Minor influence of lifelong voluntary exercise on composition, structure, and incidence of osteoarthritis in tibial articular cartilage of mice compared with major effects caused by growth, maturation, and aging

Tommi Närhi, Ulrika Siitonen, Lauri J. Lehto, Mika M. Hyttinen, Jari P A Arokoski, Pieter A. Brama, Jukka S. Jurvelin, Heikki J. Helminen, Petro Julkunen

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4 Scopus citations

Abstract

We investigated the effects of lifelong voluntary exercise on articular cartilage of mice. At the age of 4 weeks C57BL mice (n = 152) were divided into two groups, with one group serving as a sedentary control whereas the other was allowed free access to a running wheel from the age of 1 month onward. Mice were euthanized at four different time points (1, 2, 6, and 18 months of age). Articular cartilage samples were gathered from the load-bearing area of the tibial medial plateaus, and osteoarthritis was graded. Additionally, the proteoglycan content distribution was assessed using digital densitometry, collagen fibril orientation, and parallelism with polarized light microscopy, and collagen content using Fourier transform infrared imaging spectroscopy. The incidence of osteoarthritis increased with aging, but exercise had no effect on this trend. Furthermore, the structure and composition revealed significant growth, maturation, and age-dependent properties. Exercise exerted a minor effect on collagen fibril orientation in the superficial zone. Fibril orientation at 2 months of age was more perpendicular to surface (p < 0.05) in controls compared with runners, whereas the situation was reversed at the age of 18 months (p < 0.05). The collagen content of the superficial zone was higher (p < 0.01) at the age of 18 months in controls compared with runners but the proteoglycan content did not display any exercise-dependent changes. In conclusion, growth, maturation, and aging exerted a clear effect on integrity, structure, and composition of medial tibial plateau articular cartilage in mice, whereas lifelong voluntary exercise had only a minor effect on collagen architecture and content.

Original languageEnglish (US)
Pages (from-to)380-392
Number of pages13
JournalConnective Tissue Research
Volume52
Issue number5
DOIs
StatePublished - Oct 2011

Bibliographical note

Funding Information:
Funding from the Ministry of Education, Finland, to University of Eastern Finland (project 5765) and the Academy of Finland (projects 110595 and 113112) is acknowledged.

Keywords

  • aging
  • articular cartilage
  • collagen
  • mice
  • osteoarthritis
  • physical exercise
  • proteoglycan

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