5月5日，《神经科学杂志》（The Journal of Neuroscience）发表了中国科学院上海生命科学研究院神经科学研究所神经环路与动物行为研究组最新研究成果。该项工作由博士研究生陈子敬及工作人员王清秀在王佐仁研究员的指导下共同完成。
在果蝇中，水可以作为一种独特的味觉感受。水通过降低渗透压的机制来激活味觉刚毛（taste sensilla）中特定的味觉神经元。但是，关于什么分子可作为渗透压感受器来参与果蝇的味觉水感受，尚不清楚。通过药理学实验，陈子敬等发现上皮钠通道的阻断剂amiloride及其类似物能够特异地拮抗味觉神经元（gustatory receptor neurons）对水刺激的电生理反应，并抑制果蝇对水的味觉行为。敲除果蝇上皮钠通道家族其中一个成员ppk28基因，可以使得味觉神经元对水的电生理反应几乎完全消失，并降低果蝇对水的味觉行为反应。将PPK28通道异位表达在中间型味觉刚毛（intermediate-type taste sensilla）的苦味细胞中，可以使中间型味觉刚毛获得应答水刺激的能力。这些研究结果提示PPK28通道作为渗透压感受器，参与果蝇的味觉水感受。
PPK28介导果蝇味觉水感受（图片来源：ＳＩＢＳ）
该工作得到了中国科学院、科技部与国家自然科学基金等项目的资助。
推荐原文出处：
The Journal of Neuroscience doi:10.1523/JNEUROSCI.0627-10.2010
The Amiloride-Sensitive Epithelial Na+ Channel PPK28 Is Essential for Drosophila Gustatory Water Reception
Zijing Chen,1,2 Qingxiu Wang,1 and Zuoren Wang1
1 Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences and
2 Graduate School, Chinese Academy of Sciences, Shanghai 200031, China
Water sensation is a specific taste modality in the fruit fly. Water-induced hypoosmolarity activates specific gustatory receptor neurons; however, the molecular identity of the putative osmolarity sensor in these neurons remains unknown. We found that amiloride and its analogs specifically antagonized the response of water gustatory receptor neurons and the behavior of flies toward water stimulation. Deletion of the gene that encodes the amiloride-sensitive PPK28 channel, a DEG/eNaC (degenerin/epithelial sodium channel) family member, abolished the water-induced activity of water gustatory receptor neurons and greatly diminished the behavioral response of flies to water. Ectopic expression of the PPK28 channel in the bitter cells within the intermediate-type sensilla renders these sensilla responsive to water stimuli. Thus, the amiloride-sensitive PPK28 channel may serve as the osmolarity sensor for gustatory water reception in the fruit fly.
