Effects of Acute Aerobic Exercise on Skeletal Muscle and Liver Glucose Metabolism in Male Rodents with Type 1 Diabetes.

Abstract

Aerobic exercise (AE) is associated with a significant hypoglycemia risk in individuals with type 1 diabetes mellitus (T1DM). However, the mechanisms in the liver and skeletal muscle governing exercise-induced hypoglycemia in T1DM are poorly understood. This study examined the effects of a 60-minute bout of AE on hepatic and muscle glucose metabolism in T1DM rats. Nineteen male Sprague-Dawley rats were divided into sedentary (SC; n=5) and T1DM (DSC; n=14) groups. T1DM rats were subcategorized into pre-exercise (DPRE; n=6) and post-exercise (DPOST; n=8). DPOST were sacrificed immediately after 60-minute of AE. Results demonstrate that DPOST animals experienced reductions in BG following 30 and 60 minutes of AE compared to pre-exercise. Both DPRE and DPOST animals exhibited lower hepatic glycogen content, while muscle glycogen did not differ, suggesting impaired glycogenolysis in T1DM. Hepatic glycogen-6-phosphatase content, and muscle and hepatic protein kinase B phosphorylation were significantly greater in DPOST animals, suggesting elevated gluconeogenesis and insulin stimulation during exercise. Glycogen phosphorylase activity did not differ between groups. These data suggest that drops in BG during AE in T1DM were due to lower glycogen levels in the liver and muscle and a lack of muscle glycogen utilization; leading to a reliance on gluconeogenesis and BG.