Despite the interdependence of neurons and glia, little is known about the pathways used for communication between these two cell types. Information is transferred from one neuron to the next at synapses, specialized junctions where electrical signals trigger the release of chemical neurotransmitters onto the postsynaptic neuron.
Current dogma holds that synapses are used exclusively for communication between neurons.
Recent work in Craig Jahr's laboratory, in collaboration with the laboratory of Peter Somogyi at Oxford, indicates that a revision of this conceptual framework is necessary, as they found evidence of synapses between neurons and glial cells in the hippocampus. The speed of the responses indicated that they could only be produced by the nerve endings releasing glutamate directly opposite the receptors, a process that is essentially indistinguishable from transmission that occurs at synapses between neurons. Electron micrographs prepared from these slices revealed that nerve terminals were in direct contact with OPC processes. These synapses provide a pathway linking neuronal activity to internal calcium levels in the immature glial cells. Because oligodendrocyte precursor cells are found in the adult brain, selective inhibition of this pathway may help stimulate re-myelination after injury or in diseases such as multiple sclerosis.