Identification of postprandial sodium sensor in the drosophila gut

Abstract

Sodium is one of the most important micronutrients for the maintenance and survival of living organisms. Animals primarily detect sodium through the action of peripheral taste cells, which evokes an unique salt taste. However, it is poorly unknown whether animal respond to sodium in the digestive tract that independently of taste sensing. Here we report drosophila that unable to detect or tract sodium became capable of responding to sodium after a period of dietary sodium deprivation. From a screen for cells required for the deprivation-induced sodium preference, we identify a population of anterior enteric neurons, which we named INSO (Internal Sodium Sensing) neurons, that are necessary and sufficient for inducing behavioral preference for sodium following deprivation and marked with AstC-R1. INSO enteric neurons innervate into the gut epithelia mainly through their dendritic processes and send their axonal projection to the brain and crop duct. INSO enteric neurons respond immediately and specifically to sodium ion. We found the ligand AstC has putative role that mediate NaCl preference by modulating AstC-R1+ enteric neurons and AstC was expressed in posterior midgut enterocytes response to sodium ingestion. Together, this study identifies a previously unknown taste-independent sodium sensor that is essential for the maintenance of sodium homeostasis.