BASIC ASPECTS OF GABA-TRANSAMINASE IN NEUROPSYCHIATRIC DISORDERS

Over the last two decades, there have been several studies suggesting the major inhibitory amino acid neurotransmitter gamma-aminobutyric ac id (GABA) is involved directly and/or indirectly in the pathogensis of many neurologic diseases and psychiatric disorders. GABA is mainly de gradated to succinic semialdehyde in a reaction catalyzed by the enzym e GABA-transaminase (GABA-T). Inhibition of this enzyme produces consi derable elevation of GABA contents in the brain, and such elevation ha s been found to correlate with pharmacologic and behavioral effects. W e focus attention, from the basic aspects, on brain and platelet GABA- T activities in various species, with a special reference to neuropsyc hiatric disorders. It seems that the activity of GABA-T in the brain a nd/or in the blood platelets is correlated to certain neuropsychiatric disorders such as alcoholism, epilepsy, and Alzheimer's disease. In a nimal and human studies, platelet GABA-T was identified with similar k inetic and inhibitor characteristics to those of the brain. Therefore, in this way, studies of the activity of the enzyme GABA-T in relation to neuropsychiatric disorders could be undertaken to understand, diag nose, and treat GABA-related disorders of the central nervous system.