Bombesin

Bombesin is a tetradecapeptide isolated from amphibian skin, which is biologically active in both the central nervous system and gastrointestinal tract. It has two known homologs in mammals called neuromedin B and gastrin-releasing peptide. It stimulates gastrin release from G cells. It activates three different G-protein-coupled receptors known as BBR1, -2, and -3. It also activates these receptors in the brain.