DIFFERENTIAL EFFECTS OF AGONAL STATUS ON MEASUREMENTS OF GABA AND GLUTAMATE-DECARBOXYLASE IN HUMAN POSTMORTEM BRAIN-TISSUE FROM CONTROL AND HUNTINGTONS-CHOREA SUBJECTS

Abstract— GABA and its biosynthetic enzyme glutamic acid decarboxylase (GAD) remained remarkably stable for many hours after death in both human putamen obtained at autopsy and in mouse brain stored under conditions simulating the routine handling of human cadavers. GAD activity was profoundly influenced by agonal status in control but not in choreic subjects. Conversely, GABA concentrations were unaffected by the agonal status but showed a significant age‐related decline. GAD activity and GABA concentrations were positively correlated in sudden death control cases but not in control cases suffering a protracted terminal illness or in choreic subjects. In choreic putamen there was an approximate 50% reduction in GABA concentration and GAD activity (correcting for agonal status) consistent with the hypothesis that striatal GABA‐containing neurones degenerate in this disease. Since GABA concentrations are unaffected by agonal factors they may provide a reliable marker for the integrity of GABA systems provided that control and pathological groups are matched for age and delay in post‐mortem sampling. Copyright © 1979, Wiley Blackwell. All rights reserved