Effect of Dietary Fish Oil on Insulin Sensitivity and Metabolic Fate of Glucose in the Skeletal Muscle of Normal Rats

The aim of this work was to study the effect of the administration of cod liver oil on the non-oxidative and oxidative fate of glucose metabolism in the skeletal muscle of normal rats. To achieve this goal, the gastrocnemius was examined regarding glucose oxidation, glycogen synthase activity and glycogen storage both at baseline and during euglycemic hyperinsulinemic clamping. The results show that dietary fish oil decreases plasma insulin levels without alteration in glucose homeostasis (at baseline). In addition, the observed enhancement in whole body glucose utilization during clamping suggests an increased peripheral insulin sensitivity. Furthermore, under insulin-stimulated glucose disposal, an enhancement in the glycolytic pathway (increased levels of muscle glucose-6-phosphate and plasma lactate) rather than changes in the oxidation (pyruvate dehydrogenase complex) and storage components of glucose metabolism was observed in the skeletal muscle of rats fed dietary fish oil. These results coupled with the hypolipidemic effects of fish oil may have implications for the prevention and/or management of some pathological states manifested by insulin resistance with or without dyslipidemia.