Neuropeptide (NP)

Neuropeptides are a vast and diverse class of small signaling molecules, typically ranging from 3 to 40 amino acids, that are synthesized and released by neurons to modulate various physiological and behavioral processes. They act primarily as ligands for G protein-coupled receptors (GPCRs), where they influence critical functions such as appetite, sleep-wake cycles, pain perception, and the stress response. Unlike classical small-molecule neurotransmitters, neuropeptides often exhibit a slower onset and more prolonged duration of action, frequently functioning as neuromodulators that fine-tune the activity of neural circuits rather than mediating rapid synaptic transmission. In clinical medicine, the neuropeptide signaling systems are major targets for addressing conditions ranging from metabolic disorders and chronic pain to neurological and psychiatric ailments. However, the term "Neuropeptide" refers to a broad functional category containing hundreds of distinct molecules—such as Substance P, Oxytocin, and Neuropeptide Y—rather than a single specific protein target. Key therapeutic challenges in this space include the high susceptibility of peptides to enzymatic degradation and the difficulty of delivering large, polar molecules across the blood-brain barrier.

Other names

Neurotransmitter peptidePeptidergic signaling moleculeNeuromodulatory peptideNeuroactive peptide

Modulation of G protein-coupled receptors (GPCRs) as agonists, antagonists, or allosteric modulators; some therapeutic strategies also utilize monoclonal antibodies to sequester the neuropeptide ligands directly.