Neurotransmission is the electrical impulse-triggered propagation of signals between neurons or between neurons and other cell types such as skeletal muscle cells. Recent studies point out the involvement of exosomes, a type of small bilipid layer-enclosed extracellular vesicles, in regulating neurotransmission. Through horizontally transferring proteins, lipids, and nucleic acids, exosomes can modulate synaptic activities rapidly by controlling neurotransmitter release or progressively by regulating neural plasticity including synapse formation, neurite growth & removal, and axon guidance & elongation. Researchers from the Tongji University School of Medicine discuss the similarities and differences between exosomes and synaptic vesicles in their biogenesis, contents, and release. The researchers also highlight the recent progress made in demonstrating the biological roles of exosome in regulating neurotransmission, and propose a modified model of neurotransmission, in which exosomes act as novel neurotransmitters. Lastly, they provide a comprehensive discussion of the enlightenment of the current knowledge on neurotransmission to the future directions of exosome research.
The involvement of exosomes in mediating neurotransmission
As a key cellular communicator, exosomes can be secreted from both neurons and glia including astrocytes, oligodendrocytes, and microglia. Except commonly express molecules, exosomes derived from each cell types contain specific contents which can modify neurotransmission rapidly through enhancing/inhibiting presynaptic & postsynaptic signaling or progressively through regulating neurite elongation/removal, synapse formation, stress tolerance.