The aromatase inhibitor anastrozole is associated with favorable embryo development and implantation markers in mice ovarian stimulation cycles

Adverse effect of assisted reproductive technology-related hyperoestrogensim on the secretion and absorption of uterine fluid in superovulating mice during the peri-implantation period

OBJECTIVES

This study aimed to investigate the potential mechanism of hyperoestrogensim elicited by ovulation induction affects endometrial receptivity and leads to embryo implantation abnormality or failure.

STUDY DESIGN

Establishment of ovulation induction mouse model. Changes in mouse body weight, ovarian weight, serum E2 level and oestrous cycle were observed. During the peri-implantation period, morphological changes in the mouse uterus and implantation sites and the localization and protein levels of oestrogen receptors ERα and ERβ, the tight junction factors CLDN3 and OCLN, the aquaporins AQP3, AQP4 and AQP8, and the sodium channel proteins SCNN1α, SCNN1β and SCNN1γ were observed. The expression and cellular localization of ERα, CLDN3, AQP8 and SCNN1 β in RL95-2 cell line were also detected by western blotting and immunofluorescence.

RESULTS

Ovarian and body weights were significantly higher in the 5 IU and 10 IU groups than in the CON group. The E2 level was significantly higher in the 10 IU group than in the CON group. The mice in the 10 IU group had a disordered oestrous cycle and were in oestrus for a long time. At 5.5 dpc, significantly fewer implantation sites were observed in the 10 IU group than in the CON (p<0.001) and 5 IU (p<0.05) groups. The probability of abnormal implantation and abortion was higher in the 10 IU group than in the CON and 5 IU groups. CLDN3, OCLN, AQP8 and SCNN1β in the mouse endometrium were localized on the luminal epithelium and glandular epithelium and expression levels were lower in the 10 IU group than in the CON group. The protein expression level of ERα was increased by 50% in the 10 IU group compared to the CON group. The expressions of CLDN3, AQP8, SCNN1β in RL95-2 cell line were significantly depressed by the superphysiological E2, ERα agonist or ERβ agonist, which could be reversed by the oestrogen receptor antagonist.

CONCLUSION

ART-induced hyperoestrogenism reduces CLDN3, AQP8 and SCNN1β expression through ERα, thereby destroying tight junctions and water and sodium channels in the endometrial cavity epithelium, which may cause abnormal implantation due to abnormal uterine fluid secretion and absorption.

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.

A randomized comparison of ovulation induction and hormone profile between the aromatase inhibitor anastrozole and clomiphene citrate in women with infertility

BACKGROUND

IN the present study we evaluated and compared the effects of ovulation and hormonal dynamics induced by anastrozole and clomiphene citrate in women with infertility.

MATERIALS AND METHODS

Thirty-three infertile patients, aged 25-41 years, were enrolled. Patients received either anastrozole 1 mg daily (AI group) or clomiphene citrate 100 mg daily (CC group) from cycle day 3 to day 7. Number of mature follicles (> or =18 mm), endometrial thickness, pregnancy rate and serial hormone profiles (follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E(2)), testosterone and progesterone) were measured on cycle day 3, day 8, day 10, the day of intrauterine insemination (IUI), day 7 after IUI and day 14 after IUI.

RESULTS

Baseline parameters were similar in the two groups, including age, body mass index, infertility duration and day-3 serum hormones except FSH. The mean FSH value on day 3 was significantly different (4.3 mIU/ml in the AI group vs. 6.3 mIU/ml in the CC group; p < 0.05). The women receiving anastrozole had fewer ovulatory follicles (1.2 in the AI group vs. 1.8 in the CC group; p < 0.05) and a thicker endometrium (10.6 mm in the AI group vs. 7.8 mm in the CC group; p < 0.05). The levels of progesterone and testosterone were similar during ovulation stimulation cycles in both groups. On the other hand, the AI group had a significantly higher LH level but a significantly lower E(2) level in the stimulation cycle.

CONCLUSION

Anastrozole has a high pregnancy rate, although it induces fewer ovulatory follicles compared with clomiphene citrate. The two drugs gave different responses of FSH, LH and E2 during stimulation cycles.