A sensitive coupled HPLC/RIA technique for separation of endorphins: Multiple forms of B-endorphin in rat pituitary intermediate vs. anterior lobe

A technique is described which couples High Performance Liquid Chromatography (HPLC) to radioimmuno assays (RIA), thus achieving high sensitivity with good specificity. This method allows the separation and detection of multiple forms of immunoreactive peptides. Using this procedure, we have characterized the B-E-like immunoreactivity in rat pituitary. It had been previously reported that most of the B-E-sized material in both intermediate and anterior lobe of rat pituitary is not true B-E1-31. We now report that N-acetyl B-E1-27, which is inactive at the opiate receptor, is indeed the predominant peptide in rat intermediate lobe, with B-E1-31 representing a low proportion of the immunoreactivity. On the other hand, the opiate active B-END1-31 is the predominant peptide in the anterior lobe. These findings have important implications for the physiological and behavioral roles of the pituitary opioids.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24297/1/0000563.pd