BIOMOLECULAR ADVANCES IN GASTROINTESTINAL HORMONES

Gastrointestinal hormones are chemical messengers that regulate a broa d range of physiologic functions.1 Although primarily expressed within tissues of the gut, these peptide hormones are widely distributed thr oughout the body and act on multiple target tissues.2 Furthermore, the se regulatory peptides can exist in multiple molecular forms that may bind to multiple cell-surface receptors coupled to one of several poss ible signal transduction systems leading to diverse biologic responses . With such an expansive field to study, it is not surprising that gut endocrinologists have embraced the new techniques that are emerging f rom the revolution of molecular biology. Beginning with the first cons truction of a recombinant DNA molecule by Paul Berg in 1971, molecular biology has developed many new techniques3 that have been rapidly ado pted by gut endocrinologists to enable a more detailed understanding o f gastrointestinal function. The merging of these two fields has led t o a new area of research, molecular gut endocrinology, or the study of gut physiology and endocrinology at the level of individual molecules (ranging from polypeptide-surface receptors to small-molecule second messengers to DNA sequences). Gut cells are constantly bombarded by nu merous hormones, and the tightly regulated physiologic status of each cell is becoming more clearly understood.