The significance of ammonia/gamma-aminobutyric acid (GABA) ratio for normality and liver disorders

• Published in: Medical hypotheses Vol. 59; no. 6; pp. 757 - 758
• Main Author: Cohen, Brett I
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.12.2002
• Subjects: 4-Aminobutyrate Transaminase - metabolism; Ammonia - metabolism; Autistic Disorder - etiology; gamma-Aminobutyric Acid - metabolism; Humans; Liver - metabolism; Liver Diseases - metabolism; Models, Biological
• ISSN: 0306-9877; 1532-2777
• DOI: 10.1016/S0306-9877(02)00325-0

Cohen (1,2) has illustrated that extremely high Gamma-aminobutyric acid (GABA) levels in the urine and blood and high plasma ammonia were observed for an autistic male child diagnosed with infantile autism. GABA is a major inhibitory neurotransmitter of the mammalian brain and the enzyme responsible for catabolism is GABA-Transaminase (GABA-T). Elevated levels of ammonia in the plasma results in a decrease in the efficiency for the GABA-T enzyme and this results in higher GABA concentrations after regulation in the liver. It is postulated that a link between plasma ammonia and plasma GABA exists where the concentration of GABA in the plasma is directly related to the ammonia plasma concentration. A ratio of approximately 0.30 (plasma ammonia/GABA) is a consistent finding for normal subjects and for subjects with infantile autism and liver diseases such as hepatic encephalopathy.