Substance that modifies, enhances or diminishes the effect of a neurotransmitter, often via second messengers operating on ion channels; can act presynaptically or postsynaptically.
A compound, released by a neuron, that adjusts the sensitivities of another neuron to specific neurotransmitters.
Compound that is released within a localized region of CNS, the receptor for which is not necessarily sited on an anatomically apposed postsynaptic cell. Thus a neuromodulator may affect several postsynaptic cells with specificity conferred mainly by the distribution of receptors. Main action is on second messenger systems, eg. cAMP or inositole triphosphate, presumably affecting protein phosphorylation, also see Neurohormone, Neurotransmitter