THE EFFECTS OF ACETYL-L-CARNITINE AND SORBINIL ON PERIPHERAL-NERVE STRUCTURE, CHEMISTRY, AND FUNCTION IN EXPERIMENTAL DIABETES

Nerve conduction velocity (NCV) increased with age in nondiabetic male Wistar rats for the first 26 weeks of life. The NCV of animals made h yperglycemic at age 6 weeks by administration of streptozotocin (STZ) also increases, but at a slower rate. Animals with 4 weeks of hypergly cemia and reduced NCV treated with an aldose reductase inhibitor (sorb inil) or a short chain acyl-carnitine (acetyl-L-carnitine [ALC]) daily for 16 weeks showed an improvement in NCV. Morphometric studies of ti bial nerves collected from animals after 20 weeks of hyperglycemia (ag e 26 weeks) showed a consistent reduction in the width of the myelin s heath and little change in axon area. The number of large myelinated f ibers (>6.5 mu m) found in nerves collected from hyperglycemic animals was less than the number found in nondiabetic animals. Treatment of h yperglycemic rats with either sorbinil or ALC was associated with incr eased NCV, myelin width, and large myelinated fibers. The apparent met abolic effect of these agents was similar for fatty acid metabolism, b ut different for polyol pathway activity. We conclude that in animals hyperglycemic long enough to slow NCV, sorbinil and/or ALC treatment r educes the functional, structural, and biochemical changes associated with hygerglycemia that occur in the myelin sheath. Copyright of 1996 by W.B. Saunders Company