THE EFFECTS OF SOME ANTIOESTROGENS ON THE UPTAKE OF [6,7-3H]17β-OESTRADIOL BY TISSUES OF THE DOMESTIC FOWL

Abstract

ABSTRACT Groups of laying domestic fowl were injected intramuscularly with doses of 1.2, 2.5 and 10.0 mg DMS (dimethylstilboestrol)/kg body weight for 7 days. No effect on the laying pattern was detected. The effect of intravenously administered DMS was examined at two dose levels on the distribution of radioactivity after the administration of tritiated oestradiol to the laying hen. At a level of 1 mg/kg body weight, DMS accelerated the rate of clearance of radioactivity from the plasma relative to that in control birds which received only injection vehicle in place of DMS. At the level 10 mg/kg body weight, DMS produced the reverse effect, i. e. a decrease in the rate of clearance of radioactivity from the plasma, with a corresponding, significant increase in the levels of radioactivity in all tissues examined (pituitary, median eminence, cerebral cortex and magnum). Doses of progesterone and testosterone propionate which would retard oviposition, when administered iv to hens 20 hours prior to the normal time of oviposition, were selected. The immediate effects (1.5 min later) of these compounds on the distribution of radioactivity after the administration of tritiated oestradiol were determined. Neither testosterone propionate (5 mg/kg body weight) nor progesterone (1 mg/kg body weight) affected the clearance of radioactivity from the plasma, and in the remaining tissues examined, only the uptake of radioactivity by the magnum was affected by either hormone: on a blood basis, the uptake of radioactivity in this tissue was depressed by the prior administration of testosterone propionate.