CARBONIC ANHYDRASE IN THE FEMALE REPRODUCTIVE TRACT. II. ENDOMETRIAL CARBONIC ANHYDRASE AS INDICATOR OF LUTEOID POTENCY: CORRELATION WITH PROGESTATIONAL PROLIFERATION

Abstract

SUMMARY: In an attempt to establish the measurement of uterine carbonic anhydrase activity as a quantitative test for progestationally active substances, the activity of carbonic anhydrase in the rabbit endometrium has been correlated with the conventional histological method of assaying progestational activity. The following steroids have been tested in this manner with special regard to the duration of their effect: (a) progesterone, deoxycorticosterone (DC), deoxycorticosterone acetate (DCA), 3-acetoxy-pregna-3,5-diene-20-one, 17α-hydroxy-progesterone, 17α-hydroxyprogesterone caproate (Delalutin); (b) 17α-ethinyl-19-nortestosterone, 17β-acetoxy-isoprogesterone, 3α-hydroxy-pregnane-12:20-dione, 12α-hydroxy-pregnane-3:20-dione, pregnane-3:12:20-trione, 2β-acetoxy-progesterone, 2 α-acetoxyprogesterone, pregna-5-ene-20-one. The action of DCA was weak and transient; that of progesterone and 3-acetoxy-pregna-3,5-diene-20-one was marked but of limited duration; Delalutin was powerful as well as sustained; DC and 17α-hydroxyprogesterone failed to produce true progestational changes. Ethinyl-19-nor-testosterone was the only steroid in group (b) endowed with progestational potency. Stilboestrol (2 mg) administered a day before or simultaneously with DCA (16 mg), progesterone (4 mg) or Delalutin (2 mg), suppressed the endometrial response for 5 days but did not interfere with the late (8-day) progestational effect of the long-acting progestogen Delalutin. Small doses of purified FSH induced a few ovulations in the rabbit when injected intravenously, the endometrium showed some proliferative changes by bioassay but the activity of carbonic anhydrase was not appreciably increased. Subcutaneous injections had no effect. When progesterone was administered subcutaneously with FSH its effect was curtailed. With few exceptions, there was satisfactory agreement between the enzymic and histological method of determining progestational activity.