PYY (3-36)
endogenous
What it isPeptide YY, released by ileal and colonic L cells in proportion to calories eaten; the (3‑36) form acts at Y2.
Why this oneIt is the ileal brake — it slows transit and reduces appetite, and it rises durably after bariatric surgery.
What limits itY2 is presynaptic, so PYY(3–36) reduces NPY release: the same receptor family, opposite effect on feeding.
NO BOXED WARNINGS