The effect of running exercise on intervertebral disc extracellular matrix production in a rat model.
METHODS
Using a running rat model, the effects of physical exercise on cellular function and intervertebral disc (IVD) extracellular matrix were studied.


OBJECTIVE
To investigate whether 3-weeks treadmill running exercise can stimulate matrix production and cellular proliferation of the IVD.


BACKGROUND
Appropriate physical exercise plays an important role in the treatment of patients with low back pain-associated IVD disorder. However, it is unknown how regular exercise affects the disc at the cellular level.


METHODS
Twelve Sprague-Dawley rats underwent a daily treadmill exercise regime for a total of 3 weeks. Twelve nonexercised rats served as controls. The spinal lumbar IVD were collected and paraffin embedded for histologic analysis. Cell counts were determined on hematoxylin-eosin- and Masson-Trichrome-stained paraffin sections. Protein expression of collagen-I, collagen-II, aggrecan, Sox-9, and Sox-6 was evaluated with immunohistochemical staining. mRNA expression of Sox-9 and collagen-2 were studied by in situ hybridization. Proteoglycans were visualized with Alcian blue. Apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay.


RESULTS
The cell numbers in the anulus fibrosus (AF) increased by 25% (P < 0.05) after 3 weeks of exercise. Collagen-2 and Sox-9 mRNA were strongly expressed in the nucleus pulposus (NP) samples of the running group, but weakly expressed in the controls. An increase in collagen-II, aggrecan, and Sox-9 protein expression in NP and AF regions of the disc was detected in the exercised rats compared with controls. Quantification of Alcian blue staining demonstrated increased proteoglycan in both NP (8-fold) and AF (7-fold) in the exercised group compared with controls (P < 0.05). In addition, no significant differences were observed between the experimental groups in cellular apoptosis, collagen-I, or Sox-6 expression.


CONCLUSIONS
In this study, increased extracellular matrix production and cell proliferation with no induction of disc cell apoptosis was observed in the lumbar IVD after a 3-week running regimen in rats, suggesting that regular exercise may have an augmentative effect on cells and matrix production.
Brisby
Helena
H
Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg University, Gothenburg, Sweden.
Wei
Ai Qun
AQ
Molloy
Tim
T
Chung
Sylvia A
SA
Murrell
George A
GA
Diwan
Ashish D
AD
D053674:Aggrecans / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D049109:Cell Proliferation; D024043:Collagen Type II / Q000235:genetics; D005109:Extracellular Matrix / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D020287:In Situ Nick-End Labeling; D007403:Intervertebral Disc / Q000166:cytology / Q000378:metabolism*; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011509:Proteoglycans / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012420:Running / Q000502:physiology*; D055758:SOX9 Transcription Factor / Q000235:genetics; D013997:Time Factors
D053674:Aggrecans; D024043:Collagen Type II; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D055758:SOX9 Transcription Factor