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

Histochemical Study of the Rat Uterine Glycoconjugate Alteration following Treatment with Exogenous Gonadotropic Hormones during the Implantation Period

One of the female causes of infertility is anovulation which is treatable with gonadotropin hormones. These hormones affect the molecular organization of the uterus such as glycoconjugates that are the first site of contact between the blastocyst and the uterus. The objective of this project was to study the alteration of glycoconjugates on the uterine apical, Golgi zone, and basement membrane of epithelial cells and the uterine gland after hyperstimulation with pregnant mare serum gonadotropin (PMSG) (4, 8, 16, 24, and 40 IU), during the implantation period. Injection of PMSG (in experimental groups) and injection of distilled water (in the control group) were followed by HCG administration (10 IU), mating, isolation of positive vaginal plug rats, and killing at 5.5 days of pregnancy. Histochemistry was done on the pregnant uterine horns with the use of WGA, DBA, PNA, ConA, SBA, and UEA lectins. The intensity of the immunohistochemical staining was scored, and quantitative data were generated. 4 IU did not show any significant differences with the control, 8 IU had less effect on the alteration of the Golgi zone, and apical and basement membrane glycoconjugates and 40 IU had the least effects on the alteration of uterine gland glycoconjugates. Also, 24 IU had the most effect on the alteration of uterine glycoconjugates. Understanding of the effects of gonadotropin hormones at the uterine level in implantation time helps to optimize hormonal manipulation for improving the outcome of assisted reproductive procedures. It seems that the optimal dose for superovulation and less alteration in uterine glycoconjugates of rats at implantation time were induced by the administration of 8 IU PMSG.

Anastrozole is a dose-specific superovulator and favors implantation in rats: a prospective study

An alternative superovulator to replace clomiphene citrate (CC) is needed as it is unsuitable for women with polycystic ovarian syndrome and is associated with low pregnancy rates. Anastrozole is an effective superovulator, but has not been well researched. The aim of this study was to determine the optimal dose of anastrozole as a superovulator and ascertain its effects on implantation and uterine ultrastructure during early pregnancy in Wistar rats using scanning electron microscopy. The uterine morphological characteristics which were studied in day 1 and 6 pregnant rats include microvilli density, length, surface "beads", surface glycocalyx, cell borders and apices, uterine surface fording and large surface protrusions. A significant increase in implantation sites is seen in the 15 mg/kg anastrozole group, compared to control. Day 1 and 6 anastrozole groups have similar morphology to the control and different to the CC group. At day 6, large surface protrusions are mostly noted but not limited to anastrozole-treated rats; anastrozole also appears to retain glycocalyx to some extent. The increased number of implantation sites in the 15 mg/kg anastrozole group suggests that this dose superovulates and favors implantation. Anastrozole is probably dose-/species-specific and additionally the surface uterine morphology suggests that anastrozole is implantation friendly.

Actin binding protein expression is altered in uterine luminal epithelium by clomiphene citrate, a synthetic estrogen receptor modulator

Clomiphene citrate (CC), a synthetic oestrogen, is often prescribed as a superovulator in treating infertility. Although CC works efficiently, pregnancy rates following CC treatment are approximately 10 times lower than "natural" rates. This study investigates how a dose of 1.25 mg CC given to ovariectomized rats before the implantation priming hormones (a single dose of progesterone for 3 days and a dose of estradiol-17beta on d3, P-P-PE), alters the expression and distribution of alpha-actinin, gelsolin and vinculin. Actin binding proteins show a specific distribution within the uterine epithelium during implantation, linking the actin cytoskeleton to integrin expression on the uterine surface and in this way aiding "adhesiveness" for blastocyst apposition to the uterine epithelium. In this study, immunocytochemistry on frozen uterine sections using mouse monoclonal antibodies against alpha-actinin, gelsolin and vinculin and peroxidase-conjugated secondary antibodies, show that CC, administered before the P-P-PE regimen, down-regulates the expression of vinculin, does not alter the expression of gelsolin and up-regulates alpha-actinin on the uterine apical surface, when compared to P-P-PE treated animals. All three proteins are down-regulated on the apical surface of the luminal epithelium and glands in all groups when compared to pregnant controls. Vinculin was only localized in the basolateral compartment of the uterine epithelial cells in the CC treated groups. By down-regulating these proteins on the uterine surface and up-regulating vinculin on the basolateral membrane of the epithelium, CC may impede adhesion and invasion of blastocysts at implantation. These results may aid the exogenous manipulation of uterine tissue to control fertility and improve assisted reproductive out-comes.

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.