Gastrin releasing peptide (GRP) regulates gastric acid secretion and motor function by promoting the relase of gastrin. GRP also is involved in the circadian system and also seems to mediate some aspects of stress. Spindel, ER; et al., Proc. Natl. Acad. Sci. USA, 81, 5699, (1984); Merali, Z; et al., Neuropeptides, 33, 376 (1999).