title: Low-intensity resistance training attenuates dexamethasone-induced atrophy in the flexor hallucis longus muscle.
abstract: This study investigated the potential protective effect of low-intensity resistance training (RT) against dexamethasone (DEX) treatment induced muscle atrophy. Rats underwent either an 8 week period of ladder climbing RT or remained sedentary. During the last 10 days of the exercise protocol, animals were submitted to a DEX treatment or a control saline injection. Muscle weights were assessed and levels of AKT, mTOR, FOXO3a, Atrogin-1 and MuRF-1 proteins were analyzed in flexor hallucis longus (FHL), tibialis anterior (TA), and soleus muscles. DEX induced blood glucose increase (+46%), body weight reduction (-19%) and atrophy in FHL (-28%) and TA (-21%) muscles, which was associated with a decrease in AKT and an increase in MuRF-1 proteins levels. Low-intensity RT prevented the blood glucose increase, attenuated the FHL atrophy effects of DEX, and was associated with increased mTOR and reductions in Atrogin-1 and MuRF-1 in FHL. In contrast, TA muscle atrophy and signaling proteins were not affected by RT. These are the first data to demonstrate that low-intensity ladder-climbing RT specifically mitigates the FHL atrophy, which is the main muscle recruited during the training activity, while not preventing atrophy in other limb muscle not as heavily recruited. The recruitment-dependent prevention of atrophy by low intensity RT likely occurs by a combination of attenuated muscle protein degradation signals and enhanced muscle protein synthesis signals including mTOR, Atrogin-1 and MuRF-1.
authors.affiliation: Joint Graduate Program in Physiological Sciences, PIPGCF UFSCar/UNESP, Rodovia Washington Luiz, km 235 Monjolinho, 676, São Carlos, SP, Brazil. Electronic address: andersongmacedo@yahoo.com.br.
authors.forename: Anderson G
authors.initials: AG
authors.lastname: Macedo
authors.affiliation: Joint Graduate Program in Physiological Sciences, PIPGCF UFSCar/UNESP, Rodovia Washington Luiz, km 235 Monjolinho, 676, São Carlos, SP, Brazil. Electronic address: andre.krug@bol.com.br.
authors.forename: André L O
authors.initials: AL
authors.lastname: Krug
authors.affiliation: Department of Physical Education - UNESP, Science Faculty, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01 - Vargem Limpa, Bauru, SP, Brazil. Electronic address: nayara.herrera@yahoo.com.
authors.forename: Naiara A
authors.initials: NA
authors.lastname: Herrera
authors.affiliation: Department of Physical Education - UNESP, Science Faculty, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01 - Vargem Limpa, Bauru, SP, Brazil.
authors.forename: Anderson S
authors.initials: AS
authors.lastname: Zago
authors.affiliation: Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada. Electronic address: jwerush@uwaterloo.ca.
authors.forename: James W E
authors.initials: JW
authors.lastname: Rush
authors.affiliation: Department of Physical Education - UNESP, Science Faculty, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01 - Vargem Limpa, Bauru, SP, Brazil; Joint Graduate Program in Physiological Sciences, PIPGCF UFSCar/UNESP, Rodovia Washington Luiz, km 235 Monjolinho, 676, São Carlos, SP, Brazil. Electronic address: slamaral@fc.unesp.br.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Amaral
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000633:toxicity*; D015153:Blotting, Western; D003907:Dexamethasone / Q000633:toxicity*; D008297:Male; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009133:Muscular Atrophy / Q000139:chemically induced / Q000473:pathology / Q000517:prevention & control*; D010805:Physical Conditioning, Animal; D051381:Rats; D055070:Resistance Training
chemical_list: D000893:Anti-Inflammatory Agents; D009124:Muscle Proteins; D003907:Dexamethasone
keywords: Glucocorticoids; Ladder-resistance training; Skeletal muscle