Neuroscience 2002 Abstract
| Presentation Number: | 446.15 |
|---|---|
| Abstract Title: | DESCENDING FACILITATION OF SPINAL MOTONEURON ACTIVITY IN THE ISOLATED BRAINSTEM AND SPINAL CORD OF THE NEONATAL RAT. |
| Authors: |
Gilmore, J.*1
; Fedirchuk, B.1
1Physiol, University of Manitoba, Winnipeg, Canada |
| Primary Theme and Topics |
Synaptic Transmission and Excitability - Intrinsic Membrane Properties -- Modulation of intrinsic membrane properties |
| Secondary Theme and Topics | Motor Systems<br />- Motoneurons |
| Session: |
446. Intrinsic membrane properties: modulation II Poster |
| Presentation Time: | Tuesday, November 5, 2002 10:00 AM-11:00 AM |
| Location: | Hall A2-B3 E-65 |
| Keywords: | locomotion, neuromodulation, ACTION POTENTIAL, MONOAMINE |
It has been shown that the excitability of cat spinal motoneurons increases during fictive locomotion by lowering the voltage threshold (Vth) for action potential production (Krawitz et al. 2001, J Physiol 532, 271-281). This facilitation of motoneuron recruitment is not directly linked to phasic depolarizations during the step cycle. Rather, it appears to be a state-dependent enhancement of motoneuron excitability, presumably due to a neuromodulatory system. We have also shown that exogenously applied serotonin is able to hyperpolarize the Vth of spinal neurons in the neonatal rat in the absence of locomotor-activity (Fedirchuk 2001, SFN Vol 27, 714.17). The goals of the present series of experiments are to show that activation of locomotor circuitry can cause a lowering of Vth in spinal motoneurons of the neonatal rat, and determine if serotonin is the endogenous neurotransmitter mediating this phenomenon.
Experiments were conducted on neonatal (P0-P5) rats that were anaesthetized and decerebrated. The brainstem and spinal cord were then removed and perfused with oxygenated aCSF in a recording chamber. Motor output was monitored from recordings of lumbar ventral roots, and initiated by stimulation of the brainstem or spinal white matter. The excitability of lumbar motoneurons was assessed by single cell recordings using a whole-cell blind patch technique. Antagonists to receptors of the descending serotonergic system were selectively applied to the spinal bath, and their ability to block motoneuron Vth changes assessed.
Experiments were conducted on neonatal (P0-P5) rats that were anaesthetized and decerebrated. The brainstem and spinal cord were then removed and perfused with oxygenated aCSF in a recording chamber. Motor output was monitored from recordings of lumbar ventral roots, and initiated by stimulation of the brainstem or spinal white matter. The excitability of lumbar motoneurons was assessed by single cell recordings using a whole-cell blind patch technique. Antagonists to receptors of the descending serotonergic system were selectively applied to the spinal bath, and their ability to block motoneuron Vth changes assessed.
Supported by Canadian Institutes of Health Research/Canadian Neurotrauma Research Program.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2002 Neuroscience Meeting Planner. Orlando, FL: Society for Neuroscience, 2002. Online.
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