Lysophosphatidic acid stimulates rat uterine contraction in vitro

Lysophosphatidic acid (LPA) has been implicated in the uterine endometrial functions of implantation and decidualization; however, not much is known about its myometrial contractile function. Herein we characterized the uterotonic effects of LPA in non-pregnant (estrus) and peri-parturient rats in vitro. LPA dose-dependently (0.01–10 μM) stimulated the amplitude and integral, but not the frequency, of the uterine strip contraction of estrous rats. The stimulatory effect of LPA was enhanced 1 day before parturition but was lost 1 day postpartum. LPA did not cause the de novo synthesis of prostaglandin (PG) F(2)α but stimulated contractions cooperatively with the PG. LPA-induced contractions were significantly inhibited by an LPA1/2/3 antagonist in the uteri of estrous rats but not in term rats. This study characterized the uterotonic effect of a natural LPA that occurs at physiological concentrations, changes with reproductive states, and is independent of mediation by the newly synthesized PG.