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Factors regulating condylar cartilage growth under repeated load application
A F S Ng1, Y O Yang, R W K Wong
1Orthodontics, Faculty of Dentistry, The University of Hong Kong, 2/F Prince Philip Dental Hospital, Sai Ying Pun, Hong Kong SAR, China.
Frontiers in Bioscience : a Journal and Virtual Library
|September 9, 2005
Summary
Repeated mechanical loading on the jawbone significantly increases PTHrP and SOX9 gene expression in rats. This suggests these genes promote condylar cartilage growth in response to mechanical stress.
Area of Science:
- Biomechanical Engineering
- Skeletal Biology
- Molecular Genetics
Background:
- Mechanical loading influences bone cell behavior, affecting skeletal mass and architecture.
- SOX9 and PTHrP genes are key regulators of chondrocyte differentiation and endochondral bone formation.
Purpose of the Study:
- To investigate the impact of repeated mechanical loading on gene expression in mandibular condylar cartilage.
- To determine the relationship between mechanical loading and the expression of SOX9 and PTHrP genes.
Main Methods:
- 280 Sprague-Dawley rats were divided into experimental (mechanical loading) and control groups.
- Mechanical loading was applied using a bite-jumping device.
- Real-time RT-PCR quantified PTHrP and SOX9 gene expression in mandibular condylar cartilage at 10 time points.
Main Results:
- PTHrP expression peaked on day seven and showed further increases after repeated loading.
- SOX9 expression levels were highly correlated with PTHrP expression.
- Both genes exhibited similar expression patterns following mechanical loading.
Conclusions:
- Repeated mechanical loading of the condyle stimulates PTHrP and SOX9 gene expression.
- This gene expression response is linked to the promotion of condylar cartilage growth.