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Long-term ethanol exposure inhibits glucose transporter 4 expression via an AMPK-dependent pathway in adipocytes

Li Feng1, Yong-feng Song, Qing-bo Guan

  • 1Provincial Hospital Affiliated to Shandong University, Institute of Endocrinology, Shandong Academy of Clinical Medicine, Ji-nan, China.

Acta Pharmacologica Sinica
|February 23, 2010
PubMed
Abstract

Insights

Ethanol consumption impairs glucose regulation by inhibiting the AMPK/MEF2/GLUT4 pathway in adipocytes, reducing glucose transporter 4 (GLUT4) expression and insulin sensitivity.

Area of Science:

  • Metabolic signaling pathways
  • Cellular response to ethanol
  • Glucose homeostasis

Background:

  • The AMP-activated protein kinase (AMPK) and myocyte enhancer factor 2 (MEF2) isoforms' roles in ethanol's effects on glucose transporter 4 (GLUT4) are not fully understood.
  • Investigating these molecular mechanisms is crucial for understanding ethanol-induced metabolic dysfunction.

Purpose of the Study:

  • To elucidate the roles of AMPK and MEF2 isoforms in mediating ethanol's impact on GLUT4 expression in adipocytes.
  • To investigate the in vivo and in vitro effects of ethanol on the AMPK/MEF2/GLUT4 pathway.

Main Methods:

  • Male Wistar rats received daily ethanol doses (0, 0.5, or 5 g/kg) for 22 weeks, with AMPK, MEF2 (A and D), and GLUT4 expression analyzed.
  • Experiments in isolated rat and human adipocytes involved treatments with ethanol, AICAR (AMPK activator), and compound C (AMPK inhibitor).
  • Gene and protein expression levels were quantified using RT-PCR and Western blotting.

Main Results:

  • Long-term ethanol exposure significantly reduced activated AMPK, MEF2A, MEF2D, and GLUT4 expression in rat adipose tissue.
  • In adipocytes, compound C blocked AICAR-induced AMPK activation and subsequent increases in MEF2 and GLUT4 expression.
  • In vitro ethanol treatