Expression of glucosamine trisaccharides on the rat uterine surface is altered by clomiphene citrate

Apoptosis is not altered by clomiphene citrate in pseudopregnant rat uteri

Clomiphene citrate (CC) remains one of the most often prescribed synthetic oestrogens used in the treatment of infertility even though the ensuing pregnancy rates are low. CC alters the uterine environment on most levels. Ovariectomised rats were treated with 5 mg progesterone (P) for 3 days and a 0.5 microg injection of oestrogen (E) on the third day (PP(PE)) thus inducing pseudopregnancy and rendering the uterus receptive to implantation 24 h later. Using this model, we investigated apoptosis in the rat uterus treated with 0.25 mg CC given prior to the PP(PE) treatment. Apoptotic cells in the uterus were localised using TUNEL and visualised with a FITC marker. There was a similar increase in apoptosis in the uterine luminal epithelium in the PP(PE) and CCPP(PE) treated animals; no changes were observed in apoptosis in the other uterine compartments when compared to the control. The CCPP(PE)-treated tissue showed tall epithelial cells with long microvilli while the PP(PE) tissue had short microvilli and low cuboidal epithelium. These results suggest that CC does not disrupt the normal apoptotic activity seen at implantation, but does change the morphology of the luminal epithelium, suggesting that these cellular changes could influence successful implantation.

Expression of glucosamine trisaccharides on the rat uterine surface is altered by clomiphene citrate. III. Relationship with implantation regimes and pregnancy

The present study further elucidates the complex effects of a commonly-prescribed fertility drug upon a target organ in an animal model. In the human condition, its effects are rarely observed without the influence of endogenous ovarian hormones. The aim of the study was to investigate how the administration of a single dose of clomiphene citrate (CC) given prior to an implantation-priming sequence of ovarian hormones would affect the expression of surface oligosaccharides and membrane architecture of uterine epithelium. Ovariectomized rats were given a single dose of either 0.25 mg or 1.25 mg of CC prior to a hormone-priming regime of progesterone (P4) for 3 days with a single additional administration of oestradiol 17beta (E2) on day 3. Animals were killed 24 h after final treatment. Uterine tissue was labelled with the lectin Phytolacca americana conjugated with avidin, subsequently labelled with biotinylated ferritin and prepared for transmission electron microscopy. Results indicate that CC, when administered prior to the implantation hormone-priming regime, is able to act as a super oestrogen and upregulates expression of oligosaccharides on the plasma membrane surface and increases the density and length of microvilli on the surface of the cells when compared with other treatment regimes. Understanding of the effects of CC at the uterine level at the time of implantation enables manipulation of uterine receptivity to control fertility and to improve the outcome of assisted reproductive procedures.

Expression of glucosamine trisaccharides on the rat uterine surface is altered by clomiphene citrate. II. Combination with ovarian hormones

We used a single administration of clomiphene citrate (CC), a synthetic oestrogen that is prescribed for infertility treatment, in combination with either a single administration of oestradiol 17beta (E2) or progesterone (P4) to assess the combined effects of these hormones on the uterine surface. The aim of these experiments was to investigate how CC in combination with these hormones affected both expression of oligosaccharides on the uterine surface and membrane architecture further elucidating CC's agonistic/antagonistic properties. Ovariectomized sexually mature rats were given combinations of E2 and CC (E2 + CC) or P4 and CC (P4 + CC) or P4 and E2 (P4 + E2) and were killed 24 h later. Uterine tissue was labelled with the lectin Phytolacca americana conjugated with avidin and subsequently labelled with biotinylated ferritin and prepared for transmission electron microscopy. Results of the administration of these hormone combinations indicate that CC, when administered in conjunction with E2, had the ability to downregulate expression of oligosaccharides on the membrane surface caused by E2. When administered with P4, CC had the ability to upregulate the effects of P4. Thus, when combined with E2, CC has an antagonistic effect but when combined with P4, CC has an agonistic effect.