Effects of aging and exercise training on the histological and mechanical properties of articular...

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Biogerontology (2012) 13:369–381 DOI 10.1007/s10522-012-9381-8

RESEARCH ARTICLE

Effects of aging and exercise training on the histological and mechanical properties of articular structures in knee joints of male rat Hideki Moriyama • Naohiko Kanemura • Inge Brouns • Isabel Pintelon • Dirk Adriaensen • Jean-Pierre Timmermans • Junya Ozawa • Nobuhiro Kito • Toshiaki Gomi • Masataka Deie

Received: 13 December 2011 / Accepted: 12 April 2012 / Published online: 22 April 2012 Ó Springer Science+Business Media B.V. 2012

Abstract The impact of aging on joints can have a profound effect on an individual’s functioning. Our objectives were to assess the histological and mechanical properties of the knee joint capsule and articular cartilage with aging, and to examine the effects of exercise on age-related changes in the knee joint. 2-year-old Wistar rats were divided into a sedentary control group and an exercise-trained group. 10-weekold animals were used to investigate the changes with

Hideki Moriyama and Naohiko Kanemura contributed equally to this work. H. Moriyama (&) M. Deie Graduate School of Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan e-mail: morihide@harbor.kobe-u.ac.jp Present Address: H. Moriyama Graduate School of Health Sciences, Kobe University, Tomogaoka 7-10-2, Suma-ku, Kobe 654-0142, Japan N. Kanemura T. Gomi School of Health and Social Services, Saitama Prefectural University, Saitama 343-8540, Japan I. Brouns I. Pintelon D. Adriaensen J.-P. Timmermans Laboratory of Cell Biology and Histology, University of Antwerp, 2020 Antwerp, Belgium J. Ozawa N. Kito Department of Physical Therapy, Hiroshima International University, Hiroshima 739-2695, Japan

aging. The joint capsule and cartilage were evaluated with histological, histomorphometric, immunohistochemical, and mechanical analyses. Severe degenerative changes in articular cartilage were observed with aging, whereas exercise apparently did not have a significant effect. The articular cartilage of aged rats was characterized by damage to the cartilage surface, cell clustering, and an abnormal cartilage matrix. Histomorphometric analysis further revealed changes in cartilage thickness as well as a decreased number of chondrocytes. Aging led to stiffness of the articular cartilage and reduced the ability to dissipate the load and distribute the strain generated within the joint. Joint stiffness with aging was independent of capsular stiffness and synovitis was not a characteristic feature of the aging joint. This study confirms that aging alone eventually leads to joint degeneration in a rat model. The lack of recovery in aging joint changes may be due to several factors, such as the duration of the intervention and the regeneration ability of the cartilage. Keywords Aging Joint capsule Cartilage Exercise Rat

Introduction Aging joint and muscle changes can have a tremendous impact on an individual’s overall functioning (Ahmed et al. 2005). Although the morphological, metabolic, and contractile properties of aging muscle

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Effects of aging and exercise training on the histological and mechanical properties of articular... by Centro de Estudos da Dor e do Movimento - Issuu