Diverse paths for chemoreception in ciliated neurons contacting the cerebrospinal fluid in the spinal cord

Cerebrospinal fluid-contacting neurons (CSF-cNs) are mechanosensory cells in the spinal cord that detect compression and regulate locomotion, posture, and morphogenesis. Although CSF-cNs respond to changes in pH, neurotransmitters and metabolites, their chemosensory repertoire is not fully understood. Using hybridization chain reaction, we investigated the distribution of expression of chemoreceptors in CSF-cNs and neighboring cells in the spinal cord. We found that CSF-cNs express receptors for glutamate ( grm2 ), somatostatin ( sstr2 ) and low-density lipoprotein (LDL) (ldlrad2), indicating roles in detecting glutamate, somatostatin and LDL in the CSF. High LDL receptor expression in CSF-contacting cells suggests CSF lipid capture. Most receptors were enriched but not exclusive to CSF-cNs and also appeared in ependymal radial glial cells. Our findings indicate multiple chemosensory pathways can sustain long-distance communication between neurons and glia through the cerebrospinal fluid.