gamma-aminobutyric acid in the murine brain: mass fragmentographic assay method and post-mortem changes.
An improved mass fragmentographic assay method for the determination of gamma-aminobutyric acid (GABA) in the brain is described. Applicability of the method was examined in a study of the effect of semicarbazide on GABA levels and in a separate study to confirm post-mortem increase in GABA. The method itself is based on Cattabeni's procedure in which GABA is assayed as trimethylsilyl derivative. Three improvements were made: a) application of a more suitable mass spectrometry system for GABA determination; b) use of 6-aminocaproic acid as the internal standard; c) selection f a high intensive ion (m/z 174) for mass fragmentographic analysis. The mass spectrometer used is accurate to as little as 25 pg. GABA levels after semicarbazide treatment decreased 54.4% in rat whole brain and 44.2% in the dorsal hippocampus. Rapid post-mortem increases in GABA levels were confirmed by application of the improved assay method; decreases were most clearly observable following microwave irradiation. Post-mortem changes in GABA were observed within 3 min after death, as reported by other researchers.
D000596:Amino Acids / Q000032:analysis; D021542:Amino Acids, Neutral; D015119:Aminocaproic Acid / Q000032:analysis; D000818:Animals; D001923:Brain Chemistry; D004355:Drug Stability; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D051379:Mice; D008813:Mice, Inbred ICR; D011180:Postmortem Changes; D051381:Rats; D011919:Rats, Inbred Strains; D012663:Semicarbazides / Q000494:pharmacology; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
D000596:Amino Acids; D021542:Amino Acids, Neutral; D012663:Semicarbazides; D005680:gamma-Aminobutyric Acid; C013809:5-aminovaleric acid; D015119:Aminocaproic Acid