In male rats, fed for 10 weeks on a Torula yeast-based, low selenium and low vitamin E diet, the selenium level and the glutathione peroxidase activity in the blood and in several tissues decreased by 50 to 98% compared with animals that received the same basal diet supplemented with 0.25 mg Se/kg sodium selenite. In the testes, however, the selenium content did not differ from that of the control animals. Despite the low selenium levels in the extragonadal tissues and their increased requirement of this element due to the low vitamin E status, the selenium from an intravenously injected dose of sodium selenite was retained above all in the testes. After the removal of the pituitary gland, because of the decrease in the testicular mass and in the selenium content in the remaining testicular tissue, the amount of selenium in the testes was greatly reduced. After administration of pregnant mare's serum gonadotropin (PMS), due to the regeneration of the tissue and the simultaneous restoration of the selenium content, a relatively large amount of this element was shifted to the testes even though the selenium status in the other tissues was low. The results of these studies show that the selenium level in the male gonads is maintained by regulation mechanisms and that the supply of sufficient amounts of selenium to the testes has priority over the supply to other tissues.

SUMMARY The antagonistic action of 1,2α-methylene-6-chloro-Δ4,6-pregnadiene-17α-ol-3,20-dione-17α-acetate (cyproterone acetate) to testosterone propionate (TP) on the testes and accessory glands was investigated in hypophysectomized adult male rats. Treatment of the animals began on the day of hypophysectomy and was continued for 21 days. Daily subcutaneous injections of 0·3 or 1·5 mg. TP/100 g. body weight almost completely inhibited testicular atrophy and involution of the germinal epithelium. Simultaneous administration of 0·3 mg. oestradiol/100 g. body weight did not influence the effect of testosterone propionate. Cyproterone acetate inhibited the effect of testosterone propionate. The extent of inhibition was dose dependent. The antagonism to testosterone was manifested by reduction of testicular weight and by the inhibition of spermiogenesis. The latest stages of spermiogenesis were primarily influenced. Intratesticular cyproterone acetate together with subcutaneous administration of TP caused similar effects in the testes to those of subcutaneous administration. However, regression of the germinal epithelium in the injected testis seemed to be more pronounced than in the contralateral testis. The effects of TP on the accessory sex glands (prostate, seminal vesicles) were inhibited by simultaneous administration of cyproterone acetate. It is concluded that cyproterone acetate competitively inhibits the action of testosterone propionate on the target organs.

The release of lactogenic hormone (LGH) was studied at the onset of pseudopregnancy in 90 rats. The LGH-content of the pituitary glands was determined by the pigeon crop sac assay. Glass rod stimulation of the cervix during vaginal oestrus was followed by a significant decrease in the LGH-content of the pituitary glands, thus demonstrating a correlation between LGH-release and beginning pseudopregnancy. Anaesthesia by Nembutal almost prevented this effect of cervical stimulation.

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