Control Of Insulin Secretion By Cholinergic Signaling In The Human Pancreatic Islet

  1. Alejandro Caicedo1,2,5,6
  1. From the 1Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA
  2. 2Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
  3. 3The Rolf Luft Research Center for Diabetes & Endocrinology, Karolinska Institutet, Stockholm, SE-17177, Sweden
  4. 4Division of Integrative Biosciences and Biotechnology, WCU Program, University of Science and Technology, Pohang, 790-784 Korea
  5. 5Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
  6. 6Program in Neuroscience, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
  1. Corresponding authors: Per-Olof Berggren, per-olof.berggren{at}ki.se, and Alejandro Caicedo, acaicedo{at}med.miami.edu.

Abstract

Acetylcholine regulates hormone secretion from the pancreatic islet and is thus crucial for glucose homeostasis. Little is known, however, about acetylcholine (cholinergic) signaling in the human islet. We recently reported that in the human islet acetylcholine is primarily a paracrine signal released from alpha cells rather than primarily a neural signal as in rodent islets. Here we demonstrate that the effects acetylcholine produces in the human islet are different and more complex than expected from studies conducted on cell lines and rodent islets. We found that endogenous acetylcholine not only stimulates the insulin-secreting beta cell via the muscarinic acetylcholine receptors M3 and M5, but also the somatostatin-secreting delta cell via M1 receptors. Because somatostatin is a strong inhibitor of insulin secretion, we hypothesized that cholinergic input to the delta cell indirectly regulates beta cell function. Indeed, when all muscarinic signaling was blocked, somatostatin secretion decreased and insulin secretion unexpectedly increased, suggesting a reduced inhibitory input to beta cells. Endogenous cholinergic signaling therefore provides direct stimulatory and indirect inhibitory input to beta cells to regulate insulin secretion from the human islet.

  • Received September 5, 2013.
  • Accepted March 15, 2014.

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  1. Diabetes
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