Preliminary report: Leucine supplementation enhances glutamate dehydrogenase expression and restores glucose-induced insulin secretion in protein-malnourished rats
Abstract
Low-protein diet impairs insulin secretion in response to nutrients and may induce several metabolic disorders including diabetes, obesity, and cardiovascular disease. In the present study, the influence of leucine supplementation on glutamate dehydrogenase (GDH) expression and glucose-induced insulin secretion (GIIS) was investigated in malnourished rats. Four groups were fed with different diets for 12 weeks: a normal-protein diet (17%) without or with leucine supplementation or a low (6%)-protein diet without (LP) or with leucine supplementation (LPL). Leucine (1.5%) was supplied in the drinking water. Western blotting analysis revealed reduced GDH expression in LP, whereas LPL displayed improved GDH expression, similar to control. The GIIS and leucine-induced insulin release were also enhanced in LPL compared with LP and similar to those observed in rats fed a normal-protein diet without leucine supplementation. In addition, GDH allosteric activators produced an increased insulin secretion in LPL. These findings indicate that leucine supplementation was able to increase GDH expression leading to GIIS restoration, probably by improved leucine metabolic pathways.
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The authors declare that there is no conflict of interest that would prejudice the impartiality of this scientific work. Priscilla M.R. da Silva and Claudio C. Zoppi participated equally to manuscript drafting.
The experiments with animals are in adherence with the institutional State University of Campinas Committee for Ethics in Animal Experimentation.
PII: S0026-0495(09)00445-4
doi:10.1016/j.metabol.2009.10.014
© 2010 Elsevier Inc. All rights reserved.
