Chatterjee Abhishek, Hardin Paul E
Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX, USA.
Fly (Austin). 2010 Oct-Dec;4(4):283-7. doi: 10.4161/fly.4.4.13010. Epub 2010 Oct 9.
Circadian clocks keep time in the digestive, circulatory, reproductive, excretory and nervous systems even in absence of external cues. Central oscillators in the brain control locomotor activity of organisms ranging from fruit flies to man, but the functions of the clocks in peripheral nervous system are not well understood. The presence of autonomous peripheral oscillators in the major taste organ of Drosophila, the proboscis, prompted us to test whether gustatory responses are under control of the circadian clock. We find that synchronous rhythms in physiological and behavioral responses to attractive and aversive tastants are driven by oscillators in gustatory receptor neurons (GRNs); primary sensory neurons that carry taste information from the proboscis to the brain. During the middle of the night, high levels of G protein-coupled receptor kinase 2 (GPRK2) in the GRNs suppresses tastant-evoked responses. Flies with disrupted gustatory clocks are hyperphagic and hyperactive, recapitulating behaviors typically seen under the stress of starvation. Temporal plasticity in innate behaviors should offer adaptive advantages to flies. In this Extra View article we discuss how oscillators inside GRNs regulate responsiveness to tastants and influence feeding, metabolism and general activity.
即使在没有外部线索的情况下，生物钟仍能在消化系统、循环系统、生殖系统、排泄系统和神经系统中保持时间节律。大脑中的中央振荡器控制着从果蝇到人类等生物体的运动活动，但生物钟在周围神经系统中的功能尚未得到充分了解。果蝇主要味觉器官喙中存在自主的外周振荡器，这促使我们测试味觉反应是否受生物钟的控制。我们发现，味觉受体神经元（GRNs）中的振荡器驱动着对吸引性和厌恶性味觉物质的生理和行为反应的同步节律；GRNs是将味觉信息从喙传递到大脑的初级感觉神经元。在午夜时分，GRNs中高水平的G蛋白偶联受体激酶2（GPRK2）会抑制味觉物质诱发的反应。味觉生物钟被破坏的果蝇会出现食欲亢进和活动过度的现象，重现了通常在饥饿压力下出现的行为。先天行为的时间可塑性应该会为果蝇带来适应性优势。在这篇“额外观点”文章中，我们讨论了GRNs中的振荡器如何调节对味觉物质的反应性，并影响进食、新陈代谢和一般活动。
