ラット唾液腺におけるD-アスパラギン酸の存在

抄録

Amino acids in mammalian tissues and body fluids have been considered to consist solely of L-enantiomer. However, the recent studies have reported the presence of several free D-amino acids, exclusively D-serine (D-Ser) and D-aspartic acid (D-Asp), in mammalian tissues. D-Ser specifically exists in the brain and plays a genuine ligand for NMDA receptor. The high concentration of D-Asp was found in rat pituitary gland, pineal gland, adrenal gland and testis. These suggest that free D-amino acids may play some important roles in mammals.
The present study was arranged to investigate the occurrence of D-Asp in rat salivary glands by using a high-performance liquid chromatography technique. The concentration of D-Asp was high in the parotid gland (PG) (0.212±0.068μmol/g) and the submandibular gland (SMG) (0.233±0.034μmol/g) of 7-week-old rats, but the low in the sublingual gland (0.038±0.020μmol/g). A transient increase of D-Asp concentration was observed in 3-week-old rat PG. On the other hand, D-Asp content in the SMG was held at a high level in and after 7-week-old. These results suggested that free D-Asp may play different roles in rat PG and SMG.