INFLUENCE OF EXCESS METHIONINE ON FREE AMINO ACIDS OF BRAIN AND LIVER OF WEANLING RAT

Abstract— —High circulating levels of l‐methionine produced by inclusion in the diet or parenteral injection of the amino acid caused alterations in the free amino acid pattern of liver and brain tissues. Acute effects following l‐methionine injection were more pronounced than those following long term feeding where adaptation played a role. The net effect following parenteral injection was to increase the total free amino acids of liver while decreasing those of brain. Individually, hepatic levels of aspartic acid, threonine, serine, glutamine, glutamic acid, glycine, and alanine were depressed while levels of taurine, cystathionine, methionine, lysine, and ornithine were markedly elevated. Brain levels of aspartic acid, threonine, serine, glutamic acid, glycine, alanine, and γ‐aminobutyric acid were markedly depressed and increased levels of cystathionine, methionine, lysine, and glutamine were observed. A generalized aminoaciduria occurred shortly after excessive methionine intake. Disruption of the free amino acid pools was of two kinds. The first depended on the continued presence of excess l‐methionine, the second did not. Copyright © 1969, Wiley Blackwell. All rights reserved