neuropeptide

Neuropeptides are a diverse class of signaling molecules formed by short chains of amino acids that neurons use to communicate. They act as neurotransmitters, neuromodulators, or neurohormones, influencing neural circuits across the central and peripheral nervous systems. Unlike many small-molecule neurotransmitters, neuropeptides are typically synthesized as larger precursor proteins (prepropeptides) in the soma, and after enzymatic processing they are packed into dense-core vesicles for transport to axon terminals. Release usually requires higher-frequency activity and can occur alongside classic neurotransmitters.

Their actions are mediated mainly by G protein-coupled receptors, though some peptides interact with other receptor types. Effects are slower to onset and longer-lasting than those of classical transmitters, modulating excitability, synaptic strength, and network dynamics. They regulate pain, appetite, stress responses, mood, memory, and social behavior, among other processes, and function in both the brain and peripheral tissues.

Representative examples include substance P, enkephalins and endorphins, neuropeptide Y, oxytocin, vasopressin, somatostatin, and calcitonin gene-related peptide (CGRP).

Dysregulation of neuropeptide signaling has been linked to migraine, chronic pain, obesity, anxiety, and depression. Therapeutic approaches include peptide analogs, receptor antagonists, and non-peptide mimetics.