Determination of free d-aspartic acid, d-serine and d-alanine in the brain of mutant mice lacking d-amino-acid oxidase activity

A simple and precise method for the simultaneous determination of free d-aspartic acid, d-serine and d-alanine in mouse brain tissues was established, using a reversed-phase HPLC system with widely used pre-column derivatizing reagents, o-phthaldialdehyde and N-t-butyloxycarbonyl-l-cysteine. With the present method, the contents of these three d-amino acids in hippocampus, hypothalamus, pituitary gland, pineal gland and medulla oblongata as well as cerebrum and cerebellum of mutant mice lacking d-amino-acid oxidase activity were determined and compared with those obtained for control mice. In both mice, extremely high contents of d-serine were observed in forebrain (100–400 nmol/g wet tissue), and the contents were small in pituitary and pineal glands. While, d-serine contents in cerebellum and medulla oblongata of mutant mice were about ten times higher than those in control mice. In contrast, d-alanine contents in mutant mice were higher than those in control mice in all brain regions and serum.