[Effect of testosterone and its 5-alpha-reduced metabolites on thyroid function and protein synthesis].

Experiments on male rats were made to study and compare the effect of testosterone, 5 alpha-dihydrotestosterone and 5 alpha-androstane-3 beta, 17 beta-diol on thyroid function and proliferation of thyroid parenchyma, as well as on protein synthesis by it. Administration of testosterone and androstanediol slightly increased intrathyroid hormonogenesis, while dihydrotestosterone reduced it. At the same time testosterone and, to a greater extent, its 5 alpha-reduced metabolites decreased the weight of the thyroid gland. This decrease and suppression of thyroid parenchyma proliferation under the effect of the compounds in question is accounted for by the inhibitory effect produced by all the test androgens on protein synthesis by thyrocytes.