ABSTRACT
Cell proliferation is one aspect of an integrated growth process which also involves tissue differentiation, maturation, and cell migration. This chapter provides an evidence to support a role for locally secreted neuropeptides in both normal and neoplastic gastrointestinal and neuronal development. Endogenous hypergastrinemia induced by antral exclusion or small bowel resection in rat’s increased DNA synthesis within chemically induced tumors of the colon, demonstrating a likely trophic action of gastrin in vivo. Gastrin stimulated the growth of human stomach and colon carcinomas transplanted into nude mice, although growth was inhibited by secretin. The balance of evidence supports a role for certain neuropeptides during normal gastrointestinal growth and development mediated by local paracrine actions in the vicinity of their neuroendocrine sites of synthesis. Peptides such as gastrin releasing peptide, vasoactive intestinal polypeptide, gastrin/cholecystokinin and gastrin interact with specific cell membrane receptor populations and activate well-recognized series of intracellular messenger systems, including proto-oncogene expression, which precede DNA synthesis.
