Pancreatic polypeptide (PP)
Also known as: PP
A 36-amino-acid peptide from islet PP (F) cells, released after meals under vagal control, that inhibits exocrine pancreatic secretion and gallbladder contraction and contributes to satiety.
Overview
Pancreatic polypeptide belongs to the PP-fold family with peptide YY and neuropeptide Y. PP cells are concentrated in the posterior head and uncinate process, derived from the ventral pancreatic bud. Secretion rises sharply after a meal (especially protein), with fasting, exercise and hypoglycaemia, and depends heavily on vagal cholinergic input. It acts on Y4 (and Y5) receptors, Gi-coupled GPCRs.
Its effects are inhibitory: reduced pancreatic enzyme and bicarbonate secretion, gallbladder relaxation and, centrally, reduced food intake.
- Location
Source: PP (F/γ) cells of islets in the head/uncinate process of the pancreas. Targets: exocrine pancreas, gallbladder, brainstem/hypothalamus.
Function
- Inhibits exocrine pancreatic secretion.
- Relaxes the gallbladder.
- Promotes satiety.
- Physiology
Class: peptide (36 aa). Receptor: Y4/Y5 — Gi.
- Regulation
Stimulated by protein meals, fasting, exercise and hypoglycaemia via the vagus; abolished by vagotomy (the "sham-feeding PP test" assesses vagal integrity).
Clinical significance
Neuroendocrine tumour marker
Raised in many pancreatic neuroendocrine tumours (including non-functioning ones and PPomas); low PP responses occur in chronic pancreatitis and pancreatogenic (type 3c) diabetes.
Compiled from standard anatomy and physiology references — see the Endocrine System sources. For education only; not medical advice.