Developmental changes of N-acetyl-L-aspartic acid, N-acetyl-alpha-aspartylglutamic acid and beta-citryl-L-glutamic acid in different brain regions and spinal cords of rat and guinea pig.

The developmental changes of N-acetylaspartic acid (NA-Asp), N-acetyl-alpha-aspartylglutamic acid (NA-Asp-Glu), and beta-citryl-L-glutamic acid (beta-CG) have been examined in the cerebrum, cerebellum, brain stem and spinal cord of both rat and guinea pig by the gas chromatographic method developed in our studies. A rapid increase in the concentration of NA-Asp was observed postnatally in every region of the rat brain. On the other hand, all regions of guinea pig brain showed the prenatal increases. NA-Asp-Glu showed a different developmental profile, depending on region of the brain, in the two species. The concentration of NA-Asp-Glu remained constantly low during brain maturation in the rostral regions. In the caudal portions it showed a marked increase during maturation and reached a high level in the adult brain. The concentration of beta-CG was highest at birth in all regions of rat brain and rapidly decreased by 20 days after birth and remained low thereafter. The rapid decrease occurred in the guinea pig during the foetal period, and beta-CG content decreased to an adult level at birth.