Regional Distribution of Amino Acids in Human Brain Obtained at Autopsy

Abstract— Contents (μmol/g wet wt.) of 35 free amino acids and related compounds were measured in 12 different regions of each of five human brains. Specimens were obtained at autopsy from patients who died suddenly without previous brain disease. These data may serve for later comparison with contents of amino compounds in similar regions of the brains of patients dying with various neurological or psychiatric disorders. There were marked and consistent differences in the regional distribution of the following eight compounds: γ‐aminobutyric acid, homocarnosine, glutamic acid, aspartic acid, taurine, cystathionine, glycerophosphoethanolamine, and phosphoethanolamine. These differences suggest that some of these compounds may have special physiological roles, including the possible mediation of synaptic transmission. Human brain contains two previously unreported compounds, the mixed disulphide of cysteine and glutathione and α‐(γ‐aminobutyryl)‐lysine. The latter dipeptide occurs in much higher concentrations in human brain than in the brains of lower mammals.