Metabolic profiling of radioreceptor-assayable opioid peptides in a human pituitary ACTH-secreting tumor.

The profile of endogenous opioid peptides in the peptide-rich fraction obtained from a homogenate of an ACTH-secreting human pituitary tumor is presented. Gradient RP-HPLC is used to separate the mixture into peptide constituents. A preparation of opioid receptors is used in a radioreceptor assay with ethorphine - a relatively non-specific ligand that is used as a screen because it interacts with mu, sigma, and delta receptors - as the HPLC detector to detect a range of peptides that derive from proenkephalin A and POMC.