Sasaki T, Yamasaki M, Okumura M
Department of Bioregulation, Kumamoto University Medical School, Japan.
Prog Clin Biol Res. 1990;341B:305-15.
In the circumpolar region, the light-dark environment, which is the most potent Zeitgeber among others, and to which polar route travelers are exposed, varies greatly with the season and the time of day. Hence, resynchronization following an eastbound flight through this region will not necessarily be attained by phase advance of the biological rhythms. To prove this by simulation, a computer program was produced so as to locate the sun at any moment on any day and at any point on the earth. Rats were exposed to the changing pattern of light-dark condition which simulated flight schedules of polar, great circle and southern routes. Observation was made on the progress of biological resynchronization to the local time. The polar route simulation with an advance of 15 hours followed by a delay of the same hours resulted in phase delays on both trips. The great circle route simulation with a shift of 9 hours back and forth gave the same results. Another polar route simulation with an advance of 18 hours also resulted in a delay, while on their way back home some showed delay and some did advance. These findings suggest that the light-dark pattern after arrival works more rather than that during the trip, and that the resynchronization is apt to be achieved by delaying rather than by advancing, particularly when advancing of the phase by 6 hours or more is required. The critical limit seems to be subject to difference in species.
在极地地区，明暗环境是众多最强大的授时因子之一，极地航线旅行者会暴露于这种环境中，它随季节和一天中的时间变化很大。因此，向东飞越该地区后的重新同步化不一定能通过生物节律的相位提前来实现。为了通过模拟来证明这一点，编写了一个计算机程序，以便在任何一天的任何时刻以及地球上的任何地点定位太阳。让大鼠暴露于模拟极地、大圆和南线航班时刻表的明暗条件变化模式下。观察生物节律重新同步到当地时间的进展情况。提前15小时然后再延迟相同时间的极地航线模拟在往返行程中都导致了相位延迟。来回偏移9小时的大圆航线模拟也得到了相同的结果。另一次提前18小时的极地航线模拟也导致了延迟，而在它们返程时，一些显示出延迟，一些则出现了提前。这些发现表明，到达后的明暗模式比飞行途中的作用更大，并且重新同步化倾向于通过延迟而不是提前来实现，特别是当需要相位提前6小时或更多时。临界限度似乎因物种而异。
