Biology of Reproduction, Vol 12, 305-314, Copyright © 1975 by Society for the Study of Reproduction

Induction of Uteroglobin in Rabbits by Progestogens, Estradiol-17 and ACTH

¹ The Department of Reproductive Biology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106

The appearance of uteroglobin in the uterine lumen of oöphorectomized does was induced by progesterone, 20-hydroxypregn-4-en-3-one (20-OHP), 5-pregnan-3,20-dione (5-DHP), estradiol-17 and adrenocorticotrophic hormone (ACTH). Progesterone (2.0 mg/kg body weight) stimulated a greater total amount of uteroglobin (P < 0.05) in mature animals than in immature animals although the endometrial progestational response in McPhail units was "4" in both types of animals. The induction of uteroglobin by 20-OHP. 5-DHP or estradiol was about 10-15% of the response to progesterone. The endometrial proliferative index in McPhail units was "0" following estradiol (2 µg/kg), 5-DHP (0.25-1.0 mg/kg), or 20-OHP (0.1-1.0 mg/kg). In mature rabbits the combined treatment of 2.0 µg/kg of estradiol and 0.01 mg/kg-0.075 mg/kg of progesterone gave a significantly higher (P < 0.05) uteroglobin induction as compared to progesterone treatment alone, but the progesterone and estradiol effects were additive. When the dose of progesterone was increased to 0.25 or 2.0 mg/kg, 2 µg/kg of estradiol did not significantly increase the uteroglobin (P < 0.05) in the uterine fluid of mature or immature animals. The plasma levels of progesterone determined on the 5th day of progesterone administration could not be correlated with the amount of uteroglobin present in the uterine fluid and preliminary evidence is presented which indicates that the rabbit adrenal might be a signficant source of progesterone. The administration of 40 I.U. of porcine ACTH for 5 days to oöphorectomized rabbits induced uteroglobin in the uterine fluid. In ACTH treated animals the uterus also responded with a typical progestational response. Three different combinations of pH and gel concentration were used to establish the identity of uteroglobin produced by the various treatments.