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Auditory Brainstem Response and Outer Hair Cell Whole-cell Patch Clamp Recording in Postnatal Rats
Published on: May 24, 2018
Stapedius muscle fiber characterization during postnatal development in the rat
Patrick F M Dammeijer1, Paul van Dijk, Johannes J Manni
1Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Maastricht, P.O. Box 5800, 6202 AZ Maastricht, The Netherlands. pdammeijer@home.nl
Hearing Research
|July 15, 2006
Summary
The stapedius muscle develops rapidly, with myosin heavy chain (MHC) expression changing significantly after birth. Adult MHC patterns emerge by the third postnatal week, coinciding with the start of adult-like auditory function in rats.
Area of Science:
- Muscle physiology
- Developmental biology
- Auditory neuroscience
Background:
- The stapedius muscle (SM) protects the cochlea from noise damage, requiring fast contraction and endurance.
- Auditory function in rats matures by the third postnatal week, coinciding with middle ear pneumatization.
Purpose of the Study:
- To investigate developmental changes in myosin composition within rat stapedius muscle (SM) fibers.
- To correlate myosin heavy chain (MHC) isoform expression with functional maturation of the SM.
Main Methods:
- Enzyme-histochemistry for myofibrillar adenosine triphosphatase (mATPase) activity on SM cross-sections from rats aged postnatal day (PND) 7 to 84.
- Immunohistochemistry using myosin heavy chain (MHC) antibodies to identify fiber types and MHC isoforms.
- Classification of fibers based on mATPase lability and MHC expression profiles.
Main Results:
- Embryonal (Emb) MHC was present at PND 7, decreasing by PND 14 and absent later.
- Myosin heavy chain IIB (MHC IIB) expression decreased from ~50% at PND 7-14 to 3% at PND 84.
- Postnatal day 21 marked a stabilization in mATPase-based fiber classification, with reduced expression of multiple MHC isoforms per fiber.
Conclusions:
- The stapedius muscle (SM) exhibits precocious development compared to limb muscles and diaphragm.
- The adult MHC isoform phenotype expression aligns with the onset of mature auditory function around the third postnatal week in rats.
