Bovine endometrial epithelial cells as a model system to study oxytocin receptor regulation

Endometrial epithelial cell cultures were established from bovine uterine t issue collected during the oestrous cycle from commercially slaughtered ani mals. These cells were shown to express moderately high levels of oxytocin receptors (OTR) (up to 30 000 per cell) after about one week in culture. Th ese receptors have been characterized at the molecular, pharmacological and functional level and shown to be identical to those expressed in the bovin e endometrium in vivo. Preliminary experiments to investigate the regulatio n of the OTR and its gene using this system, have shown that expression is to a large degree constitutive, the receptors being spontaneously upregulat ed during culture. Sex steroids at concentrations close to or above the ser um Limits observed in vivo appeared to have no effect, although the cells w ere shown to express mRNA for the specific steroid receptors throughout cul ture, Only the blastocyst product, interferon-tau, showed a significant eff ect, downregulating both OTR and their gene transcripts in the cultured end ometrial epithelial cells. Although more extensive studies are necessary, t hese results support the view that the OTR gene is controlled in part at le ast by a combination of constitutive and inhibitory elements.