Endogenous signaling molecules secreted by neurons that alter the behavior of neurons or effector cells. Neurotransmitter is used here in its most general sense, including not only messengers that act directly to regulate ion channels, but also those that act through second messenger systems, and those that act at a distance from their site of release. Included are neuromodulators, neuroregulators, neuromediators, neurohormones, and neurohumors, whether or not acting at synapses.

Substances secreted by neurons into the blood, CNS, or intercellular space.

Substances used for their pharmacological actions on any aspect of neurotransmitter systems. Neurotransmitter agents include agonists, antagonists, degradation inhibitors, uptake inhibitors, depleters, precursors, and modulators of receptor function.

Synonyms: Neurohumor, Neurotransmitter Agent, Neuromodulators, Substance, Nerve Transmitter, Nerve Transmitter Substance, Substances, Nerve Transmitter, Neuroregulators, Neurohumors, 0, Transmitter Substance, Nerve, Neurotransmitter Agents, Neurotransmitters, Neuromodulator, Nerve Transmitter Substances, Neurohormones, Neurotransmitter, Transmitter Substances, Nerve, Neurohormone, Neuroregulator