Nitric oxide: a spatial second messenger

Abstract

Fast synaptic transmission by excitatory neurotransmitters endows neural tissue with remarkable computational power but is limited in its ability to adapt with experience. Information in the nervous system can also be distributed beyond the synapse by biogenic amines or neuropeptides released at non-synaptic sites to elicit volume transmission and by the spatial second messenger nitric oxide which can diffuse from a synapse to a volume of surrounding neural tissue. Volume transmission and spatial signaling complement classic point-to-point transmission and may coordinate local activity among groups of neurons and glia. An interesting dialogue exists between these systems. Nitric oxide produced in response to excitation of a neuron by glutamate stimulates exocytosis and release of glutamate and dopamine from nearby neurons. Dopamine in turn can alter the strength of glutamatergic synapses and affect synaptic plasticity.