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d-Amino acid oxidase and serine racemase in human brain: normal distribution and altered expression in schizophrenia
Article first published online: 14 SEP 2007
European Journal of Neuroscience
Volume 26, Issue 6, pages 1657–1669, September 2007
How to Cite
Verrall, L., Walker, M., Rawlings, N., Benzel, I., Kew, J. N. C., Harrison, P. J. and Burnet, P. W. J. (2007), d-Amino acid oxidase and serine racemase in human brain: normal distribution and altered expression in schizophrenia. European Journal of Neuroscience, 26: 1657–1669. doi: 10.1111/j.1460-9568.2007.05769.x
- Issue published online: 14 SEP 2007
- Article first published online: 14 SEP 2007
- Received 24 October 2006, revised 13 June 2007, accepted 11 July 2007
The N-methyl-d-aspartate receptor co-agonist d-serine is synthesized by serine racemase and degraded by d-amino acid oxidase. Both d-serine and its metabolizing enzymes are implicated in N-methyl-d-aspartate receptor hypofunction thought to occur in schizophrenia. We studied d-amino acid oxidase and serine racemase immunohistochemically in several brain regions and compared their immunoreactivity and their mRNA levels in the cerebellum and dorsolateral prefrontal cortex in schizophrenia. d-Amino acid oxidase immunoreactivity was abundant in glia, especially Bergmann glia, of the cerebellum, whereas in prefrontal cortex, hippocampus and substantia nigra, it was predominantly neuronal. Serine racemase was principally glial in all regions examined and demonstrated prominent white matter staining. In schizophrenia, d-amino acid oxidase mRNA was increased in the cerebellum, and as a trend for protein. Serine racemase was increased in schizophrenia in the dorsolateral prefrontal cortex but not in cerebellum, while serine racemase mRNA was unchanged in both regions. Administration of haloperidol to rats did not significantly affect serine racemase or d-amino acid oxidase levels. These findings establish the major cell types wherein serine racemase and d-amino acid oxidase are expressed in human brain and provide some support for aberrant d-serine metabolism in schizophrenia. However, they raise further questions as to the roles of d-amino acid oxidase and serine racemase in both physiological and pathophysiological processes in the brain.