The in vitro effect of corticosterone on insulin binding and glucose metabolism in mouse skeletal muscles.

We studied the in vitro effect of corticosterone on insulin binding, uptake of 2-deoxy-D-glucose, glycolysis, and glycogenesis in the soleus and extensor digitorum longus (EDL) of Swiss-Webster mice. In each experiment, one muscle (soleus/EDL) was incubated with corticosterone (0.1, 1, 50, and 100 micrograms/mL) and the respective contralateral muscle was incubated without corticosterone, but at the same insulin and pH levels. Corticosterone did not affect insulin binding in both muscles. However, corticosterone decreased the uptake of 2-deoxy-D-glucose and the rate of glycolysis and glycogenesis in both muscles when the dose was pharmacologic (50 and 100 micrograms/mL), but not when it was physiologic (0.1 and 1 microgram/mL). For glycolysis and glycogenesis, the suppression was greater in the EDL when compared with the soleus. This suppression was seen in both basal and insulin-stimulated conditions. In this in vitro system, where the experimental muscle is not exposed to prior hyperinsulinemia as in the in vivo model, corticosterone, at pharmacologic doses, affects postreceptor events without altering the insulin binding in the skeletal muscle.