Elevation of hippocampal extracellular acetylcholine levels by methoctramine

Michael J. Stillman, Barbara Shukitt-Hale, Roberto M. Kong, Aharon Levy, Harris R. Lieberman

Research output: Contribution to journalArticlepeer-review


Previous studies suggest that m2 muscarinic receptors serve as presynaptic autoreceptors. Blocking these receptors by selective antagonists may, therefore, lead to increased acetylcholine (ACh) release. This study assessed changes in extracellular ACh levels, via in vivo microdialysis, following administration of the m2 antagonist methoctramine. Drug or placebo (Ringer's solution) was perfused via a microdialysis probe into the CA1 hippocampal region of unrestrained, awake male Fischer rats. HPLC-EC was used for online analysis of the dialysates. Methoctramine significantly enhanced ACh release in a dose-dependent fashion as compared to placebo for the doses employed (0.25-16 μM). The present in vivo data corroborate studies that show increased ACh levels in vitro following application of m2 antagonists.

Original languageEnglish
Pages (from-to)385-389
Number of pages5
JournalBrain Research Bulletin
Issue number4
StatePublished - 1993
Externally publishedYes


  • Acetylcholine
  • Autoreceptor
  • Methoctramine
  • Microdialysis
  • Muscarinic receptors m
  • Receptor


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