LOCALIZATION OF ALDOSE REDUCTASE AND SORBITOL DEHYDROGENASE IN THE NERVOUS-SYSTEM OF NORMAL AND DIABETIC RATS

Intraneuronal accumulations of sorbitol and fructose were postulated to predispose the nervous system to the cerebral edema associated with the treatment of diabetic ketoacidosis. The enzymes of the pathway for the production of sorbitol and fructose, aldose reductase and sorbitol dehydrogenase, were localized histochemically in brain, spinal cord and sciatic nerve. Enzyme activity was limited to the choroidal epithelium, ependymal cells and pia mater in normal, 2 and 10 wk streptozotocin diabetic and vehicle-treated rats. Sorbitol dehydrogenase activity was located in blood vessels and perineurium of the sciatic nerve in these groups of rats. Comparison of diabetic and vehicle groups did not demonstrate any alteration in the activity of either enzyme in the CNS. There was a decrease in sorbitol dehydrogenase activity in the blood vessels in the sciatic nerve in 50% of the 10 wk diabetic rats.