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alpha-lipoic acid regulates AMP-activated protein kinase and inhibits insulin secretion from beta cells

E D Targonsky1, F Dai, V Koshkin

  • 1Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON, Canada, M5S 1A8.

Diabetologia
|June 6, 2006
PubMed
Abstract

Insights

Alpha-lipoic acid (alpha-LA) impacts pancreatic beta cells, reducing insulin secretion and growth with chronic use. Acute alpha-LA also inhibits insulin secretion, potentially via mitochondrial dysfunction.

Area of Science:

  • Endocrinology
  • Metabolism
  • Cell Biology

Background:

  • Alpha-lipoic acid (alpha-LA) is an antioxidant with demonstrated antidiabetic and anti-obesity effects.
  • In the hypothalamus, alpha-LA inhibits AMP-activated protein kinase (AMPK) to suppress appetite and prevent obesity.
  • AMPK plays a crucial role in pancreatic beta cell function, making alpha-LA a potential therapeutic agent for type 2 diabetes and obesity.

Purpose of the Study:

  • To investigate the direct effects of alpha-lipoic acid (alpha-LA) on pancreatic beta cell function.
  • To determine how alpha-LA influences insulin secretion, AMPK signaling, mitochondrial function, and cell growth in beta cells.

Main Methods:

  • Isolated rat islets and MIN6 beta cells were treated with alpha-LA, AICAR, or metformin.
  • Treatments were acute (15-90 min) or chronic (18-24 h).
  • Assessed insulin secretion, AMPK pathway phosphorylation, mitochondrial function (ROS, depolarization), and cell growth.

Main Results:

  • Alpha-lipoic acid (alpha-LA) dose-dependently increased AMPK and ACC phosphorylation in beta cells.
  • Chronic alpha-LA, AICAR, and metformin reduced insulin secretion.
  • Acute alpha-LA inhibited insulin secretion, increased reactive oxygen species (ROS), and impaired mitochondrial function, unlike AICAR and metformin.

Conclusions:

  • This study demonstrates alpha-lipoic acid (alpha-LA) directly impacts pancreatic beta cell function.
  • Chronic alpha-LA exposure leads to AMPK activation, reduced insulin secretion and content, and inhibited cell growth.
  • Acute alpha-LA inhibits insulin secretion, likely through ROS-induced mitochondrial impairment.

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