Involvement of <i>Pgc-1α</i> in the skeletal muscle on glucose uptake via the peripheral sympathetic nervous system in rats

It has been suggested that sympathetic nerve activity is involved with not only blood pressure control but also enhancement of peripheral glucose uptake. To evaluate the effects of peripheral sympathetic activation on glucose uptake and skeletal muscle mRNA expression involved with energy metabolism, in the present study, we detected sympathetic nervous signal with a microelectrode in the unilateral sciatic nerve under anesthetic condition in normal and high-fat diet-fed (HFD) rats, and applied electrical microstimulation (MS) via the microelectrode. Glucose uptake was assessed as glucose infusion rate (GIR) during the hyperinsulinemic-euglycemic clamp. The MS significantly increased the GIR in both groups (P<0.01) whereas we observed no significant change in plasma insulin level. Furthermore, the GIR in HFD group was lower than that in the normal group. As a result of the MS for 60 min, in the normal group, Pgc-1α expressions in the bilateral soleus and extensor digitorum longus (EDL) tended to be elevated while Glut4 expression in the bilateral EDL was significantly suppressed (P<0.05). In contrast, these changes were not seen in the HFD group. These results suggest that the MS enhances non-insulin-mediated glucose uptake, and the effects may be mediated by several pathways including Pgc-1α in the soleus but not in the EDL.