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.
Czerwinski
S M
SM
Department of Physical Education, University of Illinois, Chicago 60680.
Kurowski
T G
TG
O'Neill
T M
TM
Hickson
R C
RC
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