Endoneurial fluid pressure in experimental models of diabetic neuropathy

The sorbitol pathway has been suggested as a biochemical mechanism for peripheral neuropathy in diabetes, due to accumulation of osmotically active polyols which cause endoneurial edema. The purpose of this study was to compare endoneurial fluid pressure (EFP) in the peripheral nerves of rats in three experimental models: streptozotocin diabetes, galactose neuropathy, and sucrose intoxication. Endoneurial fluid pressure was measured in 27 diabetic rats at intervals of 4 to 51 weeks after inoculation with streptozotocin and in ten control rats. Elevated fluid pressure was observed in only two diabetic animals, and there was no significant difference in mean EFP between test animals and controls. By contrast, elevated EFP was found in 9 of 11 rats who received a 68% sucrose diet for 48-51 weeks. The mean EFP in these animals was approximately twice normal, and sucrose intoxication thus appears to be a more effective model than streptozotocin diabetes for nerve edema associated with the sorbitol pathway.