Impaired regeneration and no amelioration with aldose reductase inhibitor in crushed unmyelinated nerve fibers of diabetic rats

THE regenerative ability of unmyelinated nerve fibers (UNFs) in diabetes an d the effect of aldose reductase inhibitor (ARI) on it were ultrastructural ly evaluated after sciatic nerve crush in control and untreated and tolrest at-treated streptozocin-induced diabetic rats. The density and number of UN Fs were significantly increased in all groups at 5 weeks after the injury. The increase returned to the baseline level in control rats, but not in dia betic rats at 24 weeks. Although the axon size showed a marked decrease at 5 weeks and an incomplete recovery at 24 weeks in all groups, the recovery was significantly worse in diabetic than in control groups. Tolrestat did n ot have any effect on regeneration of UNFs in diabetes. These results sugge st impaired regeneration of UNFs after nerve crush injury in diabetes and l ess therapeutic effect of ARI on it. NeuroReport 10:2405-2409 (C) 1999 Lipp incott Williams & Wilkins.