Vasopressin secretion induced by hypoxia in sheep: Developmental changes and relationship to β-endorphin release

Abstract

To investigate the developmental changes in the secretion of vasopressin and the potential role of β-endorphin as a stimulus to the release of vasopressin, the concentrations of these peptides were measured in fetal, newborn, and adult sheep after episodes of induced hypoxia. The studies confirm that hypoxia is a potent stimulus to the release of both vasopressin and β-endorphin in the fetal animal. In both the newborn lamb and the ewe, more profound hypoxia is necessary for a similar release. In the fetus, the release of both vasopressin and β-endorphin after hypoxia increased with gestational maturation. A comparison of control concentrations of both peptides, the discordance of release in the newborn lamb, and the absence of a change in concentrations of vasopressin with infusion of β-endorphin implies that these hormones are released in parallel but independently during hypoxic stress.