Renfree M B, Parry L J, Shaw G
Department of Zoology, University of Melbourne, Parkville, Victoria, Australia.
J Reprod Fertil. 1996 Sep;108(1):131-7. doi: 10.1530/jrf.0.1080131.
The oxytocin receptor antagonist [1-deamino-2-D-Tyr-(OEt)-4-Thr-8-Om]-oxytocin (Atosiban) is a specific antagonist of both mesotocin- and oxytocin-induced myometrial contractions in late pregnant tammars in vitro. Continuous intravenous infusion of Atosiban (1 mg kg-1 day-1) for 3 or 7 days from day 24 of the 26.5 day gestation significantly delayed births. In both the 3 day and 7 day infusion groups, all 15 control animals were pregnant and gave birth within the normal time (day 26.75 +/- 0.20, mean +/- SEM), during the infusion of saline. The neonates weighed 387 +/- 8 mg. Deliveries were observed in 15 Atosiban-treated animals significantly (P < 0.05) later than in the controls (day 27.85 +/- 0.19; neonate weight 413 +/- 9 mg). All pouch young were successfully suckled, even in the continued presence of Atosiban. Baseline plasma concentrations of the prostaglandin F metabolite (PGFM) in pregnant tammars were < 200 pg ml-1. A surge in plasma PGFM occurred at birth (811 +/- 116 pg ml-1), followed by a rapid fall to baseline concentrations within 1 h after birth. This was observed both in saline- and in Atosiban-treated animals that gave birth during the observation period, and did not differ significantly between the treatment groups. Plasma progesterone concentrations in the control and the Atosiban-treated animals showed the normal pattern of luteolysis immediately after birth. Thus, infusion of an oxytocin receptor antagonist at the end of gestation delays birth, the peripartum surge in prostaglandin release, and the fall in progesterone, suggesting that mesotocin is an important part of the hormonal cascade associated with delivery in this marsupial.
催产素受体拮抗剂[1-脱氨基-2-D-酪氨酸-（OEt）-4-苏氨酸-8-鸟氨酸]-催产素（阿托西班）是体外妊娠晚期袋鼬中中催产素和催产素诱导的子宫肌层收缩的特异性拮抗剂。从26.5天妊娠期的第24天开始连续静脉输注阿托西班（1毫克/千克/天）3天或7天，可显著延迟分娩。在3天和7天输注组中，所有15只对照动物均怀孕并在正常时间（第26.75±0.20天，平均值±标准误）分娩，即在输注生理盐水期间分娩。新生幼崽体重为387±8毫克。15只接受阿托西班治疗的动物的分娩时间明显（P<0.05）晚于对照组（第27.85±0.19天；新生幼崽体重413±9毫克）。即使在持续存在阿托西班的情况下，所有育儿袋幼崽均成功哺乳。妊娠袋鼬中前列腺素F代谢物（PGFM）的基线血浆浓度<200皮克/毫升。出生时血浆PGFM出现激增（811±116皮克/毫升），随后在出生后1小时内迅速降至基线浓度。在观察期内分娩的生理盐水处理组和阿托西班处理组动物中均观察到这种情况，且治疗组之间无显著差异。对照组和阿托西班处理组动物出生后血浆孕酮浓度立即呈现正常的黄体溶解模式。因此，在妊娠末期输注催产素受体拮抗剂可延迟分娩、围产期前列腺素释放激增以及孕酮下降，这表明中催产素是这种有袋动物与分娩相关的激素级联反应的重要组成部分。
