A simple method was developed for simultaneous determination of five amino acid neurotransmitters (taurine, glutamate, aspartate, glycine, and γ-aminobutyric acid) in brain microdialysates by high performance liquid chromatography with coulometric detection.The microdialysates were derivatized with o-phthalaldehyde in 5 mM sodium sulfite and separated within 17 min using isocratic elution. Detection parameters for these transmitters were linearity (r 2 ) > 0.999 over the concentration range from 0.1 to 15.00 μM (0.01 to 1.00 μM for GABA); reproducibility 2.88 -11.67% (relative standard deviation); the limits of detection 4.4 -17.2 fmol and recovery 86.66% -103.42%. This method was successfully applied to analyze these neurotransmitters in the brain. The changes of neurotransmitters were also investigated via local administration of potassium chloride and bicuculline, which was a γ-aminobutyric acid receptor antagonist. It was found that the developed method is more efficient as compared to previously reported methods in simultaneously Downloaded by [New York University] at 06:06 26 May 2015 2 determining five major neurotransmitters because it shows quick separation, sensitive detection, and is easy to operate. This method can be a practical choice for continuous monitoring of the amino acid neurotransmitters in vivo.

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