Glucagon-like peptide-2 receptor modulates islet adaptation to metabolic stress in the ob/ob mouse

Glucagon-like peptide-2 (GLP-2) is a gut hormone that increases gut growth, reduces mucosal cell death, and augments mesenteric blood flow and nutrient absorption. Exogenous GLP-2(1-33) also stimulates glucagon secretion and enhances gut barrier function with implications for susceptibility to systemic inflammation and subsequent metabolic dysregulation. We examined the importance of GLP-2 receptor (GLP-2R) signaling for glucose homeostasis in multiple models of metabolic stress, diabetes, and obesity.

Body weight, islet function, glucose tolerance, and islet histology were studied in wild-type, high-fat fed, lean diabetic, Glp2r(-/-) and ob/ob:Glp2r(-/-) mice.

GLP-2 did not stimulate glucagon secretion from isolated pancreatic islets in vitro, and exogenous GLP-2 had no effect on the glucagon response to insulin-induced hypoglycemia in vivo. Glp2r(-/-) mice exhibit no change in glycemia, and plasma glucagon levels were similar in Glp2r(-/-) and Glp2r(+/+) mice after hypoglycemia or after oral or intraperitoneal glucose challenge. Moreover, glucose homeostasis was comparable in Glp2r(-/-) and Glp2r(+/+) mice fed a high-fat diet for 5 months or after induction of streptozotocin-induced diabetes. In contrast, loss of the GLP-2R leads to increased glucagon secretion and alpha-cell mass, impaired intraperitoneal glucose tolerance and hyperglycemia, reduced beta-cell mass, and decreased islet proliferation in ob/ob:Glp2r(-/-) mice.

Our results show that, although the GLP-2R is not critical for the stimulation or suppression of glucagon secretion or glucose homeostasis in normal or lean diabetic mice, elimination of GLP-2R signaling in obese mice impairs the normal islet adaptive response required to maintain glucose homeostasis.