Abstract
After X-irradiation, the testicular weight of mice (6 weeks in age) decreased gradually, being significantly reduced on the 14th day post-irradiation and thereafter, in comparison to the control group.The specific activity of the 17α-hydroxylase in the testicular homogenate of the X-irradiated mice became higher than in the non-irradiated animals.When testes of the rats were locally X-irradiated, the weight of testes decreased almost half, but the weight of accessory organs remained almost unchanged.However, further detailed analysis of the individual enzymes of rat related to biosynthesis of androgens revealed that the 17α-hydroxylase and the 17α-hydroxypregnene C17-C20 lyase activities per testis were significantly reduced by local X-irradiation, while the Δ5-3β-hydroxysteroid dehydrogenase activity coupled with the isomerase was somewhat enhanced by this treatment. By administration of human chorionic gonadotrophin to the locally X-irradiated rats, the enzyme activities related to testosterone formation except 17β-hydroxysteroid dehydrogenase were stimulated, in accordance with the increased weight of accessory organs by the gonadotrophin. From the results that the specific activities of the enzymes related to androgen production were higher in X-irradiated than in the control, and that those activities were stimulated by the gonadotrophin in parallel with histological observation on proliferation of interstitial cells, the enzymes related to testosterone production from pregnenolone were intercellularly located to the interstitial cells and intracellularly to their microsomes.
