Genistein-induced fluid accumulation in ovariectomised rats' uteri is associated with increased cystic fibrosis transmembrane regulator expression

Abstract

OBJECTIVE:High genistein doses have been reported to induce fluid accumulation in the uteri of ovariectomised rats, although the mechanism underlying this effect remains unknown. Because genistein binds to the oestrogen receptor and the cystic fibrosis transmembrane regulator mediates uterine fluid secretion, we hypothesised that this genistein effect involves both the oestrogen receptor and cystic fibrosis transmembrane regulator.METHODS:Ovariectomised adult female Sprague-Dawley rats were treated with 25, 50, or 100 mg/kg/day genistein for three consecutive days with and without the ER antagonist ICI 182780. One day after the final drug injection, the animals were humanely sacrificed, and the uteri were removed for histology and cystic fibrosis transmembrane regulator mRNA and protein expression analysis using real-time polymerase chain reaction and Western blotting, respectively. The cystic fibrosis transmembrane regulator protein distribution was analysed visually by immunohistochemistry.RESULTS:The histological analysis revealed an increase in the circumference of the uterine lumen with increasing doses of genistein, which was suggestive of fluid accumulation. Moreover, genistein stimulated a dose-dependent increase in the expression of cystic fibrosis transmembrane regulator protein and mRNA, and high-intensity cystic fibrosis transmembrane regulator immunostaining was observed at the apical membrane of the luminal epithelium following 50 and 100 mg/kg/day genistein treatment. The genistein-induced increase in uterine luminal circumference and cystic fibrosis transmembrane regulator expression was antagonised by treatment with ICI 182780.CONCLUSION:Genistein-induced luminal fluid accumulation in ovariectomised rats' uteri involves the oestrogen receptor and up-regulation of cystic fibrosis transmembrane regulator expression, and these findings reveal the mechanism underlying the effect of this compound on changes in fluid volume in the uterus after menopause.

Estrogen, progesterone, and genistein differentially regulate levels of expression of α-, β-, and γ-epithelial sodium channel (ENaC) and α-sodium potassium pump (Na+/K+-ATPase) in the uteri of sex steroid–deficient rats

“…As plasma estrogen levels reached the levels observed at proestrus, i.e., after 0.2 mg/mL estrogen injection, relatively higher a-, b-, and g-ENaC expression could result in increased Na þ and fluid reabsorption from the uterine lumen. However, studies have shown that administration of 0.2 mg/mL estrogen to ovariectomized rats resulted in increased uterine fluid accumulation [2,20]. These findings indicated that despite of elevated expression of a-, b-, and g-ENaC by estrogen, an even higher upregulation of other transporters/channels that participate in uterine luminal fluid imbibitions such as AQP2 [41] and CFTR [2] could result in the net fluid secretion.…”

“…Genistein was given at doses of 25, 50, and 100 mg/kg/ day as these were the doses which have been previously shown to induce fluid, Na þ , and Cl À secretion in the uterus [19,20,23]. Meanwhile, concomitant administration of genistein with ICI 182780 was intended to confirm that genistein effect was mediated through ER binding.…”

“…Genistein effect has been shown to involve cystic fibrosis transmembrane regulator (CFTR), a channel that participates in fluid, Cl À , and HCO 3 À secretion [20]. Genistein is widely consumed in humans as a dietary health supplement after menopause and was found effective in alleviating postmenopausal complications such as female reproductive tract atrophy.…”

Enhanced expression of sodium hydrogen exchanger (NHE)-1, 2 and 4 in the uteri of rat model for post-menopause under phytoestrogen genistein influence

“…These findings have raised the possibility that genistein could be used as an agent to support implantation of the embryo transferred into the postmenopausal uterus for purposes such as surrogacy. In addition to stimulating H + secretion via NHEs, genistein has also been reported to stimulate secretion of fluid and other electrolytes such as Na + and HCO 3 − via Cystic Fibrosis Transmembrane Regulator (CFTR) (Chinigarzadeh et al, 2014b), Cl − /HCO 3 − exchanger (SLC26A6) and Na + /HCO 3 − cotransporters (NBCe1A and B) (Chinigarzadeh et al, 2014a). The effects of genistein could create a favorable uterine environment not only for the embryo to implant but also for pregnancy progression and thus could help to increase the success rate of surrogacy in women after menopause.…”

Effects of Endocrine-disrupting Chemicals on Female Reproductive Health

“…A recent paper showed that the oocytes are themselves competent for fertilization and early embryonic development, but the uteri are unable to support viable implantations: the sites were smaller and fewer in number [188]. Another study has shown that genistein induces fluid accumulation in the uterus in ovariectomized rats via ER signaling and the cystic fibrosis transmembrane regulator [189]. These results not only confirm the effect of genistein as an EDC but also shed light on the mechanism of fluid retention, in this case, as a therapy for menopausal conditions.…”