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The turnover of collagen is controlled by the balance between collagen synthesis and degradation;. The production of collagenase (matrix rnetalloproteinase 1). and its inhibitor, tissue inhibitor´of~matri)cnetalloproteinase-.h (TIMP-1).are´:onet´of the substances which r gulate this balance periodontal ligament fibrobIast plays an important role. in collagen metabolism during orthodontic treatlment rs believed to be an origin of the.osteoblast m the alveolar bone. The eollagenase;secreted by the periodontal ligament fibroblast and the osteoblast initiates..-the.-bone. resorptio i ´by :removing.-´the osteoid+layer in- the alveloar bone. The mterle}rkrar IR rs secreted by the macrophage? during.orthodontic- tmenk Tire :present´-study :was undertaken to assess the effect bf mechanical stress and interleukin-l R.´ on the expression of collagenase;and-T11VIP-3,in the periodontal kgamept fibroblasts,using reverse transcription polymerase chain reaction and mmunohistochemical staining The periodontal ligament frbroblasts were stretched by placing the Petriperr .dish on thelop of -spheroidal convex´ watch glass-:(5%.." surface increase) and tt ated with interleukm 1R (1.0 ng/mi), or treated´ with. both of them. Treatrnent.with:mechanical stress and/or interleukm 1 R resulted in increased collagenase mRNA expression. The mechanical stress treated group {161, 1.62, 1:37 fold increase), the mterieukin-hg`treated; group, (168 1.60 3.78 fold increase), the. mechanical stress and nterleukm-l R: treated group (1 1 2 5- fold increase) induced increases in collagenaseinENA compared -with the control group after 2 4´8 hours respectively But, ´. 1 mPNA expressions at experimental groups were decreased after Z 4° hours ´´-and increased after"8 hours." mechanical stress treated group (0.16, 0.49 fold decrease and 3.7´7 fold incease), -the-interleukin-l R.´-tia- ted`grou (015,, 044 fold: decrease_. and 446 fold increase),, the mechanical stress- and;interleukin-l P treated group (10.15, 0.69 fold decrease and 481 fold increase).induced changes in TlMP-1,nRNA compated?with-tlie c6otrvl group>after 2;=:4 8. hors,-respeetiv ly. hnmu iolustochemical stain showed that increased co lagenase and TIMP-1 staining of the mechanical stress treated group, a he mterleukrn-18 treated group and ? the mechanical stress and interleukrn ´ 1 R . Heated %=grorip` compared. :with that of at e contrail ´ group after 8;hours. These findings suggest that mechanical stress- and interleukin--8 regulate--expressions of eoliagenase and TIMP-1:
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