A low-protein diet during pregnancy alters glucose metabolism and insulin secretion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)In pancreatic islets, glucose metabolism is a key process for insulin secretion, and pregnancy requires an increase in insulin secretion to compensate for the typical insulin resistance at the end of this period. Because a low-protein diet decreases insulin secretion, this type of diet could impair glucose homeostasis, leading to gestational diabetes. In pancreatic islets, we investigated GLUT2, glucokinase and hexokinase expression patterns as well as glucose uptake, utilization and oxidation rates. Adult control non-pregnant (CNP) and control pregnant (CP) rats were fed a normal protein diet (17%), whereas low-protein non-pregnant (LPNP) and low-protein pregnant (LPP) rats were fed a low-protein diet (6%) from days 1 to 15 of pregnancy. The insulin secretion in 2.8?mmol l-1 of glucose was higher in islets from LPP rats than that in islets from CP, CNP and LPNP rats. Maximal insulin release was obtained at 8.3 and 16.7?mmol l-1 of glucose in LPP and CP groups, respectively. The glucose doseresponse curve from LPNP group was shifted to the right in relation to the CNP group. In the CP group, the concentrationresponse curve to glucose was shifted to the left compared with the CNP group. The LPP groups exhibited an inverted U-shape doseresponse curve. The alterations in the GLUT2, glucokinase and hexokinase expression patterns neither impaired glucose metabolism nor correlated with glucose islet sensitivity, suggesting that beta-cell sensitivity to glucose requires secondary events other than the observed metabolic/molecular events. Copyright (c) 2011 John Wiley & Sons, Ltd.302114121Fundacao de Amparo a Pesquisa do Estado de Mato Grosso [0786/2006]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundacao de Amparo a Pesquisa do Estado de Mato Grosso [0786/2006]CNPq [305155/2004-0

Soybean diet alters the insulin-signaling pathway in the liver of rats recovering from early-life malnutrition

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Objective: We investigated if alterations in the insulin-signaling pathway could contribute to reduced hepatic glycogen levels in adult rats subjected to a protein deficiency during intrauterine life and lactation and reared through to recovery on a soybean diet Methods: Rats from mothers led with 17% or 6% protein (casein) during pregnancy and lactation were maintained with a 17% casein diet (offspring born to and suckled by mothers fed a control diet and subsequently fed the same diet after weaning [CC group] and offspring born to and suckled by mothers fed a control diet and subsequently fed a soybean flour diet with 17% protein after weaning [CS group]), a soybean diet (offspring of mothers fed a low-protein diet and a control diet after weaning [LC group] and offspring of mothers fed a low-protein diet and fed a soybean Hour diet containing 17% protein after weaning [LS group]). or a 6% casein diet (offspring of mothers fed a low-protein diet and subsequently fed the same diet after weaning [LL group]) from weaning until 90 d of life Results: A soybean diet did not modify basal serum glucose and glucagon concentrations, but raised basal serum insulin and consequently increased the serum insulin/glucose ratio Insulin receptor and insulin receptor substrate-1 levels were lower in rats fed a soybean diet compared with those maintained with a casein diet In the LS group. the p85 levels were higher Man in the LC group, whereas in CS rats its expression was lower than in CC mats The expression of p110 was lower in the CS group compared with the CC group and similar in the LS and LC groups Insulin receptor substrate-1 phosphorylation was similar in the LS. LC. and CS groups and lower compared with the CC group The insulin receptor substrate-1-p85/phosphatidylinositol 3-kinase association was lower in LS than in LC rats and in CS than in CC rats Akt phosphorylation was lower in the CS and LS groups than in the CC and LC groups Conclusion: Adult rats maintained with a soybean diet exhibited insulin resistance due, at least in part. to alterations in the early steps of the insulin signal transduction pathway (C) 2010 Elsevier Inc All rights reserved264441448FAPEMAT [175/04]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FINEP/PRONEX [134/97]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPEMAT [175/04]CNPq [479138/2003-6]FINEP/PRONEX [134/97