Amino acid neurotransmitters in postmortem human brain analyzed by high performance liquid chromatography with electrochemical detection.

In the present study we have developed a method of measuring putative neurotransmitter amino acids using high performance liquid chromatography (HPLC) with electrochemical detection. The assay had a sensitivity in the low pmol range and sample turnover time was 30 min. The postmortem stability of amino acids was examined in an animal model simulating human autopsy conditions. Aspartate concentrations increased 15% between 4 and 24 h postmortem while gamma-aminobutyric acid (GABA) concentrations rose 35% by 4 h but were stable thereafter. Glutamate and taurine were stable at all time points. The assay has been used to examine concentrations of neurotransmitter amino acids in 15 patients without neurological or psychiatric disease. Results agree well with previous work and knowledge of amino acid neurotransmitter pathways. The current technique provides a reliable method for the study of amino acid transmitter abnormalities in neurological illness.