Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA.
Institute for Anatomy, University Hospital, Duisburg-Essen University, Essen, Germany.
Nat Neurosci. 2017 Jul;20(7):927-933. doi: 10.1038/nn.4575. Epub 2017 May 29.
Initiation of drinking behavior relies on both internal state and peripheral water detection. While central neural circuits regulating thirst have been well studied, it is still unclear how mammals recognize external water. Here we show that acid-sensing taste receptor cells (TRCs) that were previously suggested as the sour taste sensors also mediate taste responses to water. Genetic silencing of these TRCs abolished water-evoked responses in taste nerves. Optogenetic self-stimulation of acid-sensing TRCs in thirsty animals induced robust drinking responses toward light even without water. This behavior was only observed when animals were water-deprived but not under food- or salt-depleted conditions, indicating that the hedonic value of water-evoked responses is highly internal-state dependent. Conversely, thirsty animals lacking functional acid-sensing TRCs showed compromised discrimination between water and nonaqueous fluids. Taken together, this study revealed a function of mammalian acid-sensing TRCs that provide a cue for external water.
饮水行为的启动依赖于内部状态和外周水检测。虽然中枢神经回路调节口渴已有很好的研究，但哺乳动物如何识别外部水仍然不清楚。在这里，我们表明，先前被认为是酸味传感器的酸感应味觉受体细胞（TRC）也介导对水的味觉反应。这些 TRC 的基因沉默消除了味觉神经对水诱发的反应。在口渴的动物中，光遗传自刺激酸感应 TRC 会诱导对光的强烈饮水反应，即使没有水也是如此。这种行为仅在动物缺水而不是在食物或盐缺乏的情况下观察到，表明水诱发反应的愉悦值高度依赖于内部状态。相反，缺乏功能性酸感应 TRC 的口渴动物在水和非水流体之间的辨别能力受损。总之，这项研究揭示了哺乳动物酸感应 TRC 的一个功能，为外部水提供了一个线索。
