γ‐AMINOBUTYRIC ACID (GABA) IN THE RAT BRAIN: RE‐EVALUATION OF SAMPLING PROCEDURES AND THE POST‐MORTEM INCREASE1

Abstract

Abstract—GABA levels determined after the brain was removed, then frozen, were found to be generally compatible to levels after the brain was frozen in situ provided removal and freezing were effected in less than 60 s. Optimal GABA values were realized when the brain was removed and frozen in liquid nitrogen within 30 s of death. Beginning at 60 s post‐mortem, GABA levels increased until the 4th min with the greatest rate occurring between 60 and 120 s at 30 μg/g/min. When frozen brains were dissected into regions by a partial thawing technique, post‐mortem increases were not found to occur. Microwave irradiation, investigated as a potential sampling technique for GABA assay, showed considerable variability between samples and was rejected as a practical alternative at this time.