Neurohypophyseal hormone-like peptides in the ovine pineal gland using reverse-phase liquid chromatography and radioimmunoassay

A method is described for the determination of the neurohormone contents of ovine pineal tissue by radioimmunoassay (RIA) after successive fractionation on gel filtration in formic acid and reverse-phase liquid chromatography (HPLC). This method gives a good resolution for the neurohormones vasopressin, vasotocin and oxytocin, without a significant interference of aspecific cross-reacting of peptides with the RIA. An acid extract from ovine pineal tissue was found to contain amounts of immunoreactive AVP- and OXT-like peptides, whereas an AVT-like peptide was not detectable over background levels after HPLC with post-column RIA. It is concluded from our results that an AVT-like peptide is not present in ovine pineal tissue, and the pineal AVP- and OXT-like peptides appeared to be associated to neurophysin molecules.