Spinal cerebrospinal fluid contacting neurons are a conserved sensory neuronal population along the mouse spinal cord

Cerebrospinal Fluid contacting neurons (CSF-cNs) are present in all vertebrates around the medullo-spinal central canal. They are GABAergic, selectively express PKD2L1, a member of the TRP channel superfamily, and are thought to represent a novel sensory system intrinsic to the central nervous system. Using histology, we found that CSF-cNs form a homogeneous population, distributed along the whole spinal cord and mainly located in the ventral region of the central canal. Patch-clamp recordings reveal conserved intrinsic properties and voltage-dependent conductance expression. Spinal CSF-cNs express PKD2L1 channels and ASICs, acting as sensory receptors for extracellular pH changes. They express both inhibitory (GABA A , glycine) and excitatory (glutamate, cholinergic) synaptic receptors as well as functional GABA B and muscarinic receptors, but not glutamatergic metabotropic ones, to modulate Ca 2+ channels. CSF-cNs represent a functionally homogeneous population that might integrates sensory signals along the central canal to modulate body functions by regulating local spinal networks. Demonstrating such a function represents the future challenge in the field.