日本熊本大学一个研究小组在《自然—神经科学》杂志网络版上发表报告说，实验发现在果蝇的脑内，睡眠和记忆这两种行为，是被完全独立的两个神经回路所控制。
据研究人员介绍，神经传递物质多巴胺在睡眠和记忆过程中发挥重要作用，但这种物质的作用机制一直以来都是个谜。
在实验中，研究人员首先通过基因操作，在果蝇脑内称为扇形体的部位形成多巴胺受体。结果，多巴胺发挥作用后，果蝇的睡眠时间减少，也就是说，扇形体是果蝇的睡眠中枢；在另一组实验中，研究人员在果蝇脑内已知与记忆有关的蘑菇体内制作相同受体，果蝇的睡眠却没有发生变化。这表明，果蝇的睡眠和记忆是分别由各自独立的神经回路所控制。
此外，实验结果还显示，果蝇脑内的扇形体和蘑菇体会分别与其他神经细胞释放的多巴胺发生反应。
领导这项研究的熊本大学副教授粂和彦说，这一新发现有助研究人员找到新途径，向睡眠中的脑部输入信息，未来将有可能实现在睡眠中学习。（生物谷Bioon.com）
doi:10.1038/nn.3238
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Identification of a dopamine pathway that regulates sleep and arousal in Drosophila
Taro Ueno, Jun Tomita, Hiromu Tanimoto, Keita Endo, Kei Ito, Shoen Kume, & Kazuhiko Kume
Sleep is required to maintain physiological functions, including memory, and is regulated by monoamines across species. Enhancement of dopamine signals by a mutation in the dopamine transporter (DAT) decreases sleep, but the underlying dopamine circuit responsible for this remains unknown. We found that the D1 dopamine receptor (DA1) in the dorsal fan-shaped body (dFSB) mediates the arousal effect of dopamine in Drosophila. The short sleep phenotype of the DAT mutant was completely rescued by an additional mutation in the DA1 (also known as DopR) gene, but expression of wild-type DA1 in the dFSB restored the short sleep phenotype. We found anatomical and physiological connections between dopamine neurons and the dFSB neuron. Finally, we used mosaic analysis with a repressive marker and found that a single dopamine neuron projecting to the FSB activated arousal. These results suggest that a local dopamine pathway regulates sleep.
