Rapid method for micro-analysis of endogenous amino acid neurotransmitters in brain perfusates in the rat by isocratic HPLC-EC.

A simplified method is described for the isocratic analysis of endogenous amino acid neurotransmitters contained in brain perfusates by high performance liquid chromatography (HPLC) with electrochemical detection (EC). Pre-column o-phthalaldehyde (OPA) tert-butylthiol derivatives of the amino acids were injected into a C18 3 microns column. After linear concentration curves for standard solutions were obtained, the content of 6 amino acid neurotransmitters was analyzed in push-pull perfusates obtained from the hypothalamus and cerebral cortex of the unrestrained rat. Each analysis which included the simultaneous quantification of aspartic acid, glutamic acid, glutamine, glycine, taurine and gamma-aminobutyric acid (GABA), was completed in less than 15 min. The sensitivity of the assay ranged from 1.0 to 5.0 pmol of each amino acid contained within a 20 microliters aliquot of each perfusion sample.