Groups of starved female rats were treated with either testosterone propionate, 19-norandrostenolone phenylpropionate (Nandrolone, Durabolin) or bovine growth hormone (BGH). The effect of these hormones on the concentration of the plasma unesterified fatty acids (UFA) was then studied in blood withdrawn from the heart daily. As controls groups of rats were treated with either oil or saline, i. e. the vehicles for the above named hormones. It was found that both testosterone and Nandrolone caused a marked increase in plasma UFA concentrations, similar to the effects obtained by growth hormone.
Accepting UFA as an index of the metabolic activity of adipose tissue, it is concluded that testosterone and its less androgenic derivative Nandrolone possess fat mobilizing properties. In view of the fact that during puberty in boys the subcutaneous fat tissue decreases as compared with girls and that eunuchs have a tendency to obesity, it is suggested that androgens play an active physiological role in adipose tissue metabolism.