Effects of Apelin-13 on expression levels of glucose and lipid metabolism-related genes in the liver and skeletal muscle of diabetic rats

Abstract

Objective To investigate the effects of exogenous Apelin-13 on the expression of glucose and fatty acid metabolism-related genes in the liver and skeletal muscle of diabetic rats. Methods Forty male Wister rats were randomly divided into a control group (n=8) and an experimental group (n=32). In the experimental group, a rat model of type 2 diabetes mellitus was established by a high-glucose and high-fat diet and intraperitoneal injection of streptozotocin (STZ). The diabetic rats were randomized into a diabetic model group and an Apelin-13 treatment group with 14 rats in each group.Rats in the Apelin-13 treatment group were intraperitoneally injected with 0.1 μmol·kg·d-1 Apelin-13 for 10 weeks, while the control group and the diabetic model group were injected with an equal volume of 0.9% NaCl solution for 10 weeks.At the end of the 10 week treatment, fasting blood glucose values in each group were measured.Levels of mRNA expression of glucose-6-phosphate (G-6-P), phosphoenolpyruvate carboxykinase (PEPCK), peroxisome proliferator-activated receptor alpha (PPAR-α), acy1-CoA synthetase long-chain family member1 (ACSL1), and carnitine palmitoyltransferase1 (CPT1) in the liver and levels of mRNA expression of PPAR-α and glucose transporter type 4 (GLUT4) in skeletal muscle were detected by real-time fluorescence quantitative polymerase chain reaction (PCR). Results Levels of mRNA expression of liver PPAR-α, liver ACSL1, liver CPT1, and GLUT4 in skeletal muscle were lower in the diabetic model group (0.309±0.073, 0.508±0.056, 0.389±0.118 and 0.289±0.066, respectively) than in the control group (0.971±0.028, 0.990±0.015, 0.987±0.015 and 0.994±0.009, respectively) (all P 0.05). Conclusions Apelin-13 increases the expression of the PPAR, ACSL1, and CPT1 genes in the liver and, to a certain extent, improves fatty acid oxidation metabolism in the liver in type 2 diabetic rats.It also increases the expression of the G-6-P and PEPCK genes, promotes gluconeogenesis in the liver, and may be related to the development of type 2 diabetes.In skeletal muscle, Apelin-13 increases GLUT4 gene expression, moderately improves skeletal muscle metabolism and may play a role in the regulation of oxidative stress. Key words: Diabetes mellitus; Carbohydrate metabolism; Lipid metabolism; Apelin-13