Intestinotrophic Glucagon-Like Peptide-2 (GLP-2) Activates Intestinal Gene Expression and Growth Factor-Dependent Pathways Independent of the Vasoactive Intestinal Peptide Gene in Mice

The enteroendocrine and enteric nervous systems convey signals through an overlapping network of regulatory peptides that act either as circulating hormones or as localized neurotransmitters within the gastrointestinal tract. Because recent studies invoke an important role for vasoactive intestinal peptide (VIP) as a downstreammediator of glucagon-like peptide-2 (GLP-2) action in the gut, we examined the importance of the VIP-GLP-2 interaction through analysis of Vip/ mice. Unexpectedly, we detected abnormal villous architecture, expansion of the crypt compartment, increased crypt cell proliferation, enhanced Igf1 andKgf gene expression, and reduced expression of Paneth cell products in the Vip/ small bowel. These abnormalities were not reproduced by antagonizing VIP action in wild-type mice, and VIP administration did not reverse the intestinal phenotype of Vip/ mice. Exogenous administration of GLP-2 induced the expression of ErbB ligands and immediate-early genes to similar levels in Vip/ vs. Vip/ mice. Moreover, GLP-2 significantly increased crypt cell proliferation and small bowel growth to comparable levels in Vip/ vs. Vip/mice. Unexpectedly, exogenous GLP-2 administration had no therapeutic effect in mice with dextran sulfate-induced colitis; the severity of colonic injury and weight loss was modestly reduced in female but not male Vip/mice. Taken together, these findings extend ou