Effects of inhibition of glycation and oxidative stress on the development of diabetic nephropathy in rats.

We investigated whether aminoguanidine (AG), an inhibitor of advanced glycated end product formation, or probucol (PB), a free radical scavenger, could influence signs of glomerular and distal tubular function and morphological changes in kidneys of male Wistar rats after 6 months of streptozocin (STZ)-induced diabetes. Diabetic rats had a higher kidney weight/body weight ratio (P<.001), but neither AG nor PB influenced the increased ratio. Diabetes caused an increased urinary albumin excretion (P<.05), which was normalized by AG, but further exaggerated by PB (P<.001). Diabetes also caused an increase in the urinary excretion of Tamm-Horsfall protein (P<.001). Both AG and PB attenuated this increase (P<.05 for both). A few glomeruli displayed focal thickening of varying degrees. Silver staining disclosed the glomerulopathy to be intercapillary glomerulosclerosis. Rats on PB-enriched diet displayed less pronounced changes than untreated rats (P<.01), while AG had no effect. The results suggest that oxidative stress could be involved in the development of diabetic nephropathy.