Distribution of GABA in post-mortem brain tissue from control, psychotic and Huntington's chorea subjects.

Gamma-aminobutyric acid (GABA) concentrations were measured in 10 regions of post-mortem brain from control, psychotic and choreic subjects; glutamate decarboxylase (GAD) activities were estimated in substantia nigra. In agreement with earlier observations, agonal status profoundly affected GAD measurements in the substantia nigra but had no effect on GABA levels in any brain region. Although GAD and GABA levels were significantly correlated in nigral tissue from sudden death control and psychotic cases, the association was lost in patients dying slowly. In Huntington's chorea significant reduction in GABA content were observed in the nucleus accumbens, lateral pallidum, subthalamic nucleus, substantia nigra and ventrolateral thalamic nucleus. In psychotic patients there were significant decreases in GABA concentrations in the amygdala and nucleus accumbens. Division of the psychotic group into schizophrenia and schizophrenia-like categories and into early-onset and later-onset cases revealed that GABA levels in the amygdala were diminished in all 4 psychotic subgroups, whereas in the nucleus accumbens the deficit was confined to cases of early-onset schizophrenia.