Aims: 

AMP-activated protein kinase (AMPK) is a cellular energy sensor functioning as a regulator of energy homeostasis in several peripheral tissues. In the skeletal muscle AMPK is involved in glucose metabolism by stimulating the translocation and gene expression of glucose transporter (GLUT-4). This insulin independent effect on muscle glucose uptake makes AMPK a promising target for the treatment of metabolic disorders such as obesity and type 2 diabetes. Seasonal animals provide interesting model in the research of body weight regulation and energy metabolism. The raccoon dog (Nyctereutes procynoides) is a wintering species with autumnal fattening and long fasting period during winter. In our present study we used farm bred raccoon dogs to evaluate the effect of fasting to the muscle energy metabolism.

Methods: 

Plasma insulin levels, phosphorylated AMPK (active form) and GLUT-4 protein expression from various hind limb muscles were determined after ten weeks of fasting.

Results: 

Fasting had no effect on AMPK activity. Reduction in GLUT-4 protein was observed in extensor digitorum longus. No alterations in plasma insulin concentration were detected.

Conclusion: 

These results indicate that even severe fasting does not affects raccoon dogs muscle AMPK activity. Furthermore, GLUT4 expression remains on steady level. Minor effects on pAMPK and GLUT-4 concentrations may indicate adaptations to tolerate long periods of food scarcity. Presumably raccoon dogs have effective regulatory system for preserving skeletal muscle function during winter time immobilization and food deprivation.