Low protein diet confers resistance to the inhibitory effects of interleukin 1beta 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 investigated the effect of interleukin-1beta (IL-1beta) on insulin secretion, glucose metabolism, and nitrite formation by islets isolated from rats fed with normal protein (NP, 17%) or low protein (LP, 6%) after weaning. Pretreatment of islets with IL-1beta for 1 h or 24 h inhibited the insulin secretion induced by glucose in both groups, but it was less marked in LP than in NP group. Islets from LP rats exhibited a decreased IL-1beta-induced nitric oxide (NO) production, lower inhibition of D-[U(14)C]-glucose oxidation to (14)CO(2) and less pronounced effect of IL-1beta on alpha-ketoisocaproic acid-induced insulin secretion than NP islets. However, when the islets were stimulated by high concentrations of K(+) the inhibitory effect of IL-1beta on insulin secretion was not different between groups. In conclusion, protein restriction protects beta-cells of the deleterious effect of IL-1beta, 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 Ca(2+) homeostasis.
Vieira
E C.
EC
Departamento de Fisiologia e Biofísica, Instituto de Biologia, Universidade Estadual de Campinas UNICAMP, CP6109, Campinas, 13083-970, São Paulo, Brazil
Carneiro
E M.
EM
Latorraca
M Q.
MQ
Delguingaro-Augusto
V
V
Amaral
M E.C.
ME
Bosqueiro
J R.
JR
Boschero
A C.
AC