Determination of neuropeptides in discrete regions of the rat brain by high-performance liquid chromatography with electrochemical detection.

High-performance liquid chromatography (HPLC) in combination with electrochemical detection (ED) is suitable for measuring accurately the levels of oxidizable neuropeptides in small samples of brain tissue. We have determined by HPLC-ED and a two-column-switching technique the levels of leucine- and methione-enkephalin in rat brain. By a sequential two-column HPLC-ED method we have also determined the levels of cholecystokinin tetrapeptide and octapeptide sulphate in various regions of the rat brain. The values found are in good agreement with those reported previously based on radioimmunoassay. We conclude that, due to its simplicity, HPLC-ED is an attractive alternative to existing methods for the determination of some neuropeptides in biological material.