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Effects of exercise training on alpha-motoneurons
P Gardiner1, Y Dai, C J Heckman
1Department of Physiology, Spinal Cord Research Center, University of Manitoba, 730 William Ave., Winnipeg, Manitoba, Canada R3E 3J7. gardine2@cc.umanitoba.ca
Journal of Applied Physiology (Bethesda, Md. : 1985)
|June 17, 2006
Summary
Exercise training alters alpha-motoneurons, enhancing their function through structural and electrophysiological changes. These adaptations in neural pathways may involve ion channel modifications, impacting motoneuron excitability.
Area of Science:
- Neuroscience
- Exercise Physiology
- Cellular Biology
Background:
- Neural adaptations to training are crucial for improved motor function.
- Alpha-motoneurons play a key role in voluntary muscle activation and motor control.
Purpose of the Study:
- To investigate the specific adaptations occurring at the alpha-motoneuron level due to exercise training.
- To model and understand the electrophysiological changes in motoneurons following training.
Main Methods:
- Analysis of cellular changes in alpha-motoneurons with increased voluntary activity.
- Development and utilization of a computational model of rat motoneurons (five-compartment model with 10 active ion conductances).
- Comparison of resting versus exercise-induced neuromodulatory effects.
Main Results:
- Exercise training induces dendrite restructuring, increased protein synthesis, and enhanced neuromuscular transmission in alpha-motoneurons.
- Electrophysiological changes include hyperpolarization, increased action potential rate, and larger afterhyperpolarization.
- Computational modeling suggests adaptations involve alterations in ion conductances and potentially gene expression of ion channel subunits.
- Acute neuromodulatory effects of monoamines during exercise appear opposite to resting adaptations in trained motoneurons.
Conclusions:
- Alpha-motoneuron adaptations to exercise training involve significant structural and electrophysiological modifications.
- These adaptations may be mediated by changes in ion channel function and gene expression.
- The interplay between exercise, neuromodulators, and motoneuron excitability requires further investigation.