Physical exercise increases the expression of TNFα and GLUT 1 in muscle tissue of diabetes prone Psammomys obesus

Introduction: Tumor necrosis factor-α (TNFα) is a major mediator of insulin resistance. On the other hand, it has been suggested that TNFα may facilitate glucose uptake through GLUT 1 expression. We recently found that physical exercise prevented the progression to type 2 diabetes mellitus in diabetes prone Psammomys obesus (sand rat). Aim: The aim of the present study was to characterize the influence of physical exercise on the expression of TNFα, its receptor R1 and GLUT 1 in muscle tissue of this animal model. Methods: Animals were assigned for 4 weeks to four groups: high-energy diet (HC), high-energy diet and exercise (HE), low-energy diet (LC), low-energy diet and exercise (LE). TNFα, R1 and GLUT 1 expression were analyzed using Western blot technique. Results: None of the animals in the HE group became diabetic while all the animals in the HC group became diabetic. TNFα, its receptor (R1) and GLUT 1 expressions were significantly higher in the two exercising groups (LE and HE) and significantly lower in the HC group compared to the control LC group. Conclusions: Physical exercise augments the expression of TNFα, its receptor R1 and the glucose transporter GLUT 1 in muscle tissue. We suggest that this mechanism may improve glucose uptake through pathways parallel and unrelated to insulin signaling that may include MAPK and/or NO. These biochemical processes contribute to the beneficial effects of physical exercise on the prevention of type 2 diabetes mellitus.