Estrogen-Progesterone Antagonism on Endometrial Carbonic Anhydrase Activity. ∗

Abstract

There is ample evidence concerning estrogen-progesterone antagonism in the uterine endometrium. Much has been demonstrated by the histological test based on the proliferative changes in the uterus, the response being rated on the semiquantitative scale. However, little has been done to utilize enzyme determinations in the endometrium as an indicator of hormonal antagonism.

Lutwak-Mann and Adams 1 have studied the effect of stilbestrol on development of progestational activity by the measurements of uterine carbonic anhydrase and progestational proliferation. They observed that in the enzymic test stilbestrol prevented progestational development, and noted that with few exceptions there was good agreement between the enzymic and histological test in evaluating the antagonism.

More recently a work of Miyake and Pincus 2 , concerning the antiprogestational activities of estrogens, namely estradiol, estrone, estriol and stilbestrol, in Clauberg rabbits provided quantitative evidence of the antagonism by estimating carbonic anhydrase activity in the uterine endometrium. This was also associated extremely well with proliferative changes (ratio of glandular to total mucosal area). They suggested thereby the superiority of estimation of uterine carbonic anhydrase as a quantitative test for antiprogestational activity.

The present investigation was made to as certair? whether the following estrogens are capable of affecting the enzymic response to progesterone in the uterine endometrium; estradiol? ethinyl es tradiol, hexes trol? es trone-3-methyl ether and estriol-3-methyl. ether.

Material and Methods. Immature albino rabbits, approximately 1.5 kg in weight, were used. All of the animals were primed with once daily subcutaneous injections of 5 pg estradiol each for 6 days, according to the Clauberg method 3 . The animals were then injected subcutaneously with progesterone and/or test compounds, once daily for 5 days. The test compounds dissolved in sesame oil to graded concentration were used and injection volume was 0.2 cc per animal daily.