What it is
Peptide YY is a gut hormone of 36 amino acids. It was found in 1982 by Kazuhiko Tatemoto, who screened pig intestine extracts for peptides ending in an amidated amino acid and found one ending in tyrosine amide — tyrosine's one-letter code is Y, and the human sequence begins and ends with one (Tatemoto, PNAS, PMID 6953409). He noted its resemblance to pancreatic polypeptide and proposed the two "form a new peptide family"; the same year his group described neuropeptide Y, a brain peptide with "structural similarities" to both (Tatemoto, Nature, PMID 6896083).
| Human PYY (UniProt P10082) | |
|---|---|
| Precursor | 97 residues |
| PYY (1–36) | residues 29–64, 36 amino acids, tyrosine amide at the end |
| PYY3-36 | residues 31–64, 34 amino acids — the short form that acts on the Y2 receptor |
Both forms sit well under the 40-residue line US rules use for proteins.
What it does
PYY is released from the gut after food arrives, like GLP-1. A 2002 Nature paper (Batterham et al., PMID 12167864) set out the pathway now most cited:
- PYY3-36 is released "in proportion to the calorie content of a meal".
- It acts on the Y2 receptor on appetite-promoting neuropeptide Y neurons in the hypothalamus, quietening them and so freeing the neighbouring POMC neurons that suppress appetite.
- In rats and mice injected PYY3-36 reduced food intake — but not in mice lacking the Y2 receptor.
UniProt's annotation adds older roles from animal work: PYY inhibits the pancreas's digestive secretions (Tatemoto's original finding, in cats) and helps set fluid secretion and contraction in the colon.
The human studies
Two small infusion studies are the core of the human record:
| Study | Who | Design | Result |
|---|---|---|---|
| Batterham 2002, Nature | volunteers | after-meal levels of PYY3-36 infused | food intake −33% over 24 hours |
| Batterham 2003, NEJM (PMID 12954742) | 12 obese + 12 lean | double-blind, placebo-controlled crossover | buffet lunch two hours later −30% (obese), −31% (lean); 24-hour intake also down |
The 2003 study asked whether obese people resist PYY the way they resist leptin. They did not. It also found lower PYY levels in the obese group (fasting 10.2 vs 16.9 pmol per litre). Both were single infusion sessions, not treatment trials, and they say nothing about weight over months.
Why there is no PYY drug
FDA's approved-drug data (openFDA Drugs@FDA, checked 2026-11-02) return no product with peptide YY as an active ingredient. The GLP-1 drugs reached the market instead; this record does not establish why PYY did not. PubMed indexes 490 randomised trials naming PYY in the title or abstract; this library did not read them one by one and does not characterise them here.
Where it stands
- Not a medicine. A gut hormone studied as an appetite signal.
- Research volume: 4,362 PubMed records for peptide YY or PYY in the title or abstract, 490 indexed as randomised trials; ClinicalTrials.gov lists 409 studies under the full name and 68 under "PYY 3-36" (searched 2026-11-02).
Related reading
Ghrelin, the stomach's pre-meal hunger signal, does the opposite — it rises before meals. Cholecystokinin is the faster fullness signal from the upper gut, and the GLP-1 entry covers the hormone released alongside PYY that became a class of drugs.