부산대학교 도서관

We investigated the insulin release induced by glucose, the [Ca.sup.2+] oscillatory pattern, and the cyclic AMP (cAMP)/protein kinase A (PKA) and phospholipase C (PLC)/protein kinase C (PKC) pathways in islets from adult rats that were reared under diets with 17% protein (C) or 6% protein (LP) during gestation, suckling, and after weaning and in rats receiving diets with 6% protein during gestation and 17% protein after birth (R). First-phase glucose-induced insulin secretion was reduced in LP and R islets, and the second phase was partially restored in the R group. Glucose stimulation did not modify intracellular [Ca.sup.2+] concentration, but it reduced the [Ca.sup.2+] oscillatory frequency in the R group compared with the C group. Intracellular cAMP concentration was higher and PKA-Ca expression was lower in the R and LP groups compared with the C group. The PKC[alpha] content in islets from R rats was lower than that in C and LP rats. Thus, nutritional recovery from a low-protein diet during fetal life did not repair the kinetics of insulin release, impaired [Ca.sup.2+] handling, and altered the cAMP/PKA and PLC/PKC pathways.Key words: insulin secretion, [Ca.sup.2+] oscillation, protein kinase A, protein kinase C, nutritional recovery.Dans cette etude, on examine la liberation d'insuline induite par le glucose, le mode oscillatoire du calcium (<< [Ca.sup.2+]>>) et les voies adenosine monophosphate cyclique (<>)/proteine kinase A (<>) et phospholipase C (<>)/proteine kinase C (<>) dans les Hots de rats adultes soumis durant leur elevage a un regime comprenant 17 % (<< C>>) ou 6 % (<>) de proteines, et ce, durant la gestation, l'allaitement et apres le sevrage; l'etude soumet aussi des rats a un regime comprenant 6 % de proteines durant la gestation puis a un regime comprenant 17 % de proteines apres la naissance (<>). Durant la premiere phase, la secretion de l'insuline causee par le glucose est diminuee dans les llots des groupes LP et R, mais elle revient partiellement a la normale durant la deuxieme phase dans le groupe R. La stimulation du glucose ne modifie pas la concentration intracellulaire de [Ca.sup.2+], mais diminue la frequence d'oscillation de [Ca.sup.2+] dans le groupe R comparativement au groupe C. La concentration intracellulaire de cAMP est plus elevee et l'expression de PKA-Ca est plus faible dans les groupes R et LP comparativement au groupe C. Le contenu des llots en PKC[alpha] dans le groupe R est plus faible que dans les groupes C et LP. En consequence, la recuperation sur le plan nutritionnel d'un faible apport proteique durant la periode fetale ne restaure pas la cinetique de la liberation de l'insuline, deregle le deplacement du [Ca.sup.2+] et modifie les voies de cAMP/PKA et PLC/PKC. [Traduit par la Redaction]Mots-cles: secretion d'insuline, oscillation du [Ca.sup.2+], proteine kinase A, proteine kinase C, recuperation nutritionnelle.
IntroductionAlterations in the maternal metabolic milieu during pregnancy influence the development and functional maturation of beta (P)cells of the offspring. The growth of p-cells and the secretion of insulin during [...]