Circadian rhythms in the hard tissue metabolism and their relations to the effect of blockers of bone resorption and formation

在本研究中，研究了骨吸收和形成阻滞剂对大鼠骨形成和吸收的昼夜节律性时间结构的意义和性质。在生理条件下，骨形成和骨吸收都遵循昼夜节律，在光明期（动物休息期）达到高峰，在黑暗期（动物活动期）达到最低点。骨吸收阻滞剂（降钙素和双膦酸盐）和形成（大剂量地替膦酸盐）的作用强度也随给药时间或药物效果观察时间的不同而每天变化，这表明靶部位（骨吸收或形成过程）对药物的敏感性也每天变化。此外，大鼠牙齿运动和牙周组织对正畸力和下颌骨对正畸力的反应随施加正畸力的时间而变化。上述发现应被证明是重要的，不仅在未来的实验设计和数据的解释，而且在有效使用药物或有效的医疗或牙科治疗影响骨吸收和骨形成。

In the present study, the significance and the nature of the circadian-rhythmic temporal structure of bone formation and resorption, were investigated in rats in relation to the effect of blockers of bone resorption and formation. Under physiological conditions, both bone formation and resorption followed circadian rhythms with a peak during the light period (resting period of the animal) and with a nadir during the dark period (active period of the animal). The magnitude of the effects of blockers of bone resorption (calcitonin and bisphosphonates) and formation (a large dose of etidronate) also varied diurnally depending on the time of drug administration or the time of observation of the drug effect, which indicatess that the susceptibility of the target site (the process of bone resorption or formation) to the drugs also varied diurnally. Furthermore, tooth movement and changes in periodontal tissue response to orthodontic force and response of mandible to orthopedic force in rats varied depending on the time of day the force was applied. The above findings should prove to be important, not only in future experimental design and interpretation of the data, but also in the efficacious use of drugs or efficacious medical or dental treatments which affect bone resorption and bone formation.