Effects of 15-month aldose reductase inhibition with fidarestat on the experimental diabetic neuropathy in rats

We examined the effects of long-term treatment with an aldose reductase inh ibitor (ARI) fidarestat on functional, morphological and metabolic changes in the peripheral nerve of 15-month diabetic rats induced by streprozotocin (STZ). Slowed F-wave, motel nerve and sensory nerve conduction velocities were corrected dose-dependently in fidarestat-treated diabetic rats. Morpho metric analysis of myelinated fibers demonstrated that frequencies of abnor mal fibers such as paranodal demyelination and axonal degeneration were red uced to the extent of normal levels by fidarestat-treatment. Axonal atrophy , distorted axon circularity and reduction of myelin sheath thickness were also inhibited. These effects were associated with normalization of increas ed levels of sorbitol and fructose and decreased level of myo-inositol in t he peripheral nerve by fidarestat. Thus, the results demonstrated that long -term treatment with fidarestat substantially inhibited the functional and structural progression of diabetic neuropathy with inhibition of increased polyol pathway flux in diabetic rats. (C) 2000 Elsevier Science Ireland Ltd . All rights reserved.