Effects of various forms of progestin on the endometrium of the estrogen-primed, ovariectomized rat

Comparison of antiproliferative effects of metformine and progesterone on estrogen-induced endometrial hyperplasia in rats

Metformin has been shown to inhibit the growth of endometriotic implants, and reverse endometrial hyperplasia when combined with oral contraceptive in a case report. The aim of this study is to compare the antiproliferative effects of medroxyprogesterone acetate (MPA), and metformin in oopherectomized rat endometrium. Forty oopherectomized Wistar-Albino rats were used, and assigned to receive saline, 17 β Estradiol hemihydrate (4 mg/kg), 17 β Estradiol hemihydrate (4 mg/kg) and metformin (50 mg/kg), 17 β Estradiol hemihydrate (4 mg/kg) and MPA (1 mg/day) for 14 days. Histological markers of uterotrophy, including endometrial height, luminal ephitelial cell height and density of endometrial glands on hysterectomy speciments were quantified for each specimen. Rats treated with estradiol had significantly increased in endometrial height, endomerial luminal epithelial height and endometrial gland densitiy than the other groups. Metformin and MPA acetate significantly reduced all parameters indicating endometrial hyperplasia, and uterotrophy with respect to the control group. Antiproliferative effects of metformin, and MPA was found to be comparable for all three parameters. In conclusion, metformin attenuates estrogen-induced endometrial hyperplasia in ooferectomized rats to the same degree as progesterone.

Progestational effects of dydrogesterone in vitro, in vivo and on the human endometrium

Dydrogesterone has a molecular structure closely related to that of natural progesterone, but it has enhanced oral availability compared with progesterone. The hormonal profile and the progestational potency of dydrogesterone has been determined in vitro, in vivo and in humans, in combination with estrogens or without. It showed varying affinity for progesterone-binding proteins in uterine tissue in vitro, depending on the species. It exerted a clear progestational response in the rabbit in vivo, although the potency was influenced somewhat by the route of administration. When used in hormone replacement therapy, 10mg dydrogesterone given sequentially provides adequate protection against endometrial hyperplasia in postmenopausal women using 2mg estradiol. Similarly, a dydrogesterone dose of 5mg also protects the endometrium when continuously combined with 1mg estradiol. Dydrogesterone also has beneficial effects in women with amenorrhea/oligomenorrhea, dysfunctional uterine bleeding and irregular cycles. In conclusion, having a similar profile to progesterone but with better oral availability, dydrogesterone has been used successfully to treat disorders related to absolute or relative progesterone deficiency.