Characterization of a yeast D-amino acid oxidase microbiosensor for D-serine detection in the central nervous system.
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.
Pernot
Pierre
P
CNRS, Institut de Neurobiologie Alfred Fessard-FRC2118, Laboratoire de Neurobiologie Cellulaire et Moléculaire-UPR9040, 91198 Gif sur Yvette, France.
Mothet
Jean-Pierre
JP
Schuvailo
Oleg
O
Soldatkin
Alexey
A
Pollegioni
Loredano
L
Pilone
Mirella
M
Adeline
Marie-Thérèse
MT
Cespuglio
Raymond
R
Marinesco
Stéphane
S
D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002490:Central Nervous System / Q000737:chemistry / Q000378:metabolism*; D003605:D-Amino-Acid Oxidase / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008839:Microelectrodes; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D012248:Rhodotorula / Q000201:enzymology*; D012694:Serine / Q000032:analysis* / Q000378:metabolism; D013696:Temperature
D012694:Serine; D003605:D-Amino-Acid Oxidase; D010100:Oxygen