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This Article Full Text Full Text (PDF) All Versions of this Article: 92/3/1536    most recent 01053.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Quinlan, K. A. Articles by Buchanan, J. T. Search for Related Content PubMed PubMed Citation Articles by Quinlan, K. A. Articles by Buchanan, J. T.

Cholinergic Modulation of the Locomotor Network in the Lamprey Spinal Cord

Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201

Submitted 30 October 2003; accepted in final form 9 May 2004

Acetylcholine (ACh) was found here to be a strong modulator of swimming activity in the isolated spinal cord preparation of the adult lamprey (Ichthyomyzon unicuspis). During fictive swimming induced with either D-glutamate or N-methyl-D-aspartate, addition of ACh (200 µM) significantly reduced the cycle period of ventral root bursts to 54%, intersegmental phase lag to 32%, and ventral root burst proportion to 80% of control levels. Effects of ACh were apparent at concentrations as low as 1 µM. Both nicotinic and muscarinic receptors are involved, in that application of either nicotinic or muscarinic agonists alone significantly reduced cycle period. There is sufficient endogenous ACh in the spinal cord to modulate ongoing fictive swimming, as shown by application of the cholinesterase inhibitor eserine (physostigmine). Eserine (20 µM) significantly reduced the cycle period to 78% and phase lag to 58% of control levels, and these effects were reversed with the addition of cholinergic blockers. Addition of only a nicotinic or muscarinic antagonist, mecamylamine (10 µM) or scopolamine (20 µM), respectively, to the spinal cord during fictive swimming produced significant increases in cycle period and phase lag, suggesting that both types of cholinergic receptors participate in endogenous cholinergic modulation. It is concluded that ACh is an endogenous modulator of the locomotor network in the lamprey spinal cord and that ACh may take part in the regulation of cycle period, intersegmental coupling, and ventral root burst duration.

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