Steroidogenesis in the testes and the adrenals of adult male rats after gamma-irradiation in utero at late pregnancy.

Pregnant rats were irradiated with 2.1 Gy gamma-ray of 60Co at day 20 of gestation. Seventy days after birth, the body weight of the fetally irradiated male pups was significantly lower than the control. The testes, ventral prostates and seminal vesicles were atrophied by irradiation, whereas no decreased weight of the adrenals was observed. Histological examination of the testes of the irradiated rats revealed a complete disappearance of germinal cells. Sertoli cells and Leydig cells appeared normal, and no apparent histological difference was observed in the adrenals between the control and the irradiated rats. Activities of microsomal delta 5-3 beta-hydroxysteroid dehydrogenase (HSD) + isomerase, 17 alpha-hydroxylase/C17,20-lyase, 17 beta-HSD and 7 alpha-hydroxylase per pair of testes were decreased in the irradiated rats (36-86% of the control). In contrast, no decreased activity of 20 alpha-HSD in the cytosol fraction was observed by irradiation. No decreased activity of adrenocortical enzymes, such as delta 5-3 beta-HSD + isomerase, 21-hydroxylase, 11 beta-/18-hydroxylase and 5 alpha-reductase, was also observed in the irradiated group. Concentrations of LH, FSH, TSH, prolactin, testosterone, progesterone and aldosterone in serum were measured by radioimmunoassay. Only the FSH concentration was significantly increased by the irradiation, while no difference was found in the concentration of other hormones. It was concluded that irreversible damage was induced in spermatogenesis and androgen production by the fetal irradiation, whereas corticoidogenesis was not affected.