Peptide directoryGut, pancreas & liver

Gastrin-releasing peptide

It releases gastrin, carries itch, and its precursor marks small-cell lung cancer.

Where it comes from

Made in
Nerves of the stomach and gut, neuroendocrine cells of the lung, brain
Sent out by
Vagal stimulation in the stomach; local signals in the lung
Acts on
  • G cells (gastrin release)
  • Pancreas
  • Gut smooth muscle
  • Itch and fear circuits in the spinal cord and amygdala

What it does

  • Releases gastrin and so acid
  • Stimulates pancreatic secretion and gut contraction
  • Carries itch signals in the spinal cord 1
  • Drives the growth of some tumours, small-cell lung cancer above all 2

In medicine

  • Pro-GRP in blood is a tumour marker for small-cell lung cancer, and it falls with chemoradiotherapy in step with how long patients live 2
  • GRPR-targeted PET tracers image prostate and breast cancer in trials

Beyond the body’s own use

  • GRP receptor blockers were trialled against lung cancer in the 1990s without success. Radioligands aimed at the same receptor are the current line, and are still in imaging and early treatment trials rather than in use 2
  • The itch pathway was found by deleting the receptor in mice, which left them scratching far less while their response to pain was unchanged 1; drugs against it remain in animals

Sources

  1. Sun & Chen, A gastrin-releasing peptide receptor mediates the itch sensation in the spinal cord, Nature 2007
  2. Grønberg et al., Progastrin-releasing peptide and survival in limited-stage small-cell lung cancer, Lung Cancer 2025

This card describes what a medicine is for and what the evidence says; it recommends nothing. Talk to your clinician about anything you read here.