Weight gain and [3H]thymidine incorporation in accessory sex glands of castrated male rats after physiological doses of testosterone

ABSTRACT One month after castration male rats were injected daily with a physiological dose (2 × 50 μg) of testosterone for 10 days. At certain time intervals a pair of rats were injected with [3H]thymidine and killed one hour later. The accessory sex organs were weighed and processed for radioautography. The ventral prostate, dorsal prostate, seminal vesicle and coagulating gland showed a 2.5–4 fold increase in weight during treatment for 10 days with testosterone, whereas the weight of the preputial gland remained unchanged. The daily physiological dose of testosterone clearly increased the [3H] thymidine incorporation in all the accessory sex glands except the preputial gland where only a slight initial peak was observed. The labelling index showed a peak value 42–90 hours after the start of the testosterone treatment. After the peak the labelling index showed some fluctuation and then decreased to a steady state level, which was of the same magnitude as the control level in uncastrated rats. This study shows that the 42–90 hour peak in the labelling index is dose-dependent whereas the steady state labelling index is independent of the testosterone dose. The refractory time to the initial peak of the labelling index is also independent of the testosterone dose.