Enhanced in situ expression of aldose reductase in peripheral nerve and renal glomeruli in diabetic patients

To explore the relationships between polyol pathway-related enzymes and pat hologic features, we examined the immunohistochemical expression of aldose reductase (AR) and sorbitol dehydrogenase (SDH) in the peripheral nerve and kidney tissues collected postmortem from diabetic patients and compared it with those from non-diabetic patients. Tissue AR protein concentrations we re also quantified. In non-diabetic patients, AR distributed in pericytes, smooth muscle cells of endo-and epi-neurial microvessels. Schwann cells in the sciatic nerve, and tubular cells of the renal medulla. By contrast, pos itive SDH reactions were observed in tubular cells of the renal cortex but were faint in the sciatic nerve. Diabetic patients frequently showed dense AR expressions in the sciatic nerve. In nephropathic diabetic patients, the glomerular mesangial area showed diffuse positive reactions for AR. The se verity of structural changes in glomeruli correlated with the intensity of immunoreactive AR (r(2)=0.626. P <0.01). AR contents in the renal cortex an d sciatic nerve from diabetic patients were 1.5- and 1.8-fold greater than those from non-diabetic patients, respectively (P <0.05 for both). These fi ndings are the first to demonstrate enhanced AR expressions in peripheral n erve and renal glomeruli in diabetic patients and its relevance to the char acteristic pathology.