title: 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.
authors.affiliation: Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology, State University of Campinas (UNICAMP), Caixa Postal 6109, Campinas, SP CEP, 13083-970, Brazil.
authors.forename: Priscilla Muniz Ribeiro
authors.initials: PM
authors.lastname: da Silva
authors.forename: Claudio Cesar
authors.initials: CC
authors.lastname: Zoppi
authors.forename: Eliane
authors.initials: E
authors.lastname: Filiputti
authors.forename: Leonardo Reis
authors.initials: LR
authors.lastname: Silveira
authors.forename: Ivan
authors.initials: I
authors.lastname: Quesada
authors.forename: Antonio Carlos
authors.initials: AC
authors.lastname: Boschero
authors.forename: Everardo Magalhães
authors.initials: EM
authors.lastname: Carneiro
mesh_terms: D000818:Animals; D015153:Blotting, Western; D005947:Glucose / Q000494:pharmacology*; D005969:Glutamate Dehydrogenase / Q000096:biosynthesis* / Q000235:genetics; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D007930:Leucine / Q000627:therapeutic use*; D008297:Male; D011502:Protein-Energy Malnutrition / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism*; D051381:Rats
chemical_list: D007328:Insulin; D005969:Glutamate Dehydrogenase; D007930:Leucine; D005947:Glucose