Microelectrode array studies of basal and potassium-evoked release of L-glutamate in the anesthetized rat brain

B. K. Day, F. Pomerleau, J. J. Burmeister, P. Huettl, G. A. Gerhardt

Research output: Contribution to journalArticle

135 Scopus citations

Abstract

L-glutamate (Glu) is the predominant excitatory neurotransmitter in the mammalian central nervous system. It plays major roles in normal neurophysiology and many brain disorders by binding to membrane-bound Glu receptors. To overcome the spatial and temporal limitations encountered in previous in vivo extracellular Glu studies, we employed enzyme-coated microelectrode arrays to measure both basal and potassium-evoked release of Glu in the anesthetized rat brain. We also addressed the question of signal identity, which is the predominant criticism of these recording technologies. In vivo self-referencing recordings demonstrated that our Glu signals were both enzyme- and voltage-dependent, supporting the identity of l-glutamate. In addition, basal Glu was actively regulated, tetrodotoxin (TTX)-dependent, and measured in the low micromolar range (approximately 2 μM) using multiple self-referencing subtraction approaches for identification of Glu. Moreover, potassium-evoked Glu release exhibited fast kinetics that were concentration-dependent and reproducible. These data support the hypothesis that Glu release is highly regulated, requiring detection technologies that must be very close to the synapse and measure on a second-by-second basis to best characterize the dynamics of the Glu system.

Original languageEnglish
Pages (from-to)1626-1635
Number of pages10
JournalJournal of Neurochemistry
Volume96
Issue number6
DOIs
StatePublished - Mar 1 2006
Externally publishedYes

Keywords

  • Amperometry
  • Electrochemistry
  • Neurochemical
  • Neurotransmitter
  • Voltammetry

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