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Muscle Nerve. 2016 Jan;53(1):118-26. doi: 10.1002/mus.24702. Epub 2015 Nov 23.

Intermittent stretching induces fibrosis in denervated rat muscle.

Author information

1
Research Laboratory of Neurological Physiotherapy, Department of Physiotherapy, Federal University of São Carlos, São Carlos, São Paulo, Brazil.
2
Laboratory of Muscle Plasticity, Department of Physiotherapy, Federal University of São Carlos, São Carlos, São Paulo, Brazil.

Abstract

INTRODUCTION:

Stretching (St) has been used for treating denervated muscles. However, its effectiveness and safety claims require further study.

METHODS:

Rats were divided into: (1) those with denervated (D) muscles, evaluated 7 or 15 days after sciatic nerve crush injury; (2) those with D muscles submitted to St during 7 or 15 days; and (3) those with normal muscles. Muscle fiber cross-sectional area, serial sarcomere number, sarcomere length, and connective tissue density were measured. MMP-2, MMP-9, TIMP-1, TGF-β1, and myostatin mRNAs were determined by real-time polymerase chain reaction. MMP-2 and MMP-9 activity was evaluated by zymography. Collagen I was localized using immunofluorescence.

RESULTS:

St did not prevent muscle atrophy due to denervation, but it increased fibrosis and collagen I deposition at day 15. St also upregulated MMP-9 and TGF-β1 gene expressions at day 7, and myostatin at day 15.

CONCLUSIONS:

Stretching denervated muscle does not prevent atrophy, but it increases fibrosis via temporal modulation of TGF-β1/myostatin and MMP-9 cascades.

KEYWORDS:

muscle atrophy; neurorehabilitation; physiotherapy; skeletal muscle; stretching

PMID:
25960249
DOI:
10.1002/mus.24702
[Indexed for MEDLINE]

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