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

本研究旨在探讨其产生的机制。硬组织代谢的昼夜节律。实验用大鼠进行。得到了以下结果：(1)骨形成和骨吸收的血清指标均随昼夜节律波动，在动物休息时段达到峰值，在动物活动时段达到最低点。(2)骨吸收阻滞剂（依地膦酸酯和利塞膦酸酯）的使用降低了骨吸收标志物的水平，但不影响骨形成标志物的昼夜节律模式。然而，这种下降的幅度在一天中并不均匀，在动物休息期间最大。(3)血清中某些体液因子可能在破骨细胞骨吸收的昼夜节律产生中起重要作用。(4) RT-PCR分析揭示了硬组织细胞（破骨细胞、成骨细胞、成牙细胞和成釉细胞）中时钟基因的昼夜节律表达。上述结果提示硬组织代谢的昼夜节律在未来实验设计、治疗方案以及实验或临床数据解释中的重要性。

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.