Clomiphene Citrate Causes Aberrant Tubal Apoptosis and Estrogen Receptor Activation in Rat Fallopian Tube: Implications for Tubal Ectopic Pregnancy1

Abstract

Clomiphene citrate (CC) therapy for disorders of anovulatory infertility has been linked to an increased frequency of tubal ectopic pregnancy. Although CC enhances apoptotic processes in the ovaries, villi, and decidual tissues, its effect on apoptosis in the fallopian tube is unknown. Here, we show that chronic treatment with CC induces tubal apoptosis, but not necrosis, through an intrinsic mitochondria-dependent signaling pathway in vivo. The apoptosis was specific to epithelial cells in the isthmus, and the damage was reversed with 17beta-estradiol (E2); however, pretreatment or concomitant treatment with E2 did not protect against tubal apoptosis induced by chronic treatment with CC. Chronic treatment activated estrogen receptors (ESRs), particularly cilia-localized ESR2A (formerly ERbeta2). In contrast to E2, acute treatment of superovulating rats with a high dose of CC or the ESR2-selective agonist 2,3-bis (4-hydroxyphenyl)-propionitrile (DPN) significantly delayed the transport of oocyte-cumulus complexes through the fallopian tube. Our findings suggest that in response to chronic CC therapy, isthmus-specific apoptosis of epithelial cells and activation of cilia-ESR2A act in parallel to block gamete and embryo passage through the fallopian tube, eventually resulting in tubal ectopic pregnancy.clomiphene citrate, ectopic pregnancy, estradiol receptor, estrogen receptor, fallopian tubes, intrinsic and extrinsic apoptotic pathways

Oviductal isthmus light microscopic changes induced by clomiphene citrate in albino rats

“…Presence of desquamated cells as well as bridging of the mucosal folds was noted. Consistently, these findings coincided with the results of some other authors [10,19] who reported the occurrence of hypertrophy and hyperplasia together with disorganization of the luminal epithelium of the rat isthmus after treatment with CC (10 mg/kg/day). Destruction of the tubal epithelial cell layers and impairment of epithelial cell function have been suggested as a cause of tubal ectopic pregnancy in humans [20].…”

“…Six animals were in the diestrus phase of their cycle and they were sacrificed under ether. (2) Group II (the CC group): animals of this group (n=7) received CC (1 mg/kg/day) for 4 days [10] orally through a gastric tube during the diestrus phase of their cycle [11]. Twenty-four hours after this chronic administration, they were sacrificed.…”

Coordinate regulation of heterogeneous nuclear ribonucleoprotein dynamics by steroid hormones in the human fallopian tube and endometrium in vivo and in vitro

“…Quantitative real-time RT-PCR (qRT-PCR) was performed with an ABI PRISM 7000 sequence detection system (Applied Biosystems, Foster City, CA). The PCR parameters were set according to the manufacturer's protocols, and the amplification protocol has been described (38,40). Tissues from the fallopian tubes of each patient were digested with RNase-free DNase I (Ambion) to remove genomic DNA.…”

“…Whole tissue extracts for protein preparations and Western blot analyses were carried out as described (39,40). Protein concentrations were determined with the Bradford assay.…”

Ectopic Pregnancy and Assisted Reproductive Technologies: A Systematic Review

“…Clomiphene citrate, which used for anovulatory infertility, may indirectly contribute to ectopic pregnancy creation. Chronic treatment with clomiphene activates estrogen receptors, particularly in cilia, and inducing tubal apoptosis of isthmus epithelial cells while slowing oocyte cumulus complex passage from the fallopian tube (Shao et al, 2009). This may contribute to ectopic pregnancy formation.…”