Protective effect of nicotinamide against nephropathy in diabetic rats.

Nicotinamide was given for 6 months to rats with streptozotocin induced diabetes. Presence of glomerular depositions (mesangial distribution) of IgG was evaluated with immunofluorescence technique. The immunofluorescence staining of the nicotinamide-treated diabetic rats was significantly less pronounced than that of the untreated diabetic rats. Normal age matched controls showed no such staining. The results indicate that nicotinamide retarded the development of the diabetic nephropathy. The findings might be explained by a normalizing effect of nicotinamide on a disturbed tryptophan and/or nicotinamide adenine dinucleotide metabolism. A metabolic hypothesis is formulated, which is consistent with the "glucose overutilization" theory.