Myotrophic effects of anabolic steroids.

Abstract

An anabolic steroid, nandrolone decanoate, was shown to produce increases in the weight, cross-sectional area, tension-generating capacity and mean fibre diameter of a limb muscle, tibialis anterior (TA), in female rabbits. Despite suggestions in the literature of an exerciserelated effect of such drugs, hypertrophy was not observed in TA muscles subjected to chronic electrical stimulation, but was seen in the contralateral control muscles and in the muscles of both hind limbs in unoperated sedentary animals. The effect was confirmed in the TA of female guinea pigs, rats and mice, and could not be explained in terms of an increase in body weight. Compared to TA some other muscles, like EDL, plantaris and soleus in the rabbit, were less sensitive to treatment; others, like pubocaudalis in the rat and mouse, and temporalis in the guinea pig, were more responsive. The myotrophic effects were undiminished in adrenalectomised female rats, and could not therefore have been mediated by interference with the catabolic actions of circulating glucocorticoids, as had been proposed in an earlier hypothesis.