Glucagon‐like peptide‐1(7–36) amide is a new incretin/enterogastrone candidate

Cloning and sequence analysis of cDNAs and DNA fragments from genomic libraries has led to a dramatic increase in understanding of the glucagon-related peptides in recent years. The primary structure of the biosynthetic precursor of glucagon (preproglucagon) has been elucidated. The complex structural connec- tions between the multiple molecular forms of the glucagon-like peptides in tissues and in the circulation have been determined [ 1,2]. Mammalian proglucagon consists of 160 amino acid residues and is synthesized in the islets of Langerhans, intestine and brain. An exciting recent finding is that in addition to glucagon the preproglucagon gene in mammals encodes two additional peptides with struc- tural similarity to glucagon, termed glucagon-like peptide-1 and -2 (GLP-I and GLP-2). The truncated form of GLP-1, GLP-1(7-36) amide, which is secreted by the mammalian intestine, strongly stimulates insu- lin secretion and inhibits gastric acid secretion. This review focuses mainly on the truncated form of GLP-1. since a rapidly increasing number of reports indicate a remarkable interest of investigators in this particular hormone, which actually fulfills the classical role of an ‘enterogastrone’ and ‘incretin’ hormone. The purpose here is to describe what is known so far about the origin, processing, organ distribution and actions of this peptide and to search for promising future direc- tions of further investigations.