| BackgroundIdipoathci Socliossi (IS) is a kind of vertebral malformation which usally occurs in children and adolescence, and it is still unkown about the cause of it. Some possible etiological factors had been arised in resent researchs, such as genetic factors, growth factors, the affect of hormone, the lesion of connective tissue, abnormality of muscle system, the factors of nervous system, effect of melatonin and platelets factors, but up to now the recognition of the causes of IS is on the very beginning stage both in our country or abroad. So it is difficult to prevent or cure this disease on the etiological stage.The animal IS model is an important tool to reseach the etiology and pathogenesis of IS, scoliosis had been induced by certain factors in the previous animal models, this had offered important evidence to discuss etiology and proved hypothesis in different ways, for example:wedge-ectomy of vertebrae, blocking of endplate, fixation of consecutive bodies, articular process ectomy, rib ectomy, cutting of paravertebral muscle, cutting of intercostal nerves and posterior root of spinal cord and some others. As these models were made into scoliosis by destroy the paravertebral tissue mostly, it is difficult to imitate the changes in IS in etiological side. Many reseaches were about asymmetry linkage models in all the scoliosis models, such as making linkage between scapula and contralateral pelvis to induce scoliosis by Kallemeier, and Sarwark had obtained the constant structral scoliosis by making linkage between scapula and homolateral pelvis. These animal models were induced on the basis of normal vertebral anatomic structure, so these could imitate the physiological characteristics of IS well, are better than the other types of animal models.IS is a kind of disease related with growth, the scoliosis may be worse only if patients have growing potency. The most direct factors which are related with vertebral growth are the development of intervertebral disc and endplate cartilage. There was merely reseach concered on the effect of intervertebral disc and endplate cartilage during the period of scoliosis happen and development, and it was also difficult to get these tissue from the IS patients.In this reseach, we hope we can obtain a new type of IS animal model (two-feet-rat model) by making linkage between scapula and homolateral and contralateral pelvis, then compare its Cobb angle and vertebral rotation angle with the two-feet-rat model which was made by making linkage between scapula and homolateral, to find the adventage of this new type model. And then we observed the intervertebral disc and endplate cartilage from these models by ways of histology, immunohistochemisty and flow cytometer to dicuss the reasons and mechanism in scoliosis happen and development, and to make experimental foundation for the futher etiological reseaches of IS.ObjectiveTo find the adventage of the new-style two-feet-rat model by compare the Cobb angle and vertebral rotation angle between the models which were made by making linkage between scapula and homolateral and contralateral pelvis and the models which was made by making linkage between scapula and homolateral pelvis. To reseach the apoptosis of intervertebral disc cells of the new-style models and the effect of expression of Fas in scoliosis happen and development.MethodThirty Westa rats with nearly ablactation were distributed into 4 groups by random. Five rats were included in the control group with no disposal; five (two-feet-rat group) were made into two-feet-rats by cutting off the pair of upper extremities and tail; 10 (bilateral linkage group) were made into two-feet-rats and then were made linkage between the scapula and the homolateral and contralateral pelvis; the other 10 rats (unilateral linkage group) were made into two-feet-rats and then were made linkage between the scapula and the homolateral pelvis. Check the vertebral changes of these rats after 3 months, observe the apoptosis of intervertebral cells by flow cytometer (PI), observe the expression of Fas in endplate by the way of immunohistochemisty.ResultThere was no scoliosis happened in control group or two-feet-rat group; scoliosis were occurred in all the 10 rats of bilateral linkage group, the Cobb angles were 57 to 97 degree (76.5 degree by mean), the rotation angles of top vertebrae were 0 to 17 degree (11.2 degree by mean); all the rats of unilateral linkage group were also obtained to be scoliosis, the Cobb angles were 18 to 62 degree (42.1 degree by mean), the rotation angles of top vertebrae were 0 to 8 degree (4.3 degree by mean). In all the models which were made into scoliosis, the relation betweent the Cobb angle and the rotation angle of top vertebrae was analysised statistically, the results (r=0.558, P<0.05) showed that there was statitstical relationship between them. We found that wedging change was existed in the intervertebral discs of Westa rats with scoliosis during reseaching on the top vertebrae of scoliosis spines. Compare with the control group, two-feet-rat group and the protruded side of scoliosis spine, more cell apoptosis could be observed in the discs of faveolus side; expression of Fas were enchaced in the cells of faveolus side intervertebral discs.Conclusion1. The new-style two-feet-rat (bilateral linkage group) are better than the rats of unilateral linkage group in terms of coronary curve (Cobb angle) and axial rotation (rotation angle of top vertebrae). The morphological, histological and biomechanic characteristics of two-feet-rats are likely to the human beings, and these scoliosis were happened by the linkage and the gravity without broken of paravertebral structure, have well imitated the characteristics of IS.2. There are relationship between the the Cobb angle and the rotation angle of top vertebrae.3. The cells growth of intervertebral discs of Westa rats can be inhibitated by two-feet status.4. Apparente apoptosis are existed at the faveolus side of top vertebral body in these scoliosis models.5. Expression of Fas is increased in the endplate at the faveolus side of top vertebral body, the apoptosis of cells in the endplate at the faveolus side may be regulated by Fas.6. The biomechanical factor is the reason of cell apoptosis in these models during the scoliosis happen and development, and the apoptosis of intervertebral disc cells and endplate cells will make the scoliosis worse, this is an infernal circle.
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