Uptake and distribution of 3H testosterone in tissues of male Praomys (Mastomys) Natalensis

Summary Following the administration of labelled testosterone into 4–6 month old intact, or 24 h orchiectomized Praomys (Mastomys) Natalensis, the uptake of radioactivity by the prostate and other tissues was measured at different intervals. Two hours after the injection of the hormone, the concentration of radioactivity in the prostate was significantly higher than in most of the other organs, but less than that of the liver and kidney. Most of the radioactivity taken up by the liver and kidney disappeared 8–16 h after the administration of the hormone. Orchiectomy enhanced the uptake of the radioactivity by the prostate. Administration of unlabelled testosterone prior to the injection of labelled hormone or the addition of unlabelled testosterone in the incubation media significantly reduced the uptake of radioactivity by the prostate. These changes did not occur in the non target tissues. In an in vitro system prostatic tissue took up significantly more radioactivity than the diaphragm. These findings have been compared with the results of the similar experiments reported on the prostate of the male rat and the female Mastomys.