Decreased glutamic acid and increased 5-hydroxytryptamine in Huntington's disease brain.

gamma-Aminobutyric acid (GABA), glutamate and serotonin (5-HT), along with its major metabolite, 5-hydroxyindoleacetic acid (5-HIAA), have been measured in 4 brain regions taken post-mortem from patients with Huntington's disease and from control subjects. GABA was found to be significantly reduced, not only in the basal ganglia, but also in the cortex and hippocampus. Glutamate was also reduced in all regions except the pallidum, and thus was unrelated to the GABA deficit which was greatest in this area. 5-HT and 5-HIAA were significantly increased in all areas except the hippocampus.