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A Rapid Automated Protocol for Muscle Fiber Population Analysis in Rat Muscle Cross Sections Using Myosin Heavy Chain Immunohistochemistry
Published on: March 28, 2017
Changes in acetylcholine receptor function induce shifts in muscle fiber type composition
Tae-Eun Jin1, Anton Wernig, Veit Witzemann
1Abt Zellphysiologie, Max-Planck-Institut für Medizinische Forschung, Heidelberg, Germany.
The FEBS Journal
|April 4, 2008
Summary
Mice lacking acetylcholine receptor (AChR) epsilon-subunits show a shift from fast to slow muscle fibers. This highlights how receptor changes influence skeletal muscle contractile properties and synaptic function.
Area of Science:
- Muscle physiology
- Neurobiology
- Molecular biology
Background:
- Mice lacking acetylcholine receptor (AChR) epsilon-subunits fail to express adult-type receptors.
- This leads to the expression of fetal-type receptors throughout postnatal life, altering postsynaptic signal transduction.
Purpose of the Study:
- To investigate the impact of altered AChR expression on skeletal muscle fiber type transition and synaptic gene expression.
- To explore the plasticity of muscle in response to changes in endplate receptor function.
Main Methods:
- Utilized AChRepsilon(-/-) mice lacking epsilon-subunits of the acetylcholine receptor.
- Analyzed changes in muscle fiber type proportions (type 1, 2A, 2B/2D) and gene/protein expression levels (troponin I(slow), AChR alpha-subunits, utrophin, MuSK).
Main Results:
- A significant increase in type 1 slow fibers (6%) and reduction in fast fibers (10-12%) observed in both soleus and extensor digitorum longus muscles.
- Increased expression of 'synaptogenic' genes, including AChR alpha-subunits and utrophin.
- Muscle-specific differences in the expression of the synaptic regulator MuSK were noted.
Conclusions:
- Altered endplate receptor function induces a fast-to-slow fiber type transition, demonstrating a novel aspect of muscle plasticity.
- Skeletal muscle acts as a self-matching system, adjusting contractile properties and synaptic function to meet functional demands.
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