Wee B E, Turek F W
Department of Psychology, Tulane University, New Orleans, LA 70118.
Brain Res. 1989 Dec 29;505(2):209-14. doi: 10.1016/0006-8993(89)91444-3.
The effects of light on the circadian system may involve the neurotransmitter acetylcholine (ACh). The purpose of the present study was to determine whether carbachol, a cholinergic agonist, mimics the phase-shifting effects of light on the circadian rhythm of locomotor activity (CRLA) in the Djungarian hamster. Phase response curves (PRCs) were measured for blind animals injected intracerebroventricularly with either vehicle or carbachol at different circadian times. Carbachol produced significant phase delays in the CRLA when administered at circadian time (CT) 12-16 and small, but significant phase advances when given at CT 8. No consistent phase shifts were observed in response to carbachol injections at other circadian times. Phase shifts produced by carbachol injections at CT 8 and 12 were similar for both sighted and blind animals. Light pulses to sighted hamsters produced phase advances at CT 20 and phase delays at CT 12. Both the carbachol PRC and the PRC for light pulses in the Djungarian hamster have phase delay regions in the early subjective night. However, these two PRCs have different phase advance regions. These results indicate that carbachol mimics some of the effects of light on the circadian system in the Djungarian hamster and support the hypothesis that cholinergic mechanisms may play a role in mediating some of the phase-shifting effects of light on the circadian clock of mammals.
光对昼夜节律系统的影响可能涉及神经递质乙酰胆碱（ACh）。本研究的目的是确定胆碱能激动剂卡巴胆碱是否能模拟光对黑线毛足鼠运动活动昼夜节律（CRLA）的相位转移作用。在不同的昼夜时间，对经脑室内注射赋形剂或卡巴胆碱的失明动物测量相位反应曲线（PRCs）。当在昼夜时间（CT）12 - 16给予卡巴胆碱时，它会使CRLA产生显著的相位延迟，而在CT 8给予时则产生小但显著的相位提前。在其他昼夜时间注射卡巴胆碱时，未观察到一致的相位变化。在CT 8和12注射卡巴胆碱产生的相位变化，对于有视力和失明的动物来说是相似的。对有视力的仓鼠给予光脉冲，在CT 20时产生相位提前，在CT 12时产生相位延迟。黑线毛足鼠中卡巴胆碱的PRC和光脉冲的PRC在主观夜早期都有相位延迟区域。然而，这两个PRC有不同的相位提前区域。这些结果表明，卡巴胆碱模拟了光对黑线毛足鼠昼夜节律系统的一些影响，并支持了胆碱能机制可能在介导光对哺乳动物昼夜节律时钟的一些相位转移作用中发挥作用的假说。
