Isolation, assay, and secretion of individual human neurophysins

Abstract

Human neurophysin was isolated from acetone dried human posterior pituitaries and separated into 2 major neurophysin peptides by ion exchange chromatography and into 4 major peptides by preparative disk gel electrophoresis. Antisera raised in rabbits distinguished only 2 specific antigenic sites on the isolated neurophysin peptides. Individual sensitive and specific radioimmunoassays for 2 human neurophysins were developed. These assays were used to measure each neurophysin in unextracted human plasma. The 2 neurophysins are secreted independently in man. One assay measures a neurophysin that is specifically secreted in response to estrogen administration, estrogen stimulated neurophysin (ESN). The other assay measures a neurophysin that is specifically secreted in response to cigarette smoking, nicotine stimulated neurophysin (NSN). The mean ESN is 1.1 ng/ml±0.7 SD in women and 1.0 ng/ml±0.7 SD in men. The mean NSN is 0.9 ng/ml±0.2 SD in women and 0.6 ng/ml±0.3 SD in men. It is proposed that these may prove to be a specific human 'oxytocin neurophysin', ESN, and a human 'vasopressin neurophysin', NSN.