Assessment of Amino Acid Neurotransmitters in Rat Brain Microdialysis Samples by High-Performance Liquid Chromatography with Coulometric Detection

Abstract

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 (r²) > 0.999 over the concentration range from 0.1 to 15.00 µM (0.01–1.00 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 determining five major neurotransmitters because it shows quick separation and sensitive detection, and is easy to operate. This method can be a practical choice for continuous monitoring of the amino acid neurotransmittersin vivo.

Keywords:

• amino acid neurotransmitters
• awake animal
• coulometric detection
• high-performance liquid chromatography
• microdialysis
• olfactory bulb

Acknowledgments

The authors express their gratitude to Mrs. Erin Beatson for proofreading; with special thanks to the anonymous reviewers and the editor for their professional and intensive comments.

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