A quantitative evaluation of the effect of testosterone on RNA metabolism in the seminal vesicle of the rat.

Androgen dependent gross changes in RNA concentration of the androgen responsive cells of rat seminal vesicle were monitored by measuring RNA/DNA ratios. The time course of the changes in the RNA/DNA ratio following castration and after replacement of testosterone obeys the predictions of a kinetic model which permits determination of the rate constants for RNA degradation separately for the state of withdrawal and replacement of testosterone. For both states the apparent rate constant for RNA degradation was found to be 0.4 day-1/t1/2 approximately or equal to 1.8 days). The rate constant was shown to be independent of the testosterone dose applied. The testosterone-induced increase in the RNA/DNA ratio could be prevented by the administration of Actinomycin D. These findings are consistent with the view that testosterone controls the RNA level in vesicular target cells through the regulation of the rate of RNA synthesis. The results indicate that the rate of RNA synthesis in the vesicular cells of castrated rats is a regular hyperbolic function of the dose of testosterone propionate administered to these rats. On the basis of this finding a new approach to the accurate determination of the relative androgenicity of androgenic steroids is suggested.