A study on the generation of circadian rhythm in hard tissue metabolism

本研究旨在探讨这一现象的发生机制。硬组织新陈代谢的昼夜节律。实验是用大鼠进行的。得到了以下结果。(1)骨形成和骨吸收的血清标志物随昼夜节律波动，在动物静息期达到高峰，在活动期达到最低点。(2)骨吸收阻滞剂(依替膦酸盐和利塞膦酸盐)可降低骨吸收标志物水平，但不影响骨形成标志物的昼夜节律。然而，下降的幅度在一天中并不是一致的，在动物的休息时间段最大。(3)血清中的某些体液因子(S)可能在破骨细胞性骨选择昼夜节律的产生中起重要作用。(4)RT-PCR分析显示Clock基因在硬组织细胞(破骨细胞、成骨细胞、成牙本质细胞和成釉细胞)中有昼夜节律性表达。上述结果提示硬组织代谢的昼夜节律在设计未来的实验、治疗方案以及解释实验或临床数据中的重要性。

The present study was undertaken to investigate the mechanism on the generation. of circadian rhythms in hard tissue metabolism. Experiments were carried out using rats. The following results were obtained. (1)Serum markers of both bone formation and resorption fluctuated according to circadian rhythms, with peaks during the animals rest span, and nadirs during the animals' active span. (2)The administration of blockers of bone resorption (etidronate and risedronate) decreased the level of bone-resorption markers without affection the circadian patterns of bone formation markers. However, the magnitude of the decrease was not uniform throughout the day, and was greatest during the animals' rest span. (3)Some humoral factor(s) in serum might play an important role in generating the circadian rhythm of osteoclastic bone resopt ion. (4) RT-PCR analyses revealed circadian expression of clock genes in hard tissue cells (osteoclasts,osteoblasts,odontoblasts and ameloblasts). The above results suggest the importance of circadian rhythms of hard tissue metabolism in the design of future experiment, treatment regimen, and in the interpretation of experimental or clinical data.