Exercise training fails to prevent glucocorticoid-induced muscle alterations in young growing rats

Abstract

The aim of this study was to determine the impact of chronic treatment for 8 weeks with hydrocortisone acetate (5 mg kg-1 day-1) on skeletal muscles, and to evaluate whether sprint training can prevent glucocorticoid-induced muscle atrophy better than endurance training. Biochemical, histological and contractile properties were employed to determine the influence of this steroid on skeletal musculature, and the results were compared to pair-weight animals to take into account the influence of corticoids on growth rate. It was found that hydrocortisone acetate treatment results in a stunted growth, adrenal atrophy and depressed plasma corticosterone levels. Mild corticoid-induced losses of muscle mass and protein content (9%-13%) were observed in fast-twitch skeletal muscles. It appeared that the impact of corticoids is strictly directed toward type IIb fibres, which displayed a 12%-18% reduction in cross-sectional areas. No alterations occurred in plantaris contractile speed or tensions properties. Neither endurance training (30 m/min; 90 min/day; 5 days/week) nor sprint training (60 m/min; 15 min/day; 5 days/week) for 8 weeks was able to counteract the effects of corticoids. These data suggest that increased contractile activity, as induced by treadmill running, is not sufficient to counteract the muscular effects of glucocorticoids when administered at a dose of 5 mg kg-1 day-1.

Regulation of type IV collagen gene expression and degradation in fast and slow muscles during dexamethasone treatment and exercise

“…A preventive effect of endurance running against the catabolic effects of dexamethasone was observed in EDL and SOL, and is in good agreement with most of the earlier studies (e.g. [4,25]), although different findings have been published [8,15]. Although the decrease in TIMP-2 activity in TA was almost totally compensated by uphill running, no clear evidence of preventive effects of exercise against the changes in type IV collagen synthesis and degradation caused by dexamethasone treatment was obtained.…”

“…Data relating to the effect of physical activity on glucocorticoid-induced myopathy is contradictory: physical activity has been shown either to prevent [4,25], fail to prevent [8] or even enhance [15] the effects of glucocorticoids on muscle contractile component. The effects seem to be related to the type of exercise.…”

Physical Exercise, Aortic Blood Pressure, and Aortic Wall Elasticity and Composition in Rats

“…2,16 Furthermore, our training program produced marked increases in V O 2 max (ϩ34%) and skeletal muscle citrate synthase activity. These increases are similar to those obtained in previous studies, showing that aerobic capacity of the skeletal muscle is increased after the same training program 14 and that such a program is able to modify the mRNA expression of uncoupled proteins related to energy dissipation in skeletal and heart muscles. 15 A more plausible explanation for the difference between our results and those of Matsuda et al 3 resides in their use of forced swimming as exercise training.…”

“…In the present study, an 8-week period of treadmill running was used because such a forced running program is used to induce modifications of the skeletal muscle function and aerobic capacity in our laboratory. 14,15 Albeit, changes in the structure and mechanical properties of central arteries can occur relatively rapidly and over a time span similar to that of the present study. Structural and functional arterial alterations can develop in Յ2 months after the induction of hypertension 16 or elastocalcinosis, 1,2 and these alterations can be reversed equally rapidly.…”

Hormone-related, muscle-specific changes in protein metabolism and fiber type profile after faba bean intake

“…It has been well documented that fast-twitch fibers are more affected than slow-twitch fibers in response to glucocorticoids (e.g., Refs. 3,13). Selective atrophy of type IIb fibers has been reported to be associated with increased sensitivity to circulating glucocorticoids (10) because of an upregulation of cytosolic glucocorticoid receptors (31).…”