Neuropeptide Y

What is Neuropeptide Y?

Neuropeptide Y (NPY) is a 36-amino-acid peptide and the most abundant neuropeptide in the mammalian central nervous system. It was isolated by Tatemoto and Mutt in 1982 from porcine brain. The "Y" reflects both its founder's classification system and the prominence of tyrosine residues at both N- and C-termini.

NPY is research-only and not approved for any therapeutic use. Intranasal NPY is in clinical investigation at Mount Sinai (Yehuda lab) and elsewhere for post-traumatic stress disorder (PTSD), where its strong endogenous anxiolytic and stress-resilience properties are pharmacologically attractive.

Structure and Family

NPY belongs to the pancreatic polypeptide family along with:

• Pancreatic polypeptide (PP) — gut hormone, released after meals
• Peptide YY (PYY) — gut hormone, satiety signal
• Neuropeptide Y (NPY) — central nervous system, multiple functions

All three are 36-37 amino acids and adopt a common "PP-fold" structure (a hairpin that brings N- and C-termini close together).

Mechanism and Functions

NPY signals through five Y receptor subtypes (Y1, Y2, Y4, Y5, Y6 — Y6 is non-functional in humans), each with distinct distributions and functions:

Feeding behavior:

• Y1 receptor — central NPY release in arcuate nucleus is the most potent endogenous orexigenic signal
• Y5 receptor — also drives feeding behavior

Anxiety and stress resilience:

• Y1 receptor in amygdala mediates strong endogenous anxiolytic effect
• NPY is among the most powerful endogenous anxiolytics known
• Higher endogenous NPY correlates with greater stress resilience in humans

Other functions:

• Circadian rhythm modulation (suprachiasmatic nucleus)
• Memory and learning
• Cardiovascular regulation (sympathetic co-transmitter)
• Bone homeostasis
• Reproduction (interaction with kisspeptin)

Therapeutic Investigation — Intranasal NPY for PTSD

A growing body of research has investigated intranasal NPY as a treatment for PTSD:

• Phase 1 (Biological Psychiatry 2018) — single-dose intranasal NPY in healthy volunteers and PTSD patients showed dose-dependent reductions in anxiety symptoms
• Phase 2 studies are ongoing at Mount Sinai
• The intranasal route bypasses the blood-brain barrier (NPY does not cross BBB after systemic administration) and delivers peptide directly to olfactory and trigeminal neural pathways

The therapeutic hypothesis is that boosting endogenous anxiolytic NPY signaling in stress-related circuits can dampen the hyperresponsive amygdala signaling that underlies PTSD symptoms, including hyperarousal, intrusive memories, and avoidance.

Research Applications

NPY is used in research for:

• Anxiety and stress models — i.c.v. or intranasal NPY administration in rodents
• Feeding behavior studies — orexigenic challenge in metabolic research
• Sympathetic nervous system biology — co-transmitter studies with norepinephrine
• Y receptor characterization — pharmacology of subtype-selective agonists and antagonists
• PTSD translational research

Distinction from PYY

NPY and PYY (peptide YY 3-36) are closely related (38% sequence identity) but functionally distinct:

The same neuropeptide family, opposite metabolic effects.

Place in Research

NPY remains one of the most-studied neuropeptides in physiology, with sustained interest in three areas: stress and PTSD therapeutics, obesity pathophysiology, and basic neuroscience of motivation and emotion. It is sold by research chemical suppliers and used widely in academic and pharmaceutical research.