RPB

Neuropeptide Y

NPY; part of the NPY/PYY/pancreatic polypeptide family; receptors Y1, Y2, Y4, Y5 (and Y6 in some species)

Cognitive & neuro
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1What it is

Neuropeptide Y is your own peptide, isolated in 1982 from pig brain, and it is everywhere: hypothalamus, amygdala, hippocampus, brainstem, and along every sympathetic nerve, where it is stored and released alongside noradrenaline.

It does three big things. First, appetite: inject it into the hypothalamus of a sated animal and the animal eats voraciously — it is the most potent orexigenic signal known, and the NPY/AgRP neurons of the arcuate nucleus are the hunger arm of the circuit that leptin and GLP-1 drugs act on. Second, blood vessels: released with noradrenaline, it constricts vessels and sustains the constriction after the noradrenaline has gone. Third — and this is the one that generates the most interest — stress resilience. People and animals with more NPY signalling tolerate stress better, and some of the most striking human data come from studies of soldiers under extreme training stress.

It is an endogenous signalling peptide and a drug target, not a consumer compound. Community use: essentially none documented; delivery to the brain is the barrier, which is exactly why the human psychiatric work used the intranasal route.

2How it's thought to work

Y1 receptor. mediates the appetite-stimulating effect in the hypothalamus, anxiolytic effects in the amygdala, and vasoconstriction in the periphery.
Y2 receptor. presynaptic autoreceptor — reduces further NPY and neurotransmitter release. The endogenous Y2-selective fragment PYY 3-36 suppresses appetite, which is why the family contains both the strongest hunger signal and a satiety signal.
Y5 receptor. contributes to feeding, especially sustained intake.
DPP-4 cleavage. converts full-length NPY (Y1-active) into NPY 3-36 (Y2-active), effectively switching the signal — a neat regulatory mechanism and a reason DPP-4 inhibitors have been studied for off-target NPY effects.
Stress system. NPY opposes CRF in the amygdala. The CRF/NPY balance is a leading framework for understanding individual differences in stress vulnerability.
Epilepsy. NPY is released during seizures and suppresses glutamate release via Y2, an endogenous anticonvulsant response.
Bone, immunity and vascular remodelling. NPY receptors are present on osteoblasts and immune cells, and NPY is .
Neuropeptide Y released in the hypothalamus, acting mainly at the Y1 and Y5 receptors. It is among the strongest appetite stimulants known, driving intake up and favouring storage — the opposite end of the axis the gut peptides brake.Schematic — not to scale

3What the research shows

Graded B (observational, strong)

Stress resilience in humans

In studies of soldiers undergoing survival and interrogation training, higher plasma NPY during stress was associated with better performance and fewer dissociative symptoms (Morgan 2000 and 2002, Biol Psychiatry). Lower CSF NPY has been reported in PTSD and in depression. Observational, but consistent and influential. [2]

Intranasal NPY in PTSD

A small randomised, placebo-controlled, single-dose crossover study of intranasal NPY in people with PTSD reported tolerability and signals of reduced anxiety and symptom response to a trauma script (Sayed 2018, Biol Psychiatry). Very small, single-dose, exploratory — proof of concept at most. [3]

Human cardiovascular physiology

Intravenous NPY causes vasoconstriction, raises blood pressure and potentiates noradrenaline's effects; plasma NPY rises with intense sympathetic activation such as exercise, heart failure and myocardial infarction, and has been studied as a prognostic marker.

Appetite and obesity

The feeding effects are overwhelmingly animal data from central administration. On the drug side, Y5 antagonists were taken into human obesity trials — velneperit (S-2367) reached Phase 2 with modest weight effects and was not developed further — and Y2 agonism (the PYY 3-36 route) is the arm that has produced real clinical interest, now mostly as part of combination obesity pharmacology.

Epilepsy

NPY and Y2-targeted gene therapy suppress seizures in rodent models; combined NPY/Y2 and galanin (#156) vectors are an active preclinical strategy for drug-resistant focal epilepsy. No human trial.

Alcohol use, anxiety, depression

Considerable rodent literature linking NPY signalling to alcohol intake and to anxiety- and depression-like behaviour. Human translation limited to the observational and single-dose work above.

