Initiating regular exercise protects against muscle atrophy from glucocorticoids.
This study was undertaken to examine whether exercise can prevent glucocorticoid-induced muscle atrophy in previously untrained individuals and to evaluate whether the time of hormone administration is a determinant in the muscle's response to glucocorticoids. Female rats were divided into five groups: 1) a sedentary group that received cortisol acetate (CA, 100 mg/kg body wt); 2) a sedentary group that received the dosing vehicle (1% aqueous carboxymethyl cellulose); 3) an exercise group that received CA immediately after each exercise session; 4) an exercise group that received CA 90 min after each exercise session; and 5) an exercise group that received the vehicle. Steroid treatment and exercise (28.7 m/min for 90 min/day) were performed for 11 consecutive days. Initiation of training prevented muscle mass loss by 60% in plantaris (P) muscles and by 25% in gastrocnemius (G) muscles. Time of steroid injection was not related to the muscle sparing response. In the glucocorticoid-treated exercised rats, the activities of citrate synthase, a training marker, increased 60% in P and 37% in G. Thus the exercise appeared to cause a greater recruitment of P muscles. These data support the hypothesis that entering into an exercise program can be effective in retarding glucocorticoid-induced muscle atrophy. The degree of atrophy prevention, however, may be related to the extent that specific muscles are recruited during exercise.
Department of Physical Education, University of Illinois, Chicago 60680.
S M
SM
Czerwinski
T G
TG
Kurowski
T M
TM
O'Neill
R C
RC
Hickson
D000818:Animals; D001835:Body Weight; D002950:Citrate (si)-Synthase / Q000378:metabolism; D005260:Female; D006854:Hydrocortisone / Q000633:toxicity*; D009133:Muscular Atrophy / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control*; D010806:Physical Education and Training; D051381:Rats; D011919:Rats, Inbred Strains; D014222:Triamcinolone Acetonide / Q000378:metabolism
D002950:Citrate (si)-Synthase; D014222:Triamcinolone Acetonide; D006854:Hydrocortisone