Potdar Sheetal, Sheeba Vasu
Behavioural Neurogenetics Laboratory, Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India.
J Neurogenet. 2013 Jun;27(1-2):23-42. doi: 10.3109/01677063.2013.791692. Epub 2013 May 23.
Sleep is a highly conserved behavior whose role is as yet unknown, although it is widely acknowledged as being important. Here we provide an overview of many vital questions regarding this behavior, that have been addressed in recent years using the genetically tractable model organism Drosophila melanogaster in several laboratories around the world. Rest in D. melanogaster has been compared to mammalian sleep and its homeostatic and circadian regulation have been shown to be controlled by intricate neuronal circuitry involving circadian clock neurons, mushroom bodies, and pars intercerebralis, although their exact roles are not entirely clear. We draw attention to the yet unanswered questions and contradictions regarding the nature of the interactions between the brain regions implicated in the control of sleep. Dopamine, octopamine, γ-aminobutyric acid (GABA), and serotonin are the chief neurotransmitters identified as functioning in different limbs of this circuit, either promoting arousal or sleep by modulating membrane excitability of underlying neurons. Some studies have suggested that certain brain areas may contribute towards both sleep and arousal depending on activation of specific subsets of neurons. Signaling pathways implicated in the sleep circuit include cyclic adenosine monophosphate (cAMP) and epidermal growth factor receptor-extracellular signal-regulated kinase (EGFR-ERK) signaling pathways that operate on different neural substrates. Thus, this field of research appears to be on the cusp of many new and exciting findings that may eventually help in understanding how this complex physiological phenomenon is modulated by various neuronal circuits in the brain. Finally, some efforts to approach the "Holy Grail" of why we sleep have been summarized.
睡眠是一种高度保守的行为，其作用尚不清楚，尽管人们普遍认为它很重要。在这里，我们概述了关于这种行为的许多重要问题，近年来世界各地的几个实验室使用基因易处理的模式生物黑腹果蝇对这些问题进行了研究。黑腹果蝇的休息状态已与哺乳动物的睡眠进行了比较，其稳态和昼夜节律调节已被证明受复杂的神经回路控制，该回路涉及昼夜节律时钟神经元、蘑菇体和脑间部，尽管它们的确切作用尚不完全清楚。我们提请注意关于参与睡眠控制的脑区之间相互作用的性质仍未得到解答的问题和矛盾之处。多巴胺、章鱼胺、γ-氨基丁酸（GABA）和血清素是确定在该回路不同分支中起作用的主要神经递质，它们通过调节基础神经元的膜兴奋性来促进觉醒或睡眠。一些研究表明，某些脑区可能根据特定神经元亚群的激活对睡眠和觉醒都有贡献。与睡眠回路相关的信号通路包括在不同神经底物上起作用的环磷酸腺苷（cAMP）和表皮生长因子受体 - 细胞外信号调节激酶（EGFR - ERK）信号通路。因此，这个研究领域似乎正处于许多新的、令人兴奋的发现的边缘，这些发现最终可能有助于理解这种复杂的生理现象是如何被大脑中的各种神经回路调节的。最后，总结了一些为探寻我们为何睡眠这一“圣杯”所做的努力。
