| Tendinosis-like histologic and molecular changes of the Achilles tendon to repetitive stress: a pilot study in rats. | |
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MedLine Citation:
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PMID: 21800208 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: Tendinopathy (pain and tendon degeneration) is associated with repetitive use and mechanical overload. However, the etiology of tendinopathy remains unclear. Clarification of histologic and molecular changes of tendon to repetitive stress could provide better understanding of Achilles tendon disorders related to repetitive stress. QUESTIONS/PURPOSES: We asked whether repetitive stress simulating overuse of the Achilles tendon induced (1) histologic changes in rats similar to tendinosis (increased cellularity of fibrocytes, increased disorganization of collagen fiber, and increased roundness of the nucleus of the fibrocyte), (2) increased collagen Type III occurrence, and (3) increased inducible nitric oxide synthase (iNOS) expression. METHODS: We used an exercise protocol simulating repetitive, jerky, eccentric contraction of the triceps surae in 15 rats. We conducted the exercise for 2 hours per day, three times per week using the right rear legs only and the left legs as internal controls. We harvested Achilles tendons after either 2, 4, or 6 weeks of exercise, and evaluated changes in tendon thickness, fibrocyte count, collagen fiber arrangement, collagen fiber type, and occurrence of iNOS. RESULTS: Exercised Achilles tendons showed increased cellularity of fibrocytes at 4 and 6 weeks of exercise, and disorganized collagen fiber arrangement at 6 weeks of exercise. There was a trend for Type III collagen occurrence being greater in experimental groups. Expression of iNOS increased after 2 and 4 weeks of exercise when compared with that of the controls, but decreased after 6 weeks. CONCLUSIONS: These observations suggest repetitive, synchronized, passive, and jerky exercise induced by electrical stimulation can lead to the tendinosis-like changes in the Achilles tendons in rats with imbalance between synthesis and degeneration after 4 weeks of exercise. CLINICAL RELEVANCE: This newly designed exercise protocol may be used to design an animal model of Achilles tendon overuse. With this model, therapeutic interventions of tendinopathy could be analyzed by investigation of tendon biology and response in terms of histologic and molecular changes. |
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Authors:
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Nam Soon Cho; Ji Hye Hwang; Yong Taek Lee; Seoung Wan Chae |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2011-07-29 |
Journal Detail:
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Title: Clinical orthopaedics and related research Volume: 469 ISSN: 1528-1132 ISO Abbreviation: Clin. Orthop. Relat. Res. Publication Date: 2011 Nov |
Date Detail:
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Created Date: 2011-09-30 Completed Date: 2011-11-30 Revised Date: 2011-12-21 |
Medline Journal Info:
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Nlm Unique ID: 0075674 Medline TA: Clin Orthop Relat Res Country: United States |
Other Details:
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Languages: eng Pagination: 3172-80 Citation Subset: AIM; IM |
Affiliation:
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Department of Physical Medicine and Rehabilitation, Korea University Ansan Hospital, Korea University College of Medicine, Gyeonggi-do, Korea. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Achilles Tendon
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metabolism,
pathology* Animals Biological Markers / metabolism Cell Nucleus / pathology Collagen Type III / metabolism Cumulative Trauma Disorders / metabolism, pathology* Disease Models, Animal Electric Stimulation Fibroblasts / metabolism, pathology Male Muscle Contraction Nitric Oxide Synthase Type II / biosynthesis Physical Conditioning, Animal Pilot Projects Rats Rats, Sprague-Dawley Stress, Mechanical Tendinopathy / metabolism, pathology* |
| Chemical | |
Reg. No./Substance:
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0/Biological Markers; 0/Collagen Type III; EC 1.14.13.39/Nitric Oxide Synthase Type II; EC 1.14.13.39/Nos2 protein, rat |
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