Prolonged upright posture induces degenerative changes in intervertebral discs of rat cervical spine.
METHODS
An in vivo study of the cervical intervertebral discs (IVDs) response to upright posture was performed using an amputated bipedal rat model.


OBJECTIVE
To investigate the effects of upright posture on IVDs of rat cervical spine.


BACKGROUND
The distinct arrangement of human neck muscle from that of cat and rhesus indicated that in the evolution process, upright posture might have affected cervical spine of human ancestors. However, the effects of upright posture on cervical spine have not been assessed.


METHODS
Forty-one-month-old rats were randomly divided into 5-month-control, 5-month-surgery, 7-month-control, and 7-month surgery group (n = 10 per group). Both forelimbs of 2 surgery group rats were amputated, and those rats were then induced to be upright in the custom-made cages. Two control group rats were kept in regular cages. These rats were respectively killed at the fifth and seventh month after surgery and the IVD samples of lumbar spine were harvested for histologic and immunohistochemical studies. Total RNA isolated from these samples were used for real-time polymerase chain reaction of type II collagen (Col2a1), type X collagen, matrix metalloproteinase 13 (MMP-13), MMP-3, aggre-can, and aggrecanase-2 (ADAMTS-5).


RESULTS
Upright posture affects histologic changes of the cervical IVDs such as fissures of anulus fibrosus and decreased height of disc, decreased protein level of Col2a1 at nucleus pulposus and anulus fibrosus, up-regulated MMP-13, MMP-3, ADAMTS-5, and type X collagen mRNA expression, and downregulated mRNA expression of Col2a1 and aggrecan.


CONCLUSIONS
Upright stance accelerates cervical disc degeneration in rats.
Liang
Qian-Qian
QQ
Department of Orthopaedics and Traumatology, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.
Cui
Xue-Jun
XJ
Xi
Zhi-Jie
ZJ
Bian
Qin
Q
Hou
Wei
W
Zhao
Yong-Jian
YJ
Shi
Qi
Q
Wang
Yong-Jun
YJ
D051722:ADAM Proteins / Q000235:genetics; D000071116:ADAMTS5 Protein; D053674:Aggrecans / Q000235:genetics; D000671:Amputation, Surgical; D000818:Animals; D002574:Cervical Vertebrae / Q000378:metabolism / Q000473:pathology*; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D024121:Collagen Type X / Q000235:genetics; D005552:Forelimb / Q000601:surgery; D007150:Immunohistochemistry; D007403:Intervertebral Disc / Q000378:metabolism / Q000473:pathology*; D055959:Intervertebral Disc Degeneration / Q000209:etiology* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D053509:Matrix Metalloproteinase 13 / Q000235:genetics; D019278:Matrix Metalloproteinase 3 / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011187:Posture; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D053674:Aggrecans; C511513:COL2A1 protein, rat; D024043:Collagen Type II; D024121:Collagen Type X; D051722:ADAM Proteins; D000071116:ADAMTS5 Protein; C518696:Adamts5 protein, rat; D053509:Matrix Metalloproteinase 13; C507083:Mmp13 protein, rat; D019278:Matrix Metalloproteinase 3