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Neuropeptide Y
A 36-amino acid neuropeptide that is one of the most abundant peptides in the central nervous system, involved in appetite regulation, stress responses, anxiety, and cardiovascular function.
Overview
Neuropeptide Y (NPY) is a 36-amino acid peptide discovered in 1982 by Kazuhiko Tatemoto and Viktor Mutt from porcine brain extracts. Named for the tyrosine (Y) residues at both its amino and carboxyl termini, NPY is one of the most abundant and widely distributed neuropeptides in the mammalian brain. It belongs to the pancreatic polypeptide family alongside peptide YY (PYY) and pancreatic polypeptide (PP).
NPY acts through a family of at least five G-protein coupled receptor subtypes (Y1, Y2, Y4, Y5, and Y6). Its most well-characterized role is as a potent stimulator of food intake. NPY is abundantly expressed in the arcuate nucleus of the hypothalamus, where it acts as a key orexigenic (appetite-stimulating) signal. Central administration of NPY in animal models produces dramatic increases in food intake, and elevated hypothalamic NPY levels are observed during fasting. The Y1 and Y5 receptors are primarily responsible for mediating NPY's feeding effects.
Beyond appetite regulation, NPY plays critical roles in stress resilience and anxiety. High levels of NPY have been associated with stress resilience in both animal models and human studies, including research on soldiers exposed to extreme military training. Conversely, low NPY levels correlate with increased vulnerability to stress-related disorders including post-traumatic stress disorder (PTSD). This has led to interest in NPY or Y receptor agonists as potential treatments for anxiety and PTSD.
NPY also has important cardiovascular effects, causing vasoconstriction and potentiating the effects of norepinephrine. In the sympathetic nervous system, NPY is co-released with norepinephrine from sympathetic nerve terminals during stress and exercise, contributing to blood pressure regulation. Additional functions include roles in circadian rhythm regulation, bone formation, and immune modulation, reflecting the extraordinary diversity of this neuropeptide's biological roles.