Hastings M H, Mead S M, Vindlacheruvu R R, Ebling F J, Maywood E S, Grosse J
Department of Anatomy, University of Cambridge, UK.
Brain Res. 1992 Sep 18;591(1):20-6. doi: 10.1016/0006-8993(92)90973-d.
This study investigated the relative potency of melatonin and arousal as Zeitgebers in the non-photic phase shifting of circadian rhythmicity in the adult Syrian hamster. Animals held under dim red light (DD) exhibited robust free-running rhythms of wheel-running activity. Melatonin (1 mg/kg) or ethanolic saline vehicle, delivered manually by subcutaneous injection after removing the animal from its cage, resulted in phase advances of the activity rhythm. This effect was phase dependent, injections at CT 8 and 10 being effective (CT 12 = anticipated activity onset), whereas injection at CT 2, 6, 14 and 20 did not cause a shift. There was no significant difference between the magnitude or timing of phase shifts in response to injections of saline or melatonin. To determine whether the observed shifts were related to arousal of the animals induced by handling, a second group held under DD were fitted with chronic s.c. cannulae so that melatonin solution or vehicle could be delivered remotely at projected CT 10. Neither solution had any effect upon the free-running rhythm. However, when these animals received manual s.c. injection of saline or melatonin solution, they exhibited phase advances similar to those observed in Expt. 1. These results fail to support the hypothesis that melatonin can exert a chemically specific, acute phase-shifting action in the adult Syrian hamster. They do, however, demonstrate the potent effect of arousing stimuli upon the circadian clock in this species.
本研究调查了褪黑素和唤醒作为授时因子在成年叙利亚仓鼠昼夜节律非光相移中的相对效力。饲养在昏暗红光（DD）条件下的动物表现出稳健的自由运转的轮转活动节律。在将动物从笼中取出后，通过皮下注射手动给予褪黑素（1毫克/千克）或乙醇生理盐水载体，导致活动节律出现相位提前。这种效应是相位依赖性的，在CT 8和10进行注射有效（CT 12 =预期活动开始时间），而在CT 2、6、14和20进行注射则不会引起节律变化。注射生理盐水或褪黑素后，相位变化的幅度或时间没有显著差异。为了确定观察到的节律变化是否与处理引起的动物唤醒有关，将另一组饲养在DD条件下的动物安装慢性皮下插管，以便在预计的CT 10远程给予褪黑素溶液或载体。两种溶液对自由运转节律均无任何影响。然而，当这些动物接受手动皮下注射生理盐水或褪黑素溶液时，它们表现出与实验1中观察到的类似的相位提前。这些结果不支持褪黑素能在成年叙利亚仓鼠中发挥化学特异性急性相位变化作用的假设。然而，它们确实证明了唤醒刺激对该物种昼夜节律钟的强大影响。
