glucagon-like-peptide-2 and Hypoglycemia

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.

Topics: Adaptation, Physiological; Animals; Blood Glucose; Body Weight; Cell Proliferation; Diabetes Mellitus, Experimental; Disease Models, Animal; Glucagon; Glucagon-Like Peptide 2; Glucagon-Like Peptide-2 Receptor; Glucose Intolerance; Glucose Tolerance Test; Hypoglycemia; Insulin; Islets of Langerhans; Mice; Mice, Inbred C57BL; Mice, Knockout; Obesity; Receptors, Glucagon; Signal Transduction; Stress, Physiological; Time Factors

Glucagon-like peptide-2 is formed from proglucagon in the intestinal L-cells and is secreted postprandially in parallel with the insulinotropic hormone GLP-1 (glucagon-like peptide-1), which in addition acts to inhibit gastric motility (enterogastrone effect) by inhibiting central parasympathetic outflow. GLP-2 has no effect on the endocrine pancreas. We here tested the hypothesis that GLP-2 acts as an enterogastrone.. Fourteen anesthetized pigs with their splanchnic nerves cut were subjected to insulin hypoglycemia, and force transducers were sutured to the antrum to record motility. GLP-2 was infused intravenously in doses from 1 to 6 pmol/kg/min after the onset of antral motility in response to hypoglycemia.. Insulin hypoglycemia invariably and greatly increased the frequency and amplitude of antral phasic contractions. Infusions of GLP-2 dose dependently (1-6 pmol/kg/min) inhibited antral motility. At 2 pmol/kg/min, resulting in plasma GLP-2 concentrations of 102.5+/-19 pmol/l (normal postprandial range, 30-82 pmol/l), the motility index was inhibited by 91%+/-14%.. Both of the intestinal glucagon-like peptides may operate as hormonal transmitters of the ileal brake effect.

Topics: Animals; Gastric Emptying; Gastrointestinal Hormones; Glucagon-Like Peptide 1; Glucagon-Like Peptide 2; Hypoglycemia; Peptides; Postprandial Period; Pyloric Antrum; Swine