Effects of leucine supplementation and resistance exercise on dexamethasone-induced muscle atrophy and insulin resistance in rats

Effects of leucine supplementation and resistance exercise on dexamethasone-induced muscle atrophy and insulin resistance in rats

Author Nicastro, Humberto Google Scholar
Zanchi, Nelo Eidy Google Scholar
Luz, Claudia Ribeiro da Google Scholar
Moraes, Wilson Max Almeida Monteiro de Google Scholar
Ramona, Pamella Google Scholar
Siqueira Filho, Mario Alves de Google Scholar
Chaves, Daniela Fojo Seixas Google Scholar
Medeiros, Alessandra Autor UNIFESP Google Scholar
Brum, Patricia Chakur Google Scholar
Dardevet, Dominique Google Scholar
Lancha Junior, Antonio Herbert Google Scholar
Institution Universidade de São Paulo (USP)
Universidade Federal de São Paulo (UNIFESP)
Clermont Univ
INRA
Abstract Objective: We aimed to evaluate the effects of resistance exercise (RE) and leucine (LEU) supplementation on dexamethasone (DEXA)-induced muscle atrophy and insulin resistance.Methods: Male Wistar rats were randomly divided into DEXA(DEX), DEXA + RE (DEX-RE), DEXA + LEU (DEX-LEU), and DEXA + RE + LEU (DEX-RE-LEU) groups. Each group received DEXA 5 mg . kg(-1) . d(-1) for 7 d from drinking water and were pair-fed to the DEX group; LEU-supplemented groups received 0.135 g . kg(-1) . d(-1) through gavage for 7 d; the RE protocol was based on three sessions of squat-type exercise composed by three sets of 10 repetitions at 70% of maximal voluntary strength capacity.Results: the plantaris mass was significantly greater in both trained groups compared with the non-trained groups. Muscle cross-sectional area and fiber areas did not differ between groups. Both trained groups displayed significant increases in the number of intermediated fibers (IIa/IIx), a decreased number of fast-twitch fibers (IIb), an increased ratio of the proteins phospho(Ser2448)/ total mammalian target of rapamycin and phospho(Thr389)/total 70-kDa ribosomal protein S6 kinase. and a decreased ratio of phospho(Ser253)/total Forkhead box protein-3a. Plasma glucose was significantly increased in the DEX-LEU group compared with the DEX group and RE significantly decreased hyperglycemia. the DEX-LEU group displayed decreased glucose transporter-4 translocation compared with the DEX group and RE restored this response. LEU supplementation worsened insulin sensitivity and did not attenuate muscle wasting in rats treated with DEXA. Conversely, RE modulated glucose homeostasis and fiber type transition in the plantaris muscle.Conclusion: Resistance exercise but not LEU supplementation promoted fiber type transition and improved glucose homeostasis in DEXA-treated rats. (C) 2012 Elsevier Inc. All rights reserved.
Keywords Branched-chain amino acids
Glucose transporter-4
Muscle wasting
Mammalian target of rapamycin
Glucocorticoid
Language English
Sponsor Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Grant number FAPESP: 08/51090-1
FAPESP: 10/07062-3
FAPESP: 10/10852-6
FAPESP: 11/04690-6
Date 2012-04-01
Published in Nutrition. New York: Elsevier B.V., v. 28, n. 4, p. 465-471, 2012.
ISSN 0899-9007 (Sherpa/Romeo, impact factor)
Publisher Elsevier B.V.
Extent 465-471
Origin http://dx.doi.org/10.1016/j.nut.2011.08.008
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000302395800020
URI http://repositorio.unifesp.br/handle/11600/34723

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