Mesotocin receptors during pregnancy, parturition and lactation in the tammar wallaby

Abstract

Mestocin receptor concentrations in membrane preparations from reproductive tissues of the tammar Macropus eugenii throughout gestation and lactation were assessed using [3H]-oxytocin as the ligand. There was a single binding site which bound both mesotocin and oxytocin with high and similar affinities. Mesotocin receptor concentrations in the myometrium were low (708 ± 199 fmol mg-1 protein) in early and middle gestation but increased significantly on day 23 of pregnancy of the 26-day gestation period to 1921 ± 552 fmol mg-1 protein. Myometrial receptors reached a peak of 2483 ± 575 fmol mg-1 protein on days 25 and 26 of gestation, but returned to basal levels about an hour after birth. Rec..