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 (GABAA, glycine) and excitatory (glutamate, cholinergic) synaptic receptors as well as functional GABAB and muscarinic receptors, but not glutamatergic metabotropic ones, to modulate Ca2+ 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.