Evidence for the occurrence of the opioid octapeptide dynorphin-(1–8) in the neurointermediate pituitary of rats

Abstract

Evidence is provided for the existence of the opioid peptide dynorphin-(1–8) in the neurointermediate pituitary of rats. The octapeptide was isolated by immunoadsorption to antibodies directed against porcine dynorphin-(1–13) followed by a variety of chromatographic separation procedures. The identity of the purified material with dynorphin-(1–8) was indicated by the following criteria: comigration with synthetic dynorphin-(1–8) on gelfiltration chromatography and high-performance liquid chromatography systems and liberation of a peptide with the same chromatographic behavior as leucine-enkephalin after sequential cleavage with trypsin and carboxypeptidase B. Radioimmunological estimations revealed that dynorphin-(1–8) is a major dynorphin-related opioid peptide in the pituitary of rats.