4Reported side effects and interactions

Literature-reported

Intravenous NPY raises blood pressure and constricts vessels — this is the expected and limiting peripheral effect. Intranasal single doses in the PTSD study were reported well tolerated, with no serious adverse events, though the sample was tiny. No chronic human safety data exist.

Community-reported

None. Not in self-directed use.

Theoretical. Appetite stimulation is the predictable consequence of Y1/Y5 agonism — the opposite of what most people experimenting with peptides would want. Peripheral vasoconstriction and blood-pressure elevation are real concerns for any systemically administered Y1 , and NPY is also and implicated in vascular remodelling and in some tumour biology (notably neuroblastoma).

Interactions. Additive with sympathomimetics and with noradrenergic drugs on blood pressure. DPP-4 inhibitors alter the NPY-to-NPY 3-36 conversion and therefore the Y1/Y2 balance — a documented pharmacological interaction with unclear clinical significance.

Markers researchers commonly monitor

From the human study protocols and from mechanism:

MarkerWhy it's watched
Blood pressure and heart rateNPY is a vasoconstrictor; this is the primary peripheral safety measure.
Plasma NPYresearch assays; used as a stress-reactivity and prognostic marker rather than a dosing guide.
Validated symptom scales (CAPS, PCL-5, STAI)the psychiatric endpoints in the human work.
Cortisol and ACTHthe CRF/NPY balance framework makes the stress axis the relevant comparator.
Appetite, food intake and body weightthe predictable pharmacodynamic consequence of Y1/Y5 activity.
CBC and CMPgeneral baseline for any investigational peptide.

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

Not applicable as a consumer practice. Human studies used either sterile intravenous preparations under haemodynamic monitoring or a specially formulated intranasal solution designed to exploit nose-to-brain transport, because intravenous NPY does not reach central targets. That delivery problem is the single most important practical fact about this peptide. No calculator preset applies.

6Commonly studied alongside

PYY 3-36 and the Y2 route in appetite research (and so, by extension, the GLP-1 agonists including semaglutide #3); galanin (#156) in epilepsy gene therapy and feeding; CRF and the urocortins (#155) in the stress-balance literature; leptin and AgRP as the other arms of the arcuate circuit.

Informational cross-links. Not stack recommendations.

7Regulatory status by region

RegionStatus (checked —)
United StatesNot FDA-approved; research use only
European UnionNot authorised
United KingdomNot licensed
AustraliaNot approved
South AfricaNot registered
SportNot specifically listed by WADA; an unapproved peptide used for performance or recovery would fall under S0. Check the current list

8Open questions

  • Does intranasal NPY do anything durable in PTSD beyond a single dose? The existing study cannot answer this.
  • Is high NPY a cause of stress resilience or a correlate of it?
  • Can Y-receptor subtype selectivity be achieved well enough to get the central benefit without peripheral vasoconstriction or appetite stimulation?
  • Will NPY/Y2 gene therapy for focal epilepsy reach human trials?

9References

  1. 1Tatemoto K, Carlquist M, Mutt V (1982). Neuropeptide Y — a novel brain peptide with structural similarities to peptide YY and pancreatic polypeptide. Nature. PubMed · DOI
  2. 2Morgan CA 3rd et al. (2000). Plasma neuropeptide-Y concentrations in humans exposed to military survival training. Biol Psychiatry. PubMed · DOI
  3. 3Sayed S et al. (2018). A randomized dose-ranging study of neuropeptide Y in patients with posttraumatic stress disorder. Biol Psychiatry [verify exact title]. PubMed · DOI
  4. 4Heilig M (2004). The NPY system in stress, anxiety and depression. Neuropeptides. PubMed · DOI
  5. 5Reichmann F, Holzer P (2016). Neuropeptide Y: a stressful review. Neuropeptides. PubMed · DOI
  6. 6Noe F et al. (2008). Neuropeptide Y gene therapy decreases chronic spontaneous seizures in a rat model of temporal lobe epilepsy. Brain. PubMed · DOI
  7. 7Zukowska-Grojec Z et al. (1998). Neuropeptide Y: a novel angiogenic factor from the sympathetic nerves and endothelium. Circ Res. PubMed · DOI

† Being confirmed by our reviewers against current sources.

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11Page history

30 Oct 2026Profile published — awaiting medical review

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