Abstract

Forty years ago, testosterone was shown to have anabolic effects in animals¹ and certain synthetic derivatives (anabolic steroids) were claimed to have this anabolic action without the virilizing effects of testosterone.² These ‘anabolic steroids’ have found limited use in medicine; their ability to increase tissue mass in clinical conditions has never been adequately studied. Recent re-investigation of the effects of testosterone and its derivatives in rats³ failed to confirm the anabolic effect. The ‘rat levator ani’ assay, on which earlier conclusions largely depended, responds specifically to androgens and does not necessarily indicate a general somatic effect; and the enhanced growth of male animals is probably due to brief early exposure to testosterone which programs future development.^{4 5}