Nerve function in experimental diabetes in rats: effects of electrical stimulation

The effects of unilateral electrical stimulation of the peroneal sciatic nerve branch were studied in streptozocin-diabetic rats of 12-wk duration. Stimulation was carried out over 7 days (10 Hz, 8 h/day) with chronically implanted electrodes. Compared with controls, there was a 25% conduction velocity (CV) deficit for the peroneal nerve supplying tibialis anterior muscle in the unstimulated leg, which was corrected by stimulation. For tibial fibers supplying soleus muscle, a similar diabetic CV deficit (20%) was normalized by stimulation, although soleus axons were not directly activated. In saphenous nerve, which has a functionally separate vascular supply, peroneal stimulation was ineffective. In anesthetized diabetic rats, stimulation caused an 18% reduction in tibialis anterior CV after 4 h. However, serial measurements showed progressive normalization of CV over 4 days of stimulation. On termination, CV returned to diabetic levels over 36–60 h. Sciatic nerve showed a 70% increase in resistance to hypoxic conduction failure with diabetes, which was halved by chronic stimulation. Acute experiments demonstrated that peroneal stimulation increased sciatic vascular conductance by 60%. We conclude that stimulation causes activity-related improvements in diabetic nerve blood flow and metabolism.