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

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Date
2012-04-01Author
Nicastro, Humberto
Zanchi, Nelo Eidy
Luz, Claudia Ribeiro da
Moraes, Wilson Max Almeida Monteiro de
Ramona, Pamella
Siqueira Filho, Mario Alves de
Chaves, Daniela Fojo Seixas
Medeiros, Alessandra [UNIFESP]
Brum, Patricia Chakur
Dardevet, Dominique
Lancha Junior, Antonio Herbert
Type
ArtigoISSN
0899-9007Is part of
NutritionDOI
10.1016/j.nut.2011.08.008Metadata
Show full item recordAbstract
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.
Citation
Nutrition. New York: Elsevier B.V., v. 28, n. 4, p. 465-471, 2012.Keywords
Branched-chain amino acidsGlucose transporter-4
Muscle wasting
Mammalian target of rapamycin
Glucocorticoid
Sponsorship
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Collections
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