A study on the role of nitric oxide in the response of periodontal tissue to mechanical stimuli

Nitric oxide, a mediator of vascular function, neurotransmission， and immune系统已经开始在机械上的自适应反应中扮演一个重要角色stress/strain. Periodontal tissue receives and adapts to various mechanical stimuli such asmasticatory force and orthodontic force. Thus，这是不可能的一个mediator of adaptive physiological response of periodontal tissue tothese mechanical stimuli. In the present study，我们测试了这一可能性both in vitro and in vivo.1)影响cyclic tension force on NO andprostaglandin E - D22 - D2 production and mRNA expression of their synthases in human periodontalligament cells. application of cyclic tension force to人类periodontal ligament cells induced arapid and transient increase in NO release in the culture medium. Endothelial isoform of NO synthase（NOS） mRNA表达式定义。Release of prostaglandin E - D22 - D2 time-dependently increased bythe application of force. Cyclooxygenase-2 mRNA表达式increasedwhereas cyclooxygenase-1 mRNA expression did not change.这些反应suggest that NO andPGE D22 D2 are involved in the adaptive response of periodontal ligament cells to mechanicalstress/strain.2) Effect of topical administration of inhibitors of NO synthase and spontaneous NOdonors on orthodontic tooth movement in rates . upper first molars of male 8-week-old Wistar rats weremoved buccally for 21 days. The topical administration of L-NAME (10mg /mL)，a general inhibitor of NOS activitycaused a significant reduction of tooth movement. On the other hand, L-NIO (5mg /mL)，选择inhibitor of inducible isoform of NOS，had no effect on tooth movement There was a tendency toward a decrease in tooth movement in animalstreated with NO donors (NOR4 and NOC). These results suggest that NO sythesized by constitutiveisoforms of NOS has an important role in orthodontic tooth movement。

Nitric oxide, a mediator of vascular function, neurotransmission, and immune system, has been recently shown to play an important role in adaptive response of bone to mechanical stress/strain. Periodontal tissue receives and adapts to various mechanical stimuli such as masticatory force and orthodontic force. Thus, it is possible that NO is a mediator of adaptive physiological response of periodontal tissue to these mechanical stimuli. In the present study, we tested this possibility both in vitro and in vivo.1) Effect of cyclic tension force on NO and prostaglandin EィイD22ィエD2 production and mRNA expression of their synthases in human periodontal ligament cells.Application of cyclic tension force to human periodontal ligament cells induced a rapid and transient increase in NO release in the culture medium. Endothelial isoform of NO synthase (NOS) mRNA expression decreased. Release of prostaglandin EィイD22ィエD2 time-dependently increased by the application of force. Cyclooxygenase-2 mRNA expression increased, whereas cyclooxygenase-1 mRNA expression did not change. These results suggest that NO and PGEィイD22ィエD2 are involved in the adaptive response of periodontal ligament cells to mechanical stress/strain.2) Effect of topical administration of inhibitors of NO synthase and spontaneous NO donors on orthodontic tooth movement in rats.Upper first molars of male 8-week-old Wistar rats were moved buccally for 21 days. The topical administration of L-NAME (10 mg/mL), a general inhibitor of NOS activity, caused a significant reduction of tooth movement. On the other hand, L-NIO (5 mg/mL), a selective inhibitor of inducible isoform of NOS, had no effect on tooth movement. There was a tendency toward a decrease in tooth movement in animals treated with NO donors (NOR4 and NOC). These results suggest that NO sythesized by constitutive isoforms of NOS has an important role in orthodontic tooth movement.