A semiquantitative scoring tool to evaluate eccentric exercise-induced muscle damage in trained rats


Unaccustomed eccentric exercise is a well-documented cause of exercise-induced muscle damage. However, in trained subjects muscle injury involves only light or moderate tissue damage. Since trained rats are widely used as a model for skeletal muscle injury, here we propose a semiquantitative scoring tool to evaluate muscle damage in trained rats. Twenty male Sprague-Dawley rats were trained fortwo weeks following a two-week preconditioning period, and randomly divided into two groups: control rats (CTL; n=5) and rats with eccentric exercise-induced muscle damage (INJ; n=15). Injured rats were sacrificed at three time points: 1, 3 and 7 days post injury (n=5 each). Transverse sections from the right soleus were cut (10 µm) and stained with haematoxylin-eosin. Samples were evaluated by two groups of observers (four researchers experienced in skeletal muscle histopathology and four inexperienced) using the proposed tool, which consisted of six items organised in three domains: abnormal fibre morphology, necrotic/(re)degenerating fibres (muscle fibre domain), endomysial and perimysial infiltration (inflammatory state domain) and endomysium and perimysium distension (interstitial compartment domain). We observed the expected time course in the six evaluated items. Furthermore, agreement among observers was evaluated by measuring the Intraclass Correlation Coefficient (ICC). Within the experienced group, items from the muscle fibre and interstitial compartment domains showed good agreement and the two items from the infiltration compartment domain showed excellent agreement. in conclusion, the proposed tool allowed quick and correct evaluation of light to moderate muscle damage in trained rats with good agreement between observers.



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Author Biography

J.R. Torrella, University of Barcelona

Associate Professor

Departament de Fisiologia i Immunologia
Facultat de Biologia

Universitat de Barcelona

Technical Notes
Supporting Agencies
Spain’s Ministry of Economy and Competitiveness, MuscleTech Network
Histopathology, haematoxylin-eosin, histochemical method.
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How to Cite
Rizo-Roca, D., Ríos-KristjánssonJ., Núñez-EspinosaC., AscensãoA., MagalhãesJ., Torrella, J., PagèsT., & Viscor, G. (2015). A semiquantitative scoring tool to evaluate eccentric exercise-induced muscle damage in trained rats. European Journal of Histochemistry, 59(4). https://doi.org/10.4081/ejh.2015.2544