Intracellular regulation of endometrial PGF 2a and PGE 2 production in dairy cows during early pregnancy and following treatment with recombinant interferon-τ☆

Abstract

Objectives were to examine how the conceptus and recombinant bovine interferon-τ (rbIFN-τ) regulate intracellular components of the PGF 2a synthetic pathway and to determine if arachidonic acid (AA) is limiting in endometrial tissue of pregnant cows. In Experiment 1, uteri were collected from either cyclic or pregnant dairy cows on Day 17 post-estrus. Intercaruncular explants were dissected and incubated for 60 min to quantify PGF 2a production in response to oxytocin (10 −6 M), A23187 (10 −5 M), melittin (10 −5 M), and phorbol 12, 13 dibutyrate (PDBu, 10 −6 M). Additional explants from the same cows were incubated for 24 h with and without AA. Oxytocin and A23187 did not stimulate PGF 2a in explants from either cyclic or pregnant cows. Both PDBu, melittin, and A23187 + melittin stimulated PGF 2a production in explants of cyclic cows, but not in explants of pregnant cows. The addition of AA to explant cultures for 24 hr did not increase PGF 2a production during a subsequent 60-min incubation. In Experiment 2, explants were collected from cows that received intrauterine infusions of either BSA (1.9 mg/1.2 ml) or rbIFN-τ (0.2 mg rbIFN-τ + 1.7 mg BSA/1.2 ml) twice a day from Days 14 to 17 of the estrous cycle. Treatments of rbIFN-τ attenuated PGF 2a secretion induced by in vitro PDBu and A23187 treatments. However, rbIFN-τ treatment in vivo had no effect on the in vitro induction of PGF 2a secretion by melittin. IFN-τ may regulate the PGF 2a synthetic pathway by reducing activity of PKC or PKC mediated events.