BRAIN CONTENT AND PLASMA-CONCENTRATIONS OF ARGININE VASOPRESSIN IN AN AUSTRALIAN MARSUPIAL, THE BRUSHTAIL POSSUM TRICHOSURUS-VULPECULA

Arginine vasopressin (AVP) has been identified and quantified in the brain and plasma of the possum using a highly specific radioimmunoassay and high-performance liquid chromatography. Large amounts of AVP were found in the pituitary (16.3 ± 0.56 Wg/pituitary, n = 5) and hypothalamus (398 ± 82.5 ng/hypothalamus), and significant amounts of AVP were also present in the cerebral cortex (26.8 ± 11.5 ng/cortex). Plasma AVP concentrations were significantly lower (2.2 ± 0.45 pg/ml, n = 10) during anesthesia compared to concentrations while conscious (4.5 ± 1.19 pg/ml). Severe hemorrhage markedly increased plasma concentrations to 1091 ± 225 pg/ml (n = 8). It was concluded that AVP is present in the possum brain, pituitary, and plasma, and that its secretion is stimulated by hypovolemia and inhibited by surgical stress. © 1992.