Low protein diet confers resistance to the inhibitory effects of interleukin1 beta on insulin secretion in pancreatic islets

High protein content in the diet during childhood and adolescence has been associated to the onset insulin-dependent diabetes mellitus. We investigate d the effect of interleukin-1 beta (IL-I beta) on insulin secretion, glucos e metabolism, and nitrite formation by islets isolated from rats fed with n ormal protein (NP, 17%) or low protein (LP, 6%) after weaning. Pretreatment of islets with IL-1 beta for 1 h or 34 h inhibited the insulin secretion i nduced by glucose in both groups, but it was less marked in LP than in NP g roup. Islets from LP rats exhibited a decreased IL-1 beta -induced nitric o xide (NO) production, lower inhibition of D-[(UC)-C-14]-glucose oxidation t o (CO2)-C-14, and less pronounced effect of IL-1 beta on alpha -ketoisocapr oic acid-induced insulin secretion than NP islets. However, when the islets were stimulated by high concentrations of K+ the inhibitory effect of IL-1 beta on insulin secretion was not different between groups. In conclusion, protein restriction protects beta -cells of the deleterious effect of IL-1 beta, apparently, by decreasing NO production. The lower NO generation in islets from protein deprived rats may be due to increased free fatty acids oxidation and consequent alteration in Ca2+ homeostasis. (C) 2001 Elsevier Science Inc. All rights reserved.