Aim: the liver is essential in maintaining and regulating glucose homeostasis during exercise. Interleukin 6(IL-6) has been shown to be secreted from skeletal muscle during exercise and has been suggested to signal to the liver. Therefore, the aim was to investigate the role of skeletal muscle IL-6 on hepatic glucose regulation and substrate choice during prolonged exercise. Methods: twelve weeks old skeletal muscle specific IL-6 knockout(IL-6 MKO) mice and littermate lox/lox(Control) mice were either rested(Rest) or completed a single bout of exercise for 10min, 60 min or 120 min and the liver was quickly obtained. Results: hepatic IL-6 mRNA was higher at 60 min of exercise and hepatic signal transducer and activator of transcription 3 was higher at 120 min of exercise than at Rest in both genotypes. Hepatic glycogen was higher in IL-6 MKO than Control at Rest, but decreased similarly during exercise in the two genotypes, and hepatic glucose content was lower in IL-6 MKO than Control at 120 min of exercise. Hepatic phosphoenolpyruvate carboxykinase mRNA and protein increased in both genotypes at 120 min of exercise, while hepatic glucose 6 phosphatase protein remained unchanged. Furthermore, IL-6 MKO mice had higher hepatic pyruvate dehydrogenase(PDH)Ser232 and PDHSer300 phosphorylation than Control at Rest. Conclusion: hepatic gluconeogenic capacity is increased during prolonged exercise independent of muscle IL-6. Skeletal muscle IL-6 influences hepatic substrate regulation at rest and hepatic glucose metabolism during prolonged exercise seemingly independent of IL-6 signaling in the liver.
- glucose metabolism
- skeletal muscle IL-6
- substrate choice
- Copyright © 2017, American Journal of Physiology-Regulatory, Integrative and Comparative Physiology