Web Release Date: January 30,
Characterization of a Yeast D-Amino Acid Oxidase Microbiosensor for D-Serine Detection in the Central Nervous System
and
CNRS, Institut de Neurobiologie Alfred Fessard-FRC2118, Laboratoire de Neurobiologie Cellulaire et Moléculaire-UPR9040, 91198 Gif sur Yvette, France, Institut National de la Santé et de la Recherche Médicale U862, Université Bordeaux 2, Institut Magendie, 146 rue Léo Saignat, 33077 Bordeaux, France, EA4170, Université Claude Bernard Lyon I, 8 avenue Rockefeller, 69373 Lyon, France, Institute of Molecular Biology and Genetics, National Academy of Science of Ukraine, 150 zabolotny Str, 03143 Kiev, Ukraine, Department of Biotechnology and Molecular Sciences, University of Insubria, Varese, Italy, CNRS, Institut de Chimie des Substances Naturelles, 91198 Gif sur Yvette, France, and Institut National de la Santé et de la Recherche Médicale U628, Université Claude-Bernard-Lyon I, 8 avenue Rockefeller, 69373 Lyon Cedex 08, France
Received for review October 29, 2007. Accepted December 9, 2007.
Abstract:
D-Serine is an endogenous ligand for N-methyl-D-aspartate (NMDA) receptors, and alterations in its concentration have been related to several brain disorders, especially schizophrenia. It is therefore an important target neuromodulator for the pharmaceutical industry. To monitor D-serine levels in vivo, we have developed a microbiosensor based on cylindrical platinum microelectrodes, covered with a membrane of poly-m-phenylenediamine (PPD) and a layer of immobilized D-amino acid oxidase from the yeast Rhodotorula gracilis (RgDAAO). By detecting the hydrogen peroxide produced by enzymatic degradation of D-serine, this microbiosensor shows a detection limit of 16 nM and a mean response time of 2 s. Interferences by ascorbic acid, uric acid, L-cysteine, and by biogenic amines and their metabolites are rejected at more than 97% by the PPD layer. Although several D-amino acids are potential substrates for RgDAAO, D-serine was the only endogenous substrate present in sufficient concentration to be detected by our microbiosensor in the central nervous system. When implanted in the cortex of anesthetized rats, this microbiosensor detected the increase in concentration of D-serine resulting from its diffusion across the blood-brain barrier after an intraperitoneal injection. This new device will make it possible to investigate in vivo the variations in D-serine concentrations occurring under normal and pathological conditions and to assess the pharmacological potency of new drugs designed to impact D-serine metabolism.
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