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Levels of free amino acids were determined quantitatively in whole ocular tissues of the rat eye with aid of a sensitive amino acid analyzer. The tissues studied were the retina, vitreous, lens, iris-ciliary body, and cornea. The retina and lens contained a more concentrated free amino acid pool than other tissues. The neuroactive amino acids taurine. GABA, glutamic acid, aspartic acid, and glycine were clearly enriched in the retina. Taurine was the most abundant amino acid in all five tissues studied, and its high concentration in non-neural tissues, especially the lens, suggests that it must have other functions as well as neurotransmitter ones in the rat eye.

Abstract— dl‐Allylglycine, a potent inhibitor of glutamate decarboxylase in vivo when given intraperitoneally, causes a marked decrease in brain GABA concentration and at the same time a dramatic increase in l‐ornithine decarboxylase activity and a simultaneous decrease in S‐adenosyl‐l‐methionine decarboxylase activity followed by putrescine accumulation. It does not, however, alter the degree of GABA formation from putrescine. The timing of the recovery of glutamate decarboxylase activity after the injection of dl‐allylglycine is concomitant with that of the GABA concentration, indicating that it is probably glutamate decarboxylase that is solely responsible for making up the GABA deficit caused by dl‐allylglycine, and that the changes in polyamine metabolism are associated in some indirect way with the recovery process.