Glucose homeostasis
The glucose tolerance test (intraperitoneal or oral) is commonly used in the diagnosis of diabetes in both humans and rodents. The ability to quickly normalize the hyperglycemic episode following administration of a glucose bolus provides integrated information about glucose-induced insulin secretion by the pancreatic B cells and insulin sensitivity in the liver and peripheral organs. In addition, an oral (versus intraperitoneal) administration of glucose stimulates intestinal secretion of powerful insulinotropic hormones, the incretins, GLP-1 and GIP.
Diabetes is associated with alterations in several physiological functions. Thus, the glucose tolerance test is generally coupled with other tests in order to dissect out the contribution of each individual alteration.
For example, a primary defect at the level of incretin secretion or action is diagnosed with an impaired oral glucose tolerance in face of a normal intraperitoneal glucose tolerance. An impaired intraperitoneal glucose tolerance will suggest impairments in either insulin secretion or insulin sensitivity (or both together). It is, therefore, often coupled with an insulin tolerance test. Whenever a defect in insulin secretion is suspected, B cell function can be further assessed ex vivo in static infusions or perifusions of isolated islets.
A minimum of 10 mice per group should be sent to our facility, one week prior to the experiment.
Price per mouse : CHF 15.-
References :
Preitner F, Ibberson M, Franklin I, Binnert C, Pende M, Gjinovci A, Hansotia T, Drucker DJ, Wollheim C, Burcelin R, Thorens B. Gluco-incretins control insulin secretion at multiple levels as revealed in mice lacking GLP-1 and GIP receptors. J Clin Invest. 2004 Feb;113(4):635-45.
Burcelin R, Crivelli V, Dacosta A, Roy-Tirelli A, Thorens B. Heterogeneous metabolic adaptation of C57BL/6J mice to high-fat diet. Am J Physiol Endocrinol Metab. 2002 Apr;282(4):E834-42.
Stumpel F, Burcelin R, Jungermann K, Thorens B. Normal kinetics of intestinal glucose absorption in the absence of GLUT2: evidence for a transport pathway requiring glucose phosphorylation and transfer into the endoplasmic reticulum. Proc Natl Acad Sci U S A. 2001 Sep 25;98(20):11330-5.
The insulin tolerance test (ITT) is commonly used in rodents to evaluate insulin sensitivity. The ability of the intraperitoneal insulin load to induce hypoglycemia is an index of insulin sensitivity. There are, however, several confounding factors including differential basal glucose between groups, counteracting effects of counterregulation, and effects of acute handling stress. Therefore, when alterations in insulin sensitivity (resistance or hypersensitivity) are suspected on the basis of an ITT, a more reliable, quantitative analysis is performed using the euglycemic, hyperinsulinemic clamp technique.
A minimum of 10 mice per group should be sent to our facility, one week prior to the experiment.
Price per mouse : CHF 15.-
Euglycemic, hyperinsulinemic clamp
The measure of insulin sensitivity relies on establishing a quantitative relationship between plasma insulin and measurable insulin actions. However, in vivo the ever present feedback relationship between glucose (to stimulate insulin secretion) and insulin (to lower blood glucose) complicates the analysis of individual contributions of insulin resistance and B cell unresponsiveness to diseases such as type 2 diabetes.
The euglycemic hyperinsulinemic clamp has been designed to open this loop, and provide quantitative measurements of insulin sensitivity in conditions where both glycemia and hyperinsulinemia are set at constant, measurable levels. The amount of glucose infused in order to maintain euglycemia in face of the achieved hyperinsulinemia is a direct measurement of insulin sensitivity.
Combined with the use of glucose tracers, the clamp technique allows assessment of whole-body and tissue-specific insulin action on glucose fluxes and glucose metabolism, including :
- Basal and insulin-stimulated hepatic glucoseproduction.
- Insulin-stimulated whole-body glucose uptake, glycolysis, and glycogen/lipid synthesis.
- Insulin-stimulated glucose uptake, glycolysis, and glycogen synthesis in individual tissues (e.g., skeletal muscle, adipose tissue (WAT, BAT), heart, brain).
An indwelling femoral vein catheter is placed 4 to 7 days prior to the experiment. The clamp is performed in 5 hour-fasted, awake and free-moving mice. The rate of insulin infusion is tailored (between 2.5 and 20mU/kg.min) to the metabolic parameter of interest. Lowest doses of insulin are best suited to assess insulin sensitivity in the liver, whereas high doses are best to assess insulin sensitivity in muscle. Choice of the insulin dose will also take into account age, sex and strain differences.
Ten to 12 mice per group should be sent to our facility, one week prior to the experiment. In some cases, an additional, smaller cohort might be required to complete the experiment.
Price per mouse : CHF 200.-
References :
Cook S, Hugli O, Egli M, Menard B, Thalmann S, Sartori C, Perrin C, Nicod P, Thorens B, Vollenweider P, Scherrer U, Burcelin R. Partial gene deletion of endothelial nitric oxide synthase predisposes to exaggerated high-fat diet-induced insulin resistance and arterial hypertension. Diabetes. 2004 Aug;53(8):2067-72.
