Human seminal alpha-inhibins: detection in human pituitary, hypothalamus, and serum by immunoreactivity

An antiserum generated in rabbits against human seminal alpha-inhibin-52 has been used to develop a sensitive radioimmunoassay for the detection of alpha-inhibins. The alpha-inhibin-52 antiserum reacts with alpha-inhibin-92 and alpha-inhibin-31 with equal avidity. These peptides were found to be present in human pituitary, hypothalamus, and serum. In exclusion chromatography on Sephadex G-100, the immunoreactive material eluted in a large molecular size region. Immunoblot analysis of column-derived fractions of these extracts revealed the presence of alpha-inhibin-92. The mean concentrations of immunoreactive alpha-inhibin were found to be 7.2 ng/ml in normal adult male serum, 70.3 ng/g (wet weight) of pituitary, and 12.9 ng/g (wet weight) of hypothalamus. This communication reports on the evidence for the existence of gonadal peptides in the brain.