Joseph F, Chan B Y, Durham B H, Ahmad A M, Vinjamuri S, Gallagher J A, Vora J P, Fraser W D
Department of Diabetes and Endocrinology, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, United Kingdom.
J Clin Endocrinol Metab. 2007 Aug;92(8):3230-8. doi: 10.1210/jc.2006-1832. Epub 2007 Jun 5.
Osteoclast resorptive activity, which is known to demonstrate circadian rhythmicity, is regulated by various endocrine hormones and cytokines. PTH suppresses osteoprotegerin (OPG), a regulator of osteoclast activity that has recently been shown to have a circadian rhythm in healthy controls. We studied the differences in the relationship between PTH, OPG, and type I collagen C-telopeptide (betaCTX) over a 24-h period in premenopausal women, elderly postmenopausal women, and elderly men.
Hourly peripheral venous blood samples were obtained from 18 healthy non-osteoporotic volunteers: premenopausal women (n = 6; mean age, 30.2 +/- 2.2 yr), postmenopausal women (n = 6; mean age, 68.2 +/- 2.6 yr), and elderly men (n = 6; mean age, 68.2 +/- 2.3 yr). Plasma PTH (1-84), OPG, betaCTX, and calcium were measured on all samples. Cosinor analysis was performed to analyze the circadian rhythm parameters. Cross-correlation analysis was used to determine the relationship between the time series of the variables.
The 24-h mean PTH, OPG, and betaCTX concentrations were significantly higher in postmenopausal women as compared with premenopausal women and elderly men (P < 0.001). Significant circadian rhythms were observed for PTH (P < 0.05), OPG (P < 0.05), and betaCTX (P < 0.001) in all subjects. PTH secretion was characterized by two peaks in premenopausal women and elderly men and by a sustained increase in PTH concentration in postmenopausal women. OPG secretion was circadian with a daytime increase and nocturnal decrease, and a greater percent decrease in OPG secretion was observed in the postmenopausal women between 1600 and 2400 h. OPG secretion was inversely related to PTH (r = -0.4) and betaCTX (r = -0.6) secretion over a 24-h period.
This report confirms a circadian rhythm for circulating OPG. The nocturnal decline in circulating OPG is greater in postmenopausal women as compared with premenopausal women and elderly men. Altered PTH secretion may contribute to the OPG secretory pattern in postmenopausal women resulting in increased nocturnal bone resorption.
破骨细胞的吸收活性已知具有昼夜节律性，受多种内分泌激素和细胞因子调节。甲状旁腺激素（PTH）可抑制骨保护素（OPG），后者是一种破骨细胞活性调节因子，最近研究表明其在健康对照者中也有昼夜节律。我们研究了绝经前女性、老年绝经后女性和老年男性在24小时内PTH、OPG和I型胶原C末端肽（βCTX）之间关系的差异。
从18名健康非骨质疏松志愿者获取每小时外周静脉血样本：绝经前女性（n = 6；平均年龄，30.2±2.2岁）、绝经后女性（n = 6；平均年龄，68.2±2.6岁）和老年男性（n = 6；平均年龄，68.2±2.3岁）。对所有样本检测血浆PTH（1 - 84）、OPG、βCTX和钙。进行余弦分析以分析昼夜节律参数。采用交叉相关分析确定变量时间序列之间的关系。
绝经后女性的24小时平均PTH、OPG和βCTX浓度显著高于绝经前女性和老年男性（P < 0.001）。所有受试者的PTH（P < 0.05）、OPG（P < 0.05）和βCTX（P < 0.001）均观察到显著的昼夜节律。绝经前女性和老年男性的PTH分泌有两个峰值，绝经后女性的PTH浓度持续升高。OPG分泌具有昼夜节律，白天升高夜间降低，绝经后女性在1600至2400时OPG分泌的下降百分比更大。在24小时内，OPG分泌与PTH（r = -0.4）和βCTX（r = -0.6）分泌呈负相关。
本报告证实循环OPG存在昼夜节律。与绝经前女性和老年男性相比，绝经后女性循环OPG的夜间下降幅度更大。绝经后女性PTH分泌的改变可能导致OPG分泌模式改变，从而导致夜间骨吸收增加。
