Journal of Nutritional Science and Vitaminology
Online ISSN : 1881-7742
Print ISSN : 0301-4800
ISSN-L : 0301-4800
Review
Physiologic Implications of Phosphoinositides and Phospholipase C in the Regulation of Insulin Secretion
Hanae YAMAZAKIKathleen C. ZAWALICHWalter S. ZAWALICH
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2010 Volume 56 Issue 1 Pages 1-8

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Abstract

The secretion of insulin from the pancreatic β-cell must be commensurate to satisfy the insulin requirements of the organism. This cell has a great flexibility to meet these requirements which are increased not only by the ingestion of nutrients (increase of plasma glucose) but also by the sensitivity of target tissues to insulin as well. The insulin secretion is a complex biochemical event regulated by a host of potential second messenger molecules acting alone or in concert. These events include the cation calcium, which gains access to the β-cell via the opening of voltage-regulated channels, cAMP and phosphoinositide-derived second messenger molecules, generated as a consequence of phospholipase C (PLC) activation. In this review, we focused on phosphoinositides, PLC/Phosphokinase C (PKC) and phosphatidylinositol 3-kinase (PI3K) cascade in the regulation of insulin secretion. We also described our studies on the mechanism of the β-cell desensitization using perifused islets. It is suggested that a failure of the signaling events contribute to the pathogenesis of diabetes in which the β-cell can no longer secrete the required amounts of insulin. It has been observed that chronic exposure to high glucose desensitizes the β-cells to subsequent stimulation. We suggested that the failure of PLC activation can be attributed in the impairment of insulin secretion by chronic sustained glucose exposure. It may contribute to the vicious circle of impaired insulin secretion leading up to diabetes.

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© 2010 by the Center for Academic Publications Japan
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