Effect of Dosage on the Morphogenetic Actions of Testosterone

Abstract

Summary

Young male albino rats were divided into groups treated with daily doses of testosterone ranging from 0.1 to 25 mg per day. These experiments showed that the body weight as well as the weight of the pituitary, thyroid and thymus undergo a gradual decrease as the hormone dosage is increased. The seminal vesicle, prostate and epididymis increase in size with increasing dosage. On the other hand, the inhibitory action of testosterone on the adrenal and testis has a definite optimum at the 0.5 to 1.0 mg daily dose level, inasmuch as smaller doses cause less pronounced atrophy and larger amounts may actually stimulate the growth of these glands. The histological changes which accompany these variations in gross weight have been described. We conclude that many of the apparent contradictions concerning the morphogenetic actions of androgens—and perhaps also of other steroid hormones—are due to the fact that depending on the dose given, these compounds may exert diametrically opposite actions on certain organs.

The expenses of this investigation were defrayed through a grant in aid received from the Cooper Fund of McGill University. The author is especially indebted to Drs. G. Stragnell and E. Schwenk of the Schering Corporation of Bloomfleld, New Jersey, for supplying the large quantities of testosterone required for this work.