Induction of Uteroglobin in Rabbits by Progestogens, Estradiol-17β and ACTH1

Abstract

The appearance of uteroglobin in the uterine lumen of oophorectomized does was induced by progesterone, 20a-hydroxypregn-4-en-3-one (20a-OHP), 5a-pregnan-3,20-dione (Sa-DHP), estradioll7� 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 20a-OHP. 5a-DHP or estradiol was about 10-15% of the response to progesterone. The endometrial proliferative index in McPhail units was “0” following estradiol (2 �zg/kg). Sa-DHP (0.25-1.0 mg/kg), or 20a-OHP (0.1-1.0 mg/kg). In mature rabbits the combined treatment of 2.0 gig/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 izg/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 lU. of porcine ACTH for 5 days to oophorectomized 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.