Release of an oxytocic peptide at parturition in the marsupial, Macropus eugenii

Abstract

The oxytocic peptide mesotocin was measured in plasma samples collected throughout pregnancy in the conscious tammar wallaby, Macropus eugenii. Plasma mesotocin and the prostaglandin metabolite 13,14-dihydro-15-oxo-prostaglandin F(2α) were also assessed immediately prepartum and during parturition. A radioimmunoassay for mesotocin was validated in the tammar and this assay allowed direct measurement in 50 μl unextracted plasma with a sensitivity of 12.5 pmol l-1. Plasma concentrations of mesotocin remained basal (approximately 15 pmol l-1) at all stages of pregnancy, including prepartum. A significant (P < 0.05) increase in plasma mesotocin was observed only immediately after delivery of the..