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Anatomical Distribution and Postnatal Changes in Endogenous Free D‐Aspartate and D‐Serine in Rat Brain and Periphery

We have investigated the anatomical distribution and postnatal development of D‐aspartate and D‐serine in the rat brain and periphery using HPLC techniques. D‐Serine was confined predominantly to the brain throughout postnatal life. At birth, a substantial quantity of D‐serine was observed throughout the brain areas. The cerebral D‐serine content increased from birth to postnatal week (PW) 3 and remained constant thereafter, whereas the cerebellar D‐serine content peaked at PW1. In contrast, the transient emergence of D‐aspartate was found in almost all brain and peripheral organs. A substantial quantity of D‐aspartate was also seen in all brain areas at birth, whereas the D‐aspartate content in the cerebrum and cerebellum decreased dramatically by PW1 and 7 respectively. Further, the D‐aspartate content and the ratio of D‐aspartate to total aspartate were highest in the adrenal at PW3 (608 ± 70 nmol/g, 45.9%) and in the testis at PW14 (221 ± 7 nmol/g, 57.8%) respectively. Because D‐serine potentiates N‐methyl‐D‐aspartate receptor‐mediated transmission through the strychnine‐insensitive glycine site and because D‐serine exhibits an N‐methyl‐D‐aspartate receptor‐related distribution and development, D‐serine may be a tenable candidate for an intrinsic ligand for the glycine site. In contrast, because the periods of maximal emergence of D‐aspartate in the brain and periphery occur during critical periods of morphological and functional maturation of organs, D‐aspartate could participate in the regulation of these developmental processes of organs.