Evidence for a local fetal influence on myometrial oxytocin receptors during pregnancy in the tammar wallaby (Macropus eugenii)

Abstract

Mesotocin (MT), the oxytocin-like peptide of the tammar wallaby (Macropus eugenii) is important for delivery of live young. The tammar mesotocin receptor (MTR) was first characterized using the iodinated oxytocin receptor antagonist [125I]d(CH2)5 [Tyr(Me)2, Tyr4, Orn8, Tyr-NH29]-vasotocin. MTR concentrations were then measured in matched samples of gravid and nongravid myometrium and median vagina at different stages of the 26-day pregnancy. MTR concentrations in both the gravid and nongravid myometrium changed significantly (ANOVA, p < 0.01) during pregnancy. There was no difference in MTR concentrations between uteri on Days 8-22. From Day 23 of pregnancy, MTR concentrations in the gravid ..