Hirata J, Kikuchi Y, Imaizumi E, Furuya K, Nagata I
Department of Obstetrics and Gynecology, National Defense Medical College, Saitama, Japan.
J Obstet Gynaecol Res. 1996 Oct;22(5):497-506. doi: 10.1111/j.1447-0756.1996.tb01063.x.
In order to elucidate the roles of inositol trisphosphate (IP3) and oxytocin (OT) receptors in rabbit parturition, the concentration of IP3 induced by OT and the OT receptor levels were determined in rabbit myometria before and after parturition.
The effects of OT on IP3 formation and OT receptor levels were determined in the myometria of non-pregnant rabbits, Days 26, 28 and 30 of pregnancy rabbits, postpartum rabbits within 12 hours and steroid-treated ovariectomized rabbits. Prostaglandins (PGs) levels were also measured in the myometrial and decidual tissues.
OT receptors were not detectable in the myometria of non-pregnant rabbits, and OT had no effect on the formation of inositol phosphates (IPs). On Day 28 of pregnancy, OT receptors became detectable, and then OT could induce the formation of IPs. Thereafter, the stimulatory effects of OT on IPs formation and the OT receptor levels dramatically increased toward the end of pregnancy and reduced rapidly after parturition. When the ovariectomized pregnant rabbits were treated with estrogen, OT receptors in the myometrium were induced, and OT acquired the ability to stimulate IP3 formation. However, OT had no effect on the production of cAMP, cGMP, prostaglandin (PG) E2 and F2 alpha in the myometria, even if receptors existed, although PGE2 production in the decidual tissues was markedly stimulated. In addition, an OT receptor antagonist inhibited the stimulatory effects of OT on IP3 formation.
These results suggest that the formation of IPs by OT, the OT receptor levels in the myometrium, and the production of PGF2 in the decidua might play crucial roles in parturition.
为阐明肌醇三磷酸（IP3）和催产素（OT）受体在兔分娩中的作用，测定了分娩前后兔子宫肌层中OT诱导的IP3浓度及OT受体水平。
测定了非孕兔、妊娠第26、28和30天的兔、产后12小时内的兔以及用类固醇处理的去卵巢兔子宫肌层中OT对IP3形成和OT受体水平的影响。还测定了子宫肌层和蜕膜组织中的前列腺素（PGs）水平。
非孕兔子宫肌层中未检测到OT受体，OT对肌醇磷酸（IPs）的形成无影响。妊娠第28天，可检测到OT受体，随后OT可诱导IPs的形成。此后，OT对IPs形成和OT受体水平的刺激作用在妊娠末期显著增加，分娩后迅速降低。当用雌激素处理去卵巢的妊娠兔时，子宫肌层中的OT受体被诱导，OT获得了刺激IP3形成的能力。然而，即使存在受体，OT对子宫肌层中cAMP、cGMP、前列腺素（PG）E2和F2α的产生也无影响，尽管蜕膜组织中的PGE2产生受到明显刺激。此外，OT受体拮抗剂抑制了OT对IP3形成的刺激作用。
这些结果表明，OT诱导的IPs形成、子宫肌层中的OT受体水平以及蜕膜中PGF2的产生可能在分娩中起关键作用。
