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Laterally projecting cerebrospinal fluid‐contacting cells in the lamprey spinal cord are of two distinct types
Author(s) -
Jalalvand Elham,
Robertson Brita,
Wallén Peter,
Hill Russell H.,
Grillner Sten
Publication year - 2014
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.23542
Subject(s) - biology , neuroscience , spinal cord , postsynaptic potential , inhibitory postsynaptic potential , excitatory postsynaptic potential , anatomy , ependymal cell , cell type , gabaergic , colocalization , microbiology and biotechnology , receptor , cell , biochemistry , genetics
Cerebrospinal fluid‐contacting (CSF‐c) cells are found in all vertebrates, but their function remains elusive. In the lamprey spinal cord, they surround the central canal and some have processes passing the gray matter to the lateral edge of the flattened spinal cord. Stimulation of CSF‐c cells at the central canal elicits GABAergic inhibitory postsynaptic potentials (IPSPs) in intraspinal stretch receptor neurons (edge cells). Here, we characterize laterally projecting CSF‐c cells according to their morphology, phenotype, and neuronal properties by using immunohistochemistry, retrograde tracing, calcium imaging, and whole‐cell recordings. We identify two types of CSF‐c cells. Type 1 cells have a bulb‐like ending that protrudes into the central canal and a lateral process that ramifies ventrolaterally and laterally with a dense plexus surrounding the mechanosensitive dendrites of the edge cells. Most type 1 cells fire spontaneous action potentials that are abolished by tetrodotoxin, and all display spontaneous excitatory postsynaptic potentials and IPSPs that remain in the presence of tetrodotoxin. GABA and somatostatin are colocalized in type 1 cells, and they express both GABA and glutamate receptors. Type 2 cells, on the other hand, have a flat ending protruding into the central canal and a laterally projecting process that ramifies only at the lateral edge. These cells show immunoreactivity to taurine, but they do not express GABA or somatostatin, nor do they have any active neuronal properties. Type 2 cells might be a form of glia. Type 1 CSF‐c cells are neurons and may play a modulatory role by influencing edge cells and thus the locomotor‐related sensory feedback. J. Comp. Neurol. 522:1753–1768, 2014. © 2014 Wiley Periodicals, Inc.