A QUANTITATIVE STUDY OF THE INHIBITION OF ESTRADIOL BENZOATE BY PROGESTERONE IN THE BABOON (PAPIO PORCARIUS)

Abstract

[longdash]The criteria used for the successful inhibition of estradiol benzoate by progesterone were the complete deturgescence of the turgescent perineum caused by estradiol and the production of progesterone withdrawal bleeding when both hormones were suspended. Two mg. of progesterone administered daily for 10 days with 1.0 to 10 mg. of estradiol benzoate to an immature baboon previously treated for 10 days with estradiol caused complete perineal deturgescence and progesterone withdrawal bleeding. In the castrated baboon the effective daily dose of progesterone necessary to antagonize 1 mg. of estradiol simultaneously administered varied from 2-4 mg. depending probably on the age of the animal. There was no proportional relationship between the antagonism of estradiol benzoate and progesterone in the immature and adult castrate baboon such as occurred in other animals. An adequate quantity of progesterone once available effectively antagonized 5-10 mg of estradiol benzoate daily. The successful antagonism of estradiol benzoate is dependent on the total quantity of progesterone used; in immature animals a minimum of 20 mg. is required as contrasted with 20-40 mg. for young and old adult castrate baboons respectively.