Local biotransformation of des-Tyr1-gamma-endorphin in brain studied by a push-pull technique and HPLC analysis

The biotransformation of [3H]des-Tyr1-gamma-endorphin locally in rat brain was studied by perfusion of the peptide via a push-pull cannula implanted in the nucleus caudatus. Metabolites were analyzed by high-pressure liquid chromatography. Free [3H]phenylalanine and a [3H]peptide with chromatographic properties of beta-endorphin2-13 were formed during push-pull perfusion. The method presented enables the detection of local proteolytic events in the brain and provides a novel tool for studies on neuropeptide biotransformation.