Rapid assessment of in vivo cholinergic transmission by amperometric detection of changes in extracellular choline levels

Vinay Parikh, Francois Pomerleau, Peter Huettl, Greg A. Gerhardt, Martin Sarter, John P. Bruno

Research output: Contribution to journalArticlepeer-review

101 Scopus citations


Conventional microdialysis methods for measuring acetylcholine (ACh) efflux do not provide sufficient temporal resolution to relate cholinergic transmission to individual stimuli or behavioral responses, or sufficient spatial resolution to investigate heterogeneities in such regulation within a brain region. In an effort to overcome these constraints, we investigated a ceramic-based microelectrode array designed to measure amperometrically rapid changes in extracellular choline as a marker for cholinergic transmission in the frontoparietal cortex of anesthetized rats. These microelectrodes exhibited detection limits of 300 nM for choline and selectivity (> 100 : 1) of choline over interferants such as ascorbic acid, Intracortical pressure ejections of choline (20 mM, 66-400 nL) and ACh (10 and 100 mM, 200 nL) dose-dependently increased choline-related signals that were cleared to background levels within 10 s. ACh, but not choline-induced signals, were significantly attenuated by co-ejection of the acetylcholinesterase inhibitor neostigmine (Neo; 100 mw). Pressure ejections of drugs known to increase cortical ACh efflux, potassium (KCl; 70 mM, 66, 200 nL) and scopolamine (Scop; 10 mM, 200 nL), also markedly increased extracellular choline signals, which again were inhibited by Neo. Scop-induced choline signals were also found to be tetrodotoxin-sensitive. Collectively, these findings suggest that drug-induced increases in current measured with these microelectrode arrays reflect the oxidation of choline that is neuronally derived from the release and subsequent hydrolysis of ACh. Choline signals assessed using enzyme-selective microelectrode arrays may represent a rapid, sensitive and spatially discrete measure of cholinergic transmission.

Original languageEnglish
Pages (from-to)1545-1554
Number of pages10
JournalEuropean Journal of Neuroscience
Issue number6
StatePublished - Sep 2004


  • Acetylcholine
  • Frontoparietal cortex
  • Microelectrode arrays
  • Rat

ASJC Scopus subject areas

  • Neuroscience (all)


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