Control of endometrial phosphoinositide hydrolysis and prostaglandin F2α a secretion in pigs

Abstract

This study examined the control of endometrial phosphoinositide (PI) hydrolysis and prostaglandin (PG) F_2α release by oxytocin (OT) and vasopressin in cyclic pigs on Day 15 post oestrus. In Expt 1, OT and arginine-vasopressin (AVP) increased endometrial PI hydrolysis (P<0.01), but only OT stimulated (P<0.01) PGF_2α secretion. In Expt 2, OT and lysine-vasopressin (LVP) increased PI hydrolysis (P<0.01). No difference was detected between the 100 n and 200 n concentrations of OT or between the 100 n and 200 n concentrations of LVP. The increase in PI hydrolysis was greater (P<0.05) for 100 n OT plus 100 n LVP than for the 100 or 200 n concentrations of OT or LVP alone. In Expt 3, OT (P<0.01) and LVP increased (P<0.01) PI hydrolysis. An OT antagonist abolished (P<0.01) the OT-induced increase in PI hydrolysis, but did not significantly alter the LVP-induced increase. A type 2 VP antagonist completely inhibited (P<0.01) the LVP-induced increase in PI hydrolysis, but only partially antagonized the stimulatory effect of OT (P<0.01). These results are consistent with the proposal that OT acts through specific receptors to promote endometrial PGF_2α secretion in pigs.