Changes in brain γ-aminobutyric acid concentrations following acute and chronic amphetamine administration and during post amphetamine depression

Abstract

The acute administration of d-amphetamine caused an increase in the γ-aminobutyric acid (GABA) content of the brain stem and thalamus. Acute chloropromazine treatment lowered the GABA concentration in the thalamus, olfactory lobes and brain stem. Although this neuroleptic antagonized the stereotypy induced by amphetamine, drug combination markedly increased the GABA content of all brain regions studied. Following the chronic administration of amphetamine for 2 weeks, the GABA content of the striatum and thalamus decreased even though the stereotyped behaviour was more marked than that occurring after acute amphetamine administration. During the period of post amphetamine depression, the GABA content of the striatum and brain stem were also decreased whereas that of the amygdala was increased. These studies suggest that the changes in the GABA content do not reflect changes in gross behaviour following amphetamine administration. Nevertheless, they do suggest that the inhibitory amino acid may play an ancillary role in determining the neuropharmacological profile of amphetamine.