The Effect of Mifepristone Antiprogestrogen on the Number of Progesterone Receptors in the rat Uterus

Abstract

Objective: To investigates the effect of mifepristone on the number of progesterone receptors in the rat uterus. Study Design: Laboratory based randomized controlled trials. Place & Duration of the study: Department of Anatomy, Army Medical College Rawalpindi from Jan 2007-March 2007. Method: Sixty adult female rats were divided randomly into two groups, comprising of 30 animals in each group. In control group A one ml of normal saline was given orally daily for three months while in group B mifepristone was given orally in a dose of 1 mg/kg body weight daily for three months. All the animals were sacrificed next day after the last oral dose. Two ml blood was taken directly from the heart for measurement of estrogen and progesterone levels. About ½ cm piece of tissue was taken from the middle of the right uterine horn. Immunohistochemical staining procedure was done for demonstration of progesterone receptors Results: In the control group Total number of PR stained receptors in all the compartments of the uterus were 40400.  In the experimental group the number of progesterone receptors in all uterine compartments of the experimental group was 986 Significantly lower level of progesterone while higher levels of estrogen level were noted in the experimental group as compared to control group. Conclusion: Long term mifepristone administration suppresses the endometrial proliferation The number of progesterone receptors in all uterine compartments of the experimental group were decreased and found statistically significant It also lowered the plasma concentration of progesterone. While the plasma concentration of the estrogen was raised.