Free Amino Acids and Related Compounds in Brain and Other Tissues: Effects of Convulsant Drugs

Abstract

Publisher Summary This chapter summarizes a series of studies on free amino acids and related compounds in the brain. Cerebral tissue was analyzed by ion-exchange chromatography and other methods, and the technique of freezing the brain in situ with liquid air was used to avoid post-mortem increases that otherwise occur in alanine, ammonia, γ-aminobutyric acid and lactic acid. Dogs were used for most of the experiments, but supplemental studies on the effects of fluoro compounds in mice are included in the chapter. Anoxia induced by the administration of 4.5% oxygen in nitrogen for 12–13 min brought about significant increase in alanine, y-aminobutyric acid, glutamic acid, lactic acid, leucine, and tyrosine and decrease in aspartic acid and a fraction consisting of methionine and cystathionine. Ammonia was not significantly increased. Infusion of buffered ammonium chloride for a 10 min or 45 min period generally caused some degree of depression of cortical electrical activity, although in one animal a seizure developed. Amino-oxyacetic acid, which is known to antagonize the convulsant actions of thiosemicarbazide and methionine sulfoximine, was found to induce increase in brain γ-aminobutyrate, alanine, ammonia, glutamine, lactate, lysine, and tyrosine and a decrease in aspartate. Methionine sulfoximine was found to have extensive effects on the nitrogenous metabolism of the brain, causing increases in alanine, ammonia, lysine, phosphoethanolamine, and serine and decrease in aspartate, glutamate, glutamine, leucine, and the methionine and cystathionine fraction.