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Incretins such as glucagon-like peptide 1 (GLP-1) are released from the gut and potentiate insulin release in a glucose-dependent manner. Although this action is generally believed to hinge on cAMP and protein kinase A signaling, up-regulated beta cell intermediary metabolism may also play a role in incretin-stimulated insulin secretion. By employing recombinant probes to image ATP dynamically in situ within intact mouse and human islets, we sought to clarify the role of GLP-1-modulated energetics in beta cell function. Using these techniques, we show that GLP-1 engages a metabolically coupled subnetwork of beta cells to increase cytosolic ATP levels, an action independent of prevailing energy status. We further demonstrate that the effects of GLP-1 are accompanied by alterations in the mitochondrial inner membrane potential and, at elevated glucose concentration, depend upon GLP-1 receptor-directed calcium influx through voltage-dependent calcium channels. Lastly, and highlighting critical species differences, beta cells within mouse but not human islets respond coordinately to incretin stimulation. Together, these findings suggest that GLP-1 alters beta cell intermediary metabolism to influence ATP dynamics in a species-specific manner, and this may contribute to divergent regulation of the incretin-axis in rodents and man.

Original publication

DOI

10.1210/me.2014-1038

Type

Journal article

Journal

Mol Endocrinol

Publication Date

06/2014

Volume

28

Pages

860 - 871

Keywords

Adenosine Triphosphate, Adult, Animals, Calcium Signaling, Energy Metabolism, Glucagon-Like Peptide 1, Glucagon-Like Peptide-1 Receptor, Glucose, Humans, Incretins, Insulin-Secreting Cells, Membrane Potential, Mitochondrial, Mice, Middle Aged, Receptors, Glucagon, Species Specificity, Tissue Culture Techniques