Uterine Prostaglandin F2α Content and 20α-Hydroxysteroid Dehydrogenase Activity of Individual Ovarian Compartments During Pseudopregnancy in the Rat

To investigate relationships between prostaglandin F 2α (PGF 2α ) and ovarian 20α-hydroxysteroid dehydrogenase (20α-OH SDH), uterine PGF 2α content and ovarian 20α-OH SDH activity were measured during pseudopregnancy in the rat. Quantitative cytochemical techniques were employed to assess 20α-OH SDH activity in individual compartments of the rat ovary. The data indicate appreciable 20α-OH SDH activity in corpora of pseudopregnancy, in involuting corpora formed in estrous cycles prior to pseudopregnancy, and in the interstitial tissue of the ovary of the pseudopregnant rat. Although enzymatic activity remained unchanged in the latter two compartments between Days 6 and 15 of pseudopregnancy, a twofold elevation in corpora of pseudopregnancy 20α-OH SDH activity was evidenced between Days 11 and 15. The close temporal relationship between increased uterine PGF 2α content (beginning on Days 9-10, peak on Days 11-12) and increased 20α-OH SDH activity in corpora of pseudopregnancy provides further evidence implicating PGF 2α as the putative factor responsible for inducing luteal 20α-OH SDH activity during luteal regression in the rat.