Combined effect of probucol and insulin on renal damage in diabetic rats fed a high cholesterol diet.

We investigated the effects of long-term treatment with probucol, a hypolipidemic agent with antioxidative action, insulin, or their combination on renal damage in streptozotocin-induced diabetic rats fed a high cholesterol diet. Increases in urinary albumin and lipid peroxide excretions were observed in these diabetic rats, when both urinary parameters were measured at 8 and 15 weeks after streptozotocin administration. Daily treatment with probucol, insulin, or their combination markedly suppressed the increase in the 24 h urinary albumin and lipid peroxide excretions. Furthermore, glycogen degeneration of distal tubules, fatty degeneration of glomerular endothelium, and hypertrophy of glomeruli and mesangium were observed in the kidneys of the diabetic animals, when histopathological evaluation was performed at 4, 8 and 15 weeks (glomerular and mesangial hypertrophy was observed only at 15 weeks). Combined probucol and insulin treatment was the most effective in suppressing these renal histopathological changes. These results indicate that combined treatment with probucol and insulin is useful in preventing the progression of renal damage in diabetic rats. The possible mechanisms for the preventive effect of this combined treatment will be discussed.