.05),and higher in Apelin-13-treated group than in DM group(P＜0.05).Conclusions Apelin-13 increases myocardial expression of GLUT4,improves utilization of FFA,and it can effectively reduce the expression of PPARα,CD36 and CPT-1.Therefore,it may play a vital role in the improvement of myocardial metabolism in diabetic rats.