Biological actions in vivo and in vitro of two gamma-aminobutyric acid (GABA) analogues: beta-chloro GABA and beta-phenyl GABA.

1 The synthesis of two analogues of gamma-aminobutyric acid (GABA), beta-chloro GABA and beta-phenyl GABA is described.2 The activity of brain GABA aminotransferase was inhibited by beta-chloro GABA (5.7 x 10(-5)M) and beta-phenyl GABA (4.6 x 10(-3)M) in a competitive manner with GABA.3 beta-Chloro GABA exhibited 50% of the inhibitory activity of GABA in blocking the discharge of the crayfish stretch receptor neurone; beta-phenyl GABA had no detectable effect.4 Injection of beta-phenyl GABA (200 mg/kg) into normal or epileptic cats (cobalt) caused the appearance of synchronized slow-wave EEG activity.5 Administration of beta-chloro GABA (200 mg/kg) to epileptic cats (cobalt) produced a temporary diminution or abolition of epileptic discharges while causing no alteration in normal EEG activity.6 beta-Chloro GABA and beta-phenyl GABA had no effect on the concentrations of catecholamines or of amino acids in mouse brain.7 The results suggest that both beta-chloro GABA and beta-phenyl GABA may pass the blood-brain barrier.