Progesterone downregulates oestrogen-induced expression of CFTR and SLC26A6 proteins and mRNA in rats' uteri.

UNLABELLED: Under progesterone (P) dominance, fluid loss assists uterine closure which is associated with pH reduction. We hypothesize that P inhibits uterine fluid secretion and HCO3⁻ transport.

AIM: To investigate the expression of Cystic Fibrosis Transmembrane Regulator (CFTR) and Cl⁻/HCO3⁻ exchanger (SLC26A6) under P effect.

METHOD: Uteri from ovariectomized steroid replaced and intact rats at different stages of oestrous cycle were analyzed for changes in protein and mRNA expressions.

RESULTS: P inhibits CFTR and SLC26A6 proteins and mRNA expression while oestrogen (E) causes vice versa. E treatment followed by P causes a reduction in these transporters' mRNA and protein. Similar changes occur throughout the oestrous cycle; that is, CFTR mRNA expression was high at proestrus while SLC26A6 mRNA and protein expressions were increased at proestrus and estrus. At diestrus, however, the expression of these transporters' protein and mRNA was reduced.

CONCLUSION: Inhibition of CFTR and SLC26A6 expressions may explain the reduced fluid volume and pH under P-mediated effect.