Sodium is essential for all living organisms¹. Animals including insects and mammals detect sodium primarily through peripheral taste cells^2,3,4,5,6,7. It is not known, however, whether animals can detect this essential micronutrient independently of the taste system. Here, we report that Drosophila Ir76b mutants that were unable to detect sodium² became capable of responding to sodium following a period of salt deprivation. From a screen for cells required for the deprivation-induced sodium preference, we identified a population of anterior enteric neurons, which we named internal sodium-sensing (INSO) neurons, that are essential for directing a behavioural preference for sodium. Enteric INSO neurons innervate the gut epithelia mainly through their dendritic processes and send their axonal projections along the oesophagus to the brain and to the crop duct. Through calcium imaging and CaLexA experiments, we found that INSO neurons respond immediately and specifically to sodium ions. Notably, the sodium-evoked responses were observed only after a period of sodium deprivation. Taken together, we have identified a taste-independent sodium sensor that is essential for the maintenance of sodium homeostasis.

钠对于所有生物体都是必需的¹。包括昆虫和哺乳动物在内的动物主要通过外周味觉细胞检测钠^2,3,4,5,6,7。然而，尚不清楚动物是否能够独立于味觉系统检测到这种必需的微量营养素。在这里，我们报告说，无法检测钠^2的果蝇Ir76b突变体在一段时间的缺盐后变得能够对钠做出反应。通过对剥夺引起的钠偏好所需的细胞进行筛选，我们识别出一群前肠神经元，我们将其命名为内部钠感应（INSO）神经元，它们对于指导对钠的行为偏好至关重要。肠 INSO 神经元主要通过其树突状突起支配肠道上皮，并将其轴突投射沿着食道发送到大脑和作物导管。通过钙成像和CaLexA实验，我们发现INSO神经元对钠离子立即做出特异性反应。值得注意的是，只有在缺钠一段时间后才能观察到钠诱发的反应。综上所述，我们已经确定了一种与味觉无关的钠传感器，它对于维持钠稳态至关重要。