Neurochemical

Neurochemical refers to a chemical substance that participates in signaling within the nervous system. In neuroscience, the term encompasses neurotransmitters, neuromodulators, and neurohormones, all of which influence neuronal activity by interacting with specific receptors. Neurochemistry studies how these chemicals are produced, released, transported, and cleared, and how their signaling shapes brain function and behavior.

Neurotransmitters are released from presynaptic terminals to convey rapid signals across synapses. Classic examples include acetylcholine, dopamine, norepinephrine, serotonin, glutamate, and GABA. Neuromodulators, including neuropeptides and endocannabinoids, can alter the probability or strength of synaptic transmission and often act on receptors that influence intracellular signaling cascades over longer timescales. Neurohormones are released by neurosecretory cells into the bloodstream to act at distant targets, with vasopressin and oxytocin being notable examples.

Neurochemical signaling underlies most brain functions, including mood, arousal, movement, learning and memory, perception, and autonomic regulation. Signaling involves receptor binding, second messenger systems, modulation of ion channels, and changes in gene expression and synaptic plasticity. The system is regulated by mechanisms such as reuptake, enzymatic degradation, and diffusion away from the synapse.

Dysregulation of neurochemical signaling is linked to numerous disorders. Alterations in serotonin, norepinephrine, and dopamine systems are associated with mood disorders and psychosis, while imbalances in GABA and glutamate are implicated in anxiety and epilepsy. Treatments often target specific neurochemical systems, using antidepressants, antipsychotics, cholinergic agents, or agents that modulate GABA or glutamate signaling to restore balance.

Researchers use methods such as microdialysis, voltammetry, immunoassays, and neuroimaging to measure neurochemical levels and receptor activity, advancing understanding of brain function and the basis of neurological and psychiatric diseases.