Essential fatty acids prevent slowed nerve conduction in streptozotocin diabetic rats

Rats were given streptozotocin to induce insulin-dependent diabetes or citrate buffer alone in two experiments. Initially, the effect of 5 wks of dietary gamma-linolenic acid (GLA) plus eicosapentaenoic acid (EPA) on cutaneous nerve conduction velocity (CV) was examined. CV was determined by direct stimulation and recording from saphenous nerve under urethane anesthesia. Secondly, a 5 weeks study of supplementing the diet with GLA, GLA and EPA, or hydrogenated coconut oil (HC) was done. In addition, motor nerve CV was determined by directly stimulating sciatic nerve and recording from gastrocnemius muscle. The acute diabetes led to weight loss, and elevated blood glucose and glycosylated hemoglobin levels. Essential fatty acid (EFA) supplementation had no effect on any of these measures of severity of diabetes. In diabetic rats without EFA supplementation, CV of the myelinated fibers fell by 19-21%, while those receiving both GLA and EPA had normal CV. In diabetic rats receiving GLA alone, CV fell by 5-7%, which was significantly less than those without EFA supplementation (p less than 0.01 for cutaneous, and p less than 0.001 for motor nerves).