The Effects Of Circadian Rhythm Gene Per1 On The Expression Of Related Genes In Periodontium In The Process Of Orthdontic

Part I The effects of circadian rhythm gene Per1 on the expression of osteogenesis related genes in vitro.Objective To explore the relationship of relative expression between Per1 gene and osteogenesis related gene.Method C ulturing MC3T3-E1 cells in vitro,treating them with dexamethasone, collecting these cells at 0h, 2h, 4h, 8h, 12 h, 16 h, 20 h, 24 h and then using quantitative real time PC R to quantify them.Result After using dexamethasone, the expression of Per1 reached the peak after 8h, which was nine fold of initial value. The expression of osteogenesis related gene ALP reached the peak after 8h. The expression of osteogenesis related gene OC reached the peak after 12 h, which was 20 times of initial value.Osteogenesis related gene MMP2 's expression declined sharply, which reached the valley at 4h and then increased slowly to the initial value at 12 h.Conclusion After treating MC3T3- E1 cells with dexamethasone, osteogenesis related genes' expression level, including ALP, OC and MMP2,changed with the level of PER1 gene's expression.Part II To establish an animalmodel to explore the effects of circadian rhythm gene Per1 on the expression of related genes in periodontium.Objective To establish animal model for orthodontic tooth movement and investigate the expression of Per1 in periodontal tissues during orthodontic treatment.Method After one week adapting period under 12 h light and 12 h dark, 8-week-old male Sprague Dawley(SD) rats were installed with a piece of orthodontic appliance between maxillary central incisors and maxillary right first molar. The distance of movement was measured by micro-CT during the next two weeks. Histological analysis was performed in maxillaries and Real-time quantitative PCR assays from periodontal tissues around movement teeth were performed to quantify the expression of the core circadian gene Per1 after the animals were sacrified.Result The average movement of first molar was 0.45 mm after two weeks. Alveolar bone was absorbed on the pressure side and new bone was deposited on the tension side. The expression of Per1 was oscillated with circadian rhythm. The expression of osteogenesis related gene ALP reached the peak at ZT3 and ZT15. The expression of osteogenesis related gene OC reached the peak at ZT6 and ZT18, which was ten fold of initial value. In contrast, the expression of osteogenesis related gene MMP2 slowly declined in the first 3h and then increased to the initial value at 12 h.Osteoclastogenisis gene TRAP reached the peak at ZT3 and ZT15, Osteoclastogenisis gene TRAP reached the peak at ZT18, equaled five fold of initial value.Conclusion Per1 was found and maintained the circadian rhythm in orthodontic periodontal tissue. The expression of osteogenesis related gene ALP, OC,MMP2 and osteoclastgenesis related gene TRAP,DC-STAMP changed with the expression level of Per1 gene's expression.