Cervical disc degeneration induced by bilateral facetectomy in rats

English Keywords:【Key words】 Disc degeneration  Cartilage endplate  Facetectomy  Lesion  Rats

English Abstract:

  【Abstract】 Objectives: To investigate an animal model of intervertebral disc degeneration induced by bilateral facetectomy. Methods: Sixteen Sprague-Dawley female rats with the age of 3 months were assigned evenly and randomly into experimental and control group. The C4/5 and C5/6 bilateral facet joints were sectioned by using a burr in the experimental group. The C4-C6 spinal samples were harvested at 12 weeks after surgery. The C5/6 segments were scanned by using micro-CT and stained with Safranine O/fast green. The intervertebral disc height(IDH), the microstructure of C5 vertebral body, ratio of cartilage endplate lesion(CEL) area to the whole endplate area and disc degeneration score were calculated. The mRNA expression of aggrecan, type Ⅱ collagen(Col2α1), matrix metalloprotease(MMP)-3 and MMP-13 in C4/5 disc were analyzed by using real-time PCR. The statistical significance between groups was determined by using the independent t test with significant difference level at P<0.05. Results: The IDH following facetectomy was significantly lower than that in the control(0.51±0.04mm vs 0.55±0.02mm), and the CEL was greater than that in the control(11.5±2% vs 6.9±1%). The CEL appeared on the ventral side of the inferior endplate, and defect area was noted at peripheral and central of upper endplate. There was a significant increase of BV/TV and Th.Sp following facetectomy. Histological results showed the cartilage endplate lesions and few calcification. The disorganized annular fibers, shrinked nucleus pulposus and less cells in the nucleus pulposus were observed in the discs following facetectomy. The disc degeneration score was 8.6±0.8 and 5.8±0.5 in the experimental group and control group, respectively, and the difference between 2 groups was significant. There was a significantly down-regulated expression of aggrecan and col2α1 while significantly up-regulated expression of MMP-13. Conclusions: Bilateral facetectomy will lead to the disc degeneration of cervical spine not only in morphology, but also in histology and molecular biology, which is a reliable rat model for disc degeneration.