EFFECT OF TESTOSTERONE ON SKELETAL-MUSCLE DEVELOPMENT AND PROTEIN-SYNTHESIS IN RABBITS

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  • 1 January 1976
    • journal article
    • research article
    • Vol. 40  (4) , 303-316
Abstract
The effect of testosterone administration on muscle development and protein synthesis was studied with intact male rabbits. Rabbits were randomized into 3 experimental groups; day 0 control (G-1), day 15 control (G-2) and day 15 testosterone (G-3). Testosterone (.DELTA.4-Androsten-17.beta.-ol-3-one in silastic tubing) was surgically implanted into the G-3 rabbits. On day 0 (G-1) and day 15 (G-2 and 3) of the experiment all rabbits were injected i.p. with 50 .mu.Ci-3H-leucine. Rabbits were sacrificed at intervals after the 3H-leucine injection. Right and left semitendinosus muscles, pituitary and adrenal glands, testicles and blood samples were obtained for analysis. Testosterone improved (P < .01) gain and feed efficiency, depressed testicle weight (P < .01), increased serum testosterone and insulin (P < 0.01) but did not affect adrenal and pituitary weights. Muscle moisture, fat and total protein, myofibrillar, sarcoplasmic and stromal protein fractions and RNA and DNA content were not significantly affected by testosterone although G-3 semitendinosus muscle had the highest total and myofibrillar protein, RNA and DNA content. The testosterone treated rabbits (G-3) had higher (P < 0.05) 3H-leucine incorporation into myofibrillar protein and lower 3H-leucine incorporation into sarcoplasmic protein than the day 0 and day 15 controls.