Vij Urmila, Kumar Anand, Sharma Kanhaiya, Kaushal Mishi, Mehra Raj
All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India.
Natl Med J India. 2006 Mar-Apr;19(2):64-9.
[corrected] Mifepristone is a synthetic antiprogestin which terminates early pregnancy. Since it interferes with the progesterone maintained decidua, we compared the effect of mifepristone on oestrogen and progesterone receptors, and on the biotransformation of these hormones in normal and deciduous uterus.
Ovariectomized rats were treated with an oestrogen-progesterone hormone regimen and deciduoma was induced by trauma in one horn of the rat uterus while the other served as a control under an identical hormonal milieu. Hormone receptor and biotransformation studies were done using radiolabelled oestradiol and progesterone with high specific activity.
The artificially formed decidual tissue was comparable with that of early pregnancy. Mifepristone replenished oestrogen and progesterone receptors which were suppressed by progesterone in both the normal and decidualized uterine horns. Inhibition of oestrogen receptors by progesterone correlated with decreased oestradiol levels at the site of action. Metabolism of progesterone to less potent compounds was promoted by mifepristone. The enzymatic activities of 17beta-hydroxysteroid dehydrogenase (which metabolizes oestradiol), and 20alpha-hydroxysteroid dehydrogenase and 5alpha-reductase (which metabolize progesterone) were altered by mifepristone.
The effect of mifepristone in varying the hormone receptor population and the availability of different levels of active metabolites of ovarian hormones have an Important role in the antiprogestin action of mifepristone.
米非司酮是一种终止早期妊娠的合成抗孕激素。由于它干扰由孕酮维持的蜕膜，我们比较了米非司酮对正常子宫和蜕膜化子宫中雌激素和孕激素受体以及这些激素生物转化的影响。
对去卵巢大鼠采用雌激素 - 孕激素激素方案进行处理，通过创伤诱导大鼠子宫一侧角形成蜕膜瘤，另一侧作为在相同激素环境下的对照。使用高比活性的放射性标记雌二醇和孕酮进行激素受体及生物转化研究。
人工形成的蜕膜组织与早期妊娠的蜕膜组织相当。米非司酮补充了正常子宫角和蜕膜化子宫角中被孕酮抑制的雌激素和孕激素受体。孕酮对雌激素受体的抑制与作用部位雌二醇水平降低相关。米非司酮促进孕酮代谢为活性较低的化合物。米非司酮改变了17β - 羟类固醇脱氢酶（代谢雌二醇）、20α - 羟类固醇脱氢酶和5α - 还原酶（代谢孕酮）的酶活性。
米非司酮在改变激素受体数量以及卵巢激素不同水平活性代谢物的可利用性方面的作用，在其抗孕激素作用中具有重要意义。