Burcelin R, Crivelli V, Dacosta A, Roy-Tirelli A, Thorens B. Heterogeneous metabolic adaptation of C57BL/6J mice to high-fat diet. Am J Physiol Endocrinol Metab. 2002 Apr;282(4):E834-42.
Duplain H, Burcelin R, Sartori C, Cook S, Egli M, Lepori M, Vollenweider P, Pedrazzini T, Nicod P, Thorens B, Scherrer U. Insulin resistance, hyperlipidemia, and hypertension in mice lacking endothelial nitric oxide synthase. Circulation. 2001 Jul 17;104(3):342-5.
Hyperglycemic clamp
The hyperglycemic clamp allows assessment of in vivo pancreatic b-cell function, i.e., glucose-induced insulin secretion. Five hour-fasted, awake and free-moving mice receive a glucose infusion through a femoral vein indwelling catheter. Infusion rates are adjusted in order to maintain the blood glucose concentration at either 10 or 20 mM, as determined from tail vein blood. After 180 min of glucose clamp, blood is collected for measurement of plasma insulin levels. Alternatively, a plasma insulin profile can be assessed from frequent blood samplings through an arterial line.
Ten to 12 mice per group should be sent to our facility, one week prior to the experiment. In some cases, an additional, smaller cohort might be required to complete the experiment.
Price per mouse : CHF 100.-
References :
Burcelin R, Thorens B. Evidence that extrapancreatic GLUT2-dependent glucose sensors control glucagon secretion. Diabetes. 2001 Jun;50(6):1282-9
Thorens B, Guillam MT, Beermann F, Burcelin R, Jaquet M. Transgenic reexpression of GLUT1 or GLUT2 in pancreatic beta cells rescues GLUT2-null mice from early death and restores normal glucose-stimulated insulin secretion. J Biol Chem. 2000 Aug 4;275(31):23751-8.
Hypoglycemic, hyperinsulinemic clamp
To study the counterregulatory response to hypoglycemia, 6 hour fasted, awake and freely moving mice are subjected to hyperinsulinemic (18 mU · kg–1 · min–1) -hypoglycemic (2-2.5 mmol/l) clamps. A glucose solution is co-infused with insulin to maintain blood glucose levels at the target value during the experimental period. After completion of the infusions, blood is collected for determination of plasma levels of counterregulatory hormones (e.g. glucagon).
Ten mice should be sent to our facility, one week prior to the experiment. In some cases, an additional, smaller cohort might be required.
Price per mouse : CHF 100.-
References :
Burcelin R, Thorens B. Evidence that extrapancreatic GLUT2-dependent glucose sensors control glucagon secretion. Diabetes. 2001 Jun;50(6):1282-9
Thorens B, Guillam MT, Beermann F, Burcelin R, Jaquet M. Transgenic reexpression of GLUT1 or GLUT2 in pancreatic beta cells rescues GLUT2-null mice from early death and restores normal glucose-stimulated insulin secretion. J Biol Chem. 2000 Aug 4;275(31):23751-8.
Isolated islets static infusions or perifusions
Isolation of murine pancreatic islets
Pancreatic islets are isolated from control or genetically-modified mice after digestion of the whole pancreas by ductal injection of collagenase. Islets are purified by hand-picking or by density centrifugation. Islet yield (50-200 islets/mouse pancreas) will strongly vary depending on mice age (optimal around 2-3 months), strain, and potential deleterious effects of the genetic manipulation on the pancreatic structure.
The number of mice should be discussed and will vary according to the experimental design and the mouse strain.
Price : please contact us
Measurement of insulin secretion by pancreatic islets
Perifusions or static incubations of islets are performed to establish secretory responses to substrates such as glucose, to neurotransmitters such as acetylcholine, or to incretin factors such as GLP1 and GIP.
Perifusion of islets allows for dynamic characterization of glucose-stimulated insulin secretion. After the experiment, total islet insulin content is measured. Isolated islets can also be analyzed for second messengers such as cAMP.
The number of experiments should be discussed and will vary according to the experimental design and the mouse strain.
Price : please contact us
References :
Preitner F, Ibberson M, Franklin I, Binnert C, Pende M, Gjinovci A, Hansotia T, Drucker DJ, Wollheim C, Burcelin R, Thorens B. Gluco-incretins control insulin secretion at multiple levels as revealed in mice lacking GLP-1 and GIP receptors. J Clin Invest. 2004 Feb;113(4):635-45.
Thorens B, Guillam MT, Beermann F, Burcelin R, Jaquet M. Transgenic reexpression of GLUT1 or GLUT2 in pancreatic beta cells rescues GLUT2-null mice from early death and restores normal glucose-stimulated insulin secretion. J Biol Chem. 2000 Aug 4;275(31):23751-8.
Guillam MT, Hummler E, Schaerer E, Yeh JI, Birnbaum MJ, Beermann F, Schmidt A, Deriaz N, Thorens B. Early diabetes and abnormal postnatal pancreatic islet development in mice lacking Glut-2. Nat Genet. 1997 Nov;17(3):327-30. Erratum in: Nat Genet 1997 Dec;17(4):503.
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