Effects of bite force lost on the expression of iNOS mRNA in the rat periodontium

Objective To establish iNOS for the study of molecular mechanism of the effect of bite force loss on periodontium remodeling. Methods Eighty-one male Wistar rats(weigh 250±20g)were chosed to establish rat models of different bite force for the study, and left maxillary molars of rats were extracted and left mandibular molar area was used as the model with bite force lost. The animals were sacrificed after 6 hours, 1,2,3 days and 1,2,3,4 weeks. The prepared tissue specimens were processed for the study of the change in the histologic morphology and the expression of iNOSmRNA in PDLC and osteoblasts with HE staining and RT-PCR techniques. Results In the group of lost biting force, the derangement of periodontal ligament and resorption of alveolar bone were observed in histologic study: the structure of periodontal ligament deranged .fibers and cells arrayed disorderly, there were many holes in the alveolar bone, occasionally occurred osteoclasts; the expression of iNOSmRNA was observed dramatically changed: the expression of iNOSmRNA in periodontal ligament fibroblasts and osteoblasts was higher than normal, especially at 2d and 3w. Conclusion Bite force lost induce the expression of iNOSmRNA enhanced apparently in PDLC and osteoblasts, it suggestes that iNOS may play important roles in the process of periodontium remodeling.