Gastrin-releasing peptide (GRP) is a neuropeptide that stimulates gastrin release. It binds to GRP receptors on St42 human gastric cancer cells with an IC50 value of 0.35 nM. GRP increases contractility of possum (T. vulpecula) gallbladder strips with an EC50 value of 1.34 nM. In vivo, GRP increases gastrin (ED50s = 0.70 and 0.47 nmol/kg2 per hour for peak and integrated values, respectively) and pancreatic polypeptide release (ED50s = 1.2 and 1.01 nmol/kg2 per hour for peak and integrated values, respectively) in conscious cats. It also increases acid and pepsin secretion (ED50s = 1.01 and 2.06 nmol/kg2 per hour, respectively) and increases antral stomach motility in conscious cats. GRP (28 μg/kg) reduces independent ad libitum intake of sucrose and milk from bottles by rats but does not affect intraoral intake of either solution from catheters.