Sudo A, Miki K
Department of Industrial Physiology, National Institute of Industrial Health, Kawasaki, Japan.
Ind Health. 1995;33(2):57-66. doi: 10.2486/indhealth.33.57.
To clarify the time course of circadian rhythm adaptation to a phase shift of the light-dark (LD) cycle, urinary excretion of catecholamines was measured in rats before and after a 12-hour or 6-hour phase delay of a 12-hour light and 12-hour dark schedule. In rats under a basal condition, distinct circadian rhythms in catecholamine excretion were observed, especially in adrenaline excretion. During the 1st and 2nd days after a 12-hour phase delay, the acrophase and amplitude of adrenaline rhythm remained almost unchanged, but thereafter the acrophase was retarded and the amplitude was reduced. The acrophase once again became constant after 5 or 6 days, but the ratio of amplitude to mesor in the circadian rhythm of adrenaline excretion and the ratio of light-period to 24-hour noradrenaline excretion were readjusted to the new LD schedule on 11th or 12th day. IN the 6-hour phase delay of the LD cycle, similar findings were observed, and the results suggested adaptation on the 5-6th day. It is considered that the circadian rhythms of the sympathetic adrenomedullary function are restored, at the latest, 12 days after a 12-hour delay of the LD cycle, and 6 days after a 6-hour delay, suggesting that rats need approximately 1 day to adapt to a 1-hour phase shift.
为了阐明昼夜节律对明暗（LD）周期相位变化的适应时间进程，在12小时光照和12小时黑暗时间表延迟12小时或6小时前后，测量了大鼠尿中儿茶胺的排泄量。在基础条件下的大鼠中，观察到儿茶胺排泄存在明显的昼夜节律，尤其是肾上腺素排泄。在12小时相位延迟后的第1天和第2天，肾上腺素节律的峰相位和振幅几乎保持不变，但此后峰相位延迟，振幅减小。在5或6天后，峰相位再次变得恒定，但肾上腺素排泄昼夜节律中振幅与中值的比值以及光照期与24小时去甲肾上腺素排泄的比值在第11天或第12天重新调整到新的LD时间表。在LD周期6小时相位延迟中，观察到类似的结果，结果表明在第5 - 6天出现适应。据认为，在LD周期延迟12小时后，最晚在12天恢复交感肾上腺髓质功能的昼夜节律，在延迟6小时后6天恢复，这表明大鼠大约需要1天来适应1小时的相位变化。
