A Gas Chromatographic Method for the Determination of N‐Acetyl‐l‐Aspartic Acid, N‐Acetyl‐α‐ Aspartylglutamic Acid and β‐Citryl‐l‐Glutamic Acid and Their Distributions in the Brain and Other Organs of Various Species of Animals

Abstract: A simple and sensitive gas‐chromatographic method for the determination of N‐acetyl‐l‐aspartic acid (NA‐Asp), N‐acetyl‐α‐aspartylglutamic acid (NA‐Asp‐Glu) and β‐citryl‐l‐glutamic acid (β‐CG) was developed. The organ, regional and phylogenetic distributions of these compounds were studied. NA‐Asp and NA‐Asp‐Glu were highly concentrated in nervous tissue, and less than 1% of the amounts in the nervous tissues were found in nonnervous organs. These two compounds showed a reciprocal relationship in their regional distribution in mature brains, but such a relationship was not evident or was even reversed in immature brains. The two compounds also showed different developmental changes in different regions of the brain. Fish brain contained a relatively high concentration of NA‐Asp, but only a trace amount of NA‐Asp‐Glu. By contrast, a 10 times higher concentration of NA‐Asp‐Glu than NA‐Asp was found in frog brain. Reptilian brain contained similar amounts of each compound. Avian and mammalian brain had NA‐Asp at a roughly 10 times higher concentration than NA‐Asp‐Glu. β‐CG occurred at the highest concentration in the immature brain of rat and guinea pig, but disappeared in the mature brains. The adult frog brain, however, contained a large amount of β‐CG. In the adult rat, testis contained the highest concentration of β‐CG.