人们总是认为，吃得越多越容易发胖，事实上可能并非如此。美国科学家近日研究发现，增加进食并不一定会导致脂肪的增长。这一发现为找到控制体重的新药靶开启了可能性。相关论文发表在6月4日的《细胞—代谢》（Cell Metabolism）杂志上。
美国加州大学旧金山分校的Kaveh Ashrafi等人以秀丽隐杆线虫（Caenorhabditis elegans）为实验材料，利用RNA干扰技术研究了250多种基因，以分析神经递质serotonin对进食和脂肪的影响机制。
结果发现，serotonin对食欲和脂肪堆积的控制是通过两个独立的信号通路来实现的。一组信号调控进食，另一组独立信号调控脂肪代谢。这些信号路径由一连串分子事件组成，由脑部神经元触发，并最终“指示”机体燃烧或贮存脂肪。
Ashrafi表示，如果这种独立通道的机制也存在于人体中，那么就可以开发新的减肥药作用于脂肪堆积通道，而不是作用于饥饿抑制路径（此方法目前收效甚微）。
他说：“这并不是说进食不重要，但是serotonin对脂肪的控制与进食是截然不同的。仅仅聚焦于进食的减肥策略已经走到头了，这也许就是节食失败的原因之一。”
研究人员总结说：“肥胖与苗条并不仅仅由进食行为决定。更确切地说，进食行为和脂肪代谢是神经系统感知营养获取时并列而又独立的反应。（科学网 梅进/编译）
生物谷推荐原始出处：
Cell Metabolism, Vol 7, 533-544, 04 June 2008
Article
Serotonin Regulates C. elegans Fat and Feeding through Independent Molecular Mechanisms
Supriya Srinivasan,1 Leila Sadegh,1 Ida C. Elle,2 Anne G.L. Christensen,2 Nils J. Faergeman,2 and Kaveh Ashrafi1,
1 Department of Physiology and UCSF Diabetes Center, University of California, San Francisco, San Francisco, CA 94158-2517, USA
2 Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
Corresponding author
Kaveh Ashrafi
kaveh.ashrafi@ucsf.edu
Summary
We investigated serotonin signaling in C. elegans as a paradigm for neural regulation of energy balance and found that serotonergic regulation of fat is molecularly distinct from feeding regulation. Serotonergic feeding regulation is mediated by receptors whose functions are not required for fat regulation. Serotonergic fat regulation is dependent on a neurally expressed channel and a G protein-coupled receptor that initiate signaling cascades that ultimately promote lipid breakdown at peripheral sites of fat storage. In turn, intermediates of lipid metabolism generated in the periphery modulate feeding behavior. These findings suggest that, as in mammals, C. elegans feeding behavior is regulated by extrinsic and intrinsic cues. Moreover, obesity and thinness are not solely determined by feeding behavior. Rather, feeding behavior and fat metabolism are coordinated but independent responses of the nervous system to the perception of nutrient availability.
