QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Milanski, M. Articles by Latorraca, M. Q. Search for Related Content PubMed PubMed Citation Articles by Milanski, M. Articles by Latorraca, M. Q.

---

Nutrient-Gene Interactions

Low-Protein Diets Reduce PKA Expression in Islets from Pregnant Rats^1,2

Marciane Milanski, Vanessa Cristina Arantes^*, Fabiano Ferreira, Marise Auxiliadora de Barros Reis^*, Everardo Magalhães Carneiro^**, Antonio Carlos Boschero^**, Carla Beatriz Collares-Buzato and Márcia Queiroz Latorraca^*,3

Secretaria de Estado de Saúde, Mato Grosso, MT, Brazil; ^* Departamento de Alimentos e Nutrição, Faculdade de Nutrição, Universidade Federal de Mato Grosso, Cuiabá, MT, Brazil; Departamento de Fisiologia e Farmacologia, Universidade Federal de Pernambuco, Recife, PE, Brazil; ^** Departamento de Fisiologia e Biofísica and Departamento de Histologia e Embriologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brazil

³To whom correspondence should be addressed. E-mail: mqlator{at}terra.com.br.

We investigated the effect of protein restriction on insulin secretion and the expression of protein kinase (PK)A and PKC in islets from control and pregnant rats. Adult control nonpregnant (CN) and control pregnant (CP) rats were fed a normal-protein diet (17%), whereas low-protein nonpregnant (LPN) and low-protein pregnant (LPP) rats were fed a low-protein diet (6%) for 15 d. In the presence of 2.8 and 8.3 mmol glucose/L, insulin secretion by islets of CP rats was higher than that by islets of CN rats. Compared with the CN groups, insulin secretion by islets of LPN rats was lower with 8.3 but not with 2.8 mmol glucose/L. The insulin secretion by islets of LPP rats was higher than by LPN rats at both glucose concentrations. IBMX (1 mmol/L), a phosphodiesterase inhibitor, increased insulin secretion by islets from pregnant rats, and this effect was greater in islets of CP rats than in LPP rats. Forskolin (0.01–100 µmol/L), a stimulator of adenylyl cyclase, increased insulin secretion only in islets of CN and CP rats, with a higher 50% effective concentration in islets of CP rats compared with CN rats. The insulin secretion induced by phorbol 12-myristate 13-acetate (a stimulator of PKC) was higher in islets of LPN and LPP rats than in the respective controls, especially at 8.3 mmol glucose/L. PKA, but not PKC, expression was lower in islets of rats fed low protein than in the controls, regardless of the physiological status of the rats. All endocrine cells of the islets, including ß-cells, expressed the PKA isoform. The cytoplasmic distribution of this enzyme in ß-cells was not modified by pregnancy and/or protein restriction. In conclusion, our results indicate that the response of islets from rats fed low protein during pregnancy is similar to that of control rats, at least for physiologic glucose concentration. However, the decreased response to IBMX and forskolin indicates decreased production and/or sensitivity to cAMP; this was associated with a decrease in PKA expression, which may result in lower PKA activity.

KEY WORDS: • low-protein diet • insulin secretion • PKA • PKC • pregnancy • rats

This article has been cited by other articles:

				A. Chamson-Reig, S. M Thyssen, E. Arany, and D. J Hill Altered pancreatic morphology in the offspring of pregnant rats given reduced dietary protein is time and gender specific. J. Endocrinol., October 1, 2006; 191(1): 83 - 92. [Abstract] [Full Text] [PDF]