title: Rapid assay for gamma-aminobutyric acid in mouse brain synaptosomes using gas chromatography-mass spectrometry.
abstract: A sensitive and efficient assay for gamma-aminobutyric acid (GABA) was applied to fresh mouse whole brain synaptosomes where the extracted GABA was analyzed as its di(tert.-butyl(dimethylsilyl)) derivative by gas chromatography-mass spectrometry (GC-MS) using GABA-d6 as an internal standard. Endogenous levels of 20.01 +/- 0.75 nmol GABA/mg protein were found. The method is characterized by a detection limit of about 10 fmol injected GABA derivative and coefficients of intra-day and inter-day variation of 0.95% and 7.7%, respectively. The rate of synaptosomal GABA synthesis was used to determine the activity of glutamate decarboxylase (GAD) as 314.9 +/- 9.0 nmol GABA/mg protein/h. Both GABA levels and GAD activity were significantly elevated by therapeutic doses of the antiepileptic drug valproic acid.
authors.affiliation: Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Palaty
authors.forename: R
authors.initials: R
authors.lastname: Burton
authors.forename: F S
authors.initials: FS
authors.lastname: Abbott
mesh_terms: D000081:Acetamides; D000818:Animals; D001921:Brain / Q000648:ultrastructure; D001923:Brain Chemistry / Q000187:drug effects*; D005463:Fluoroacetates; D008401:Gas Chromatography-Mass Spectrometry; D005968:Glutamate Decarboxylase / Q000378:metabolism; D007202:Indicators and Reagents; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000201:enzymology; D013574:Synaptosomes / Q000737:chemistry* / Q000187:drug effects; D014297:Trimethylsilyl Compounds; D014635:Valproic Acid / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
chemical_list: D000081:Acetamides; D005463:Fluoroacetates; D007202:Indicators and Reagents; D014297:Trimethylsilyl Compounds; C086665:N-methyl-N-(trimethylsilyl)trifluoroacetamide; D005680:gamma-Aminobutyric Acid; D014635:Valproic Acid; D005968:Glutamate Decarboxylase