Involvement of Rictor/mTORC2/Akt/GLUT4 pathway in the regulation of energy metabolism in the gastric smooth muscle of diabetic rats

Abstract

Diabetes mellitus can be accompanied by a variety of complications. The purpose of the present study was to characterize the Rictor/mTOR complex 2 (mTORC2)/Akt/glucose transporter 4 (GLUT4) pathway and its effects on energy metabolism in the gastric smooth muscle of diabetic rats. Diabetes was induced in rats using streptozotocin and their phenotype was compared with untreated rats. The relationship between gastric motility and energy metabolism was analyzed by comparing the contraction and ATP metabolism of muscle strips. Western blotting was used to detect the expression of key proteins in the pathway. The diabetic rats demonstrated less frequent and less powerful gastric smooth muscle contractions. The concentrations of ADP, AMP, and ATP, and the energy charge in gastric smooth muscle changed in different periods of diabetes, and these changes were consistent with changes in mechanistic target of rapamycin (mTOR) protein content. The expression of the key intermediates in signal transduction in the Rictor/mTORC2/Akt/GLUT4 pathway also underwent significant changes. Rictor protein expression increased during the development of diabetes, but the activation of mTORC2 did not increase with the increase in Rictor expression. GLUT4 translocation is regulated by Akt and its expression change during the development of diabetes. These findings suggest that altered energy metabolism is present in gastric smooth muscle that is associated with changes in the Rictor/mTORC2/Akt/GLUT4 pathway. Rictor/mTORC2/Akt/GLUT4 pathway may be involved in the regulation of energy metabolism in the gastric smooth muscle of diabetic rats and the development of diabetic gastroparesis.