Centrally-acting drugs and the formation of brain gamma-aminobutyric acid.

1. The effects of a number of centrally-acting compoinds were tested on the levels of GABA and glutamate and on the formation of GABA from glutamate in rat brain. 2. Pargyline and desipramine increased the brain concentration of GABA but were without effect on GABA production. 3. Imidazoleacetic acid increased GABA levels, decreased glutamate levels but did not alter GABA production, whereas gamma-hydroxybutyric acid had an effect only on GABA formation. 4. Isonicotinc acid hydrazine caused a marked decrease in the formation of GABA from glutamate. 5. Chlorpromazine, diphenylhydantoin, bicucculine, and L-DOPA had no effect on any of the biochemical parameters measured. 6. The central effects of these drugs are discussed in relation to the above findings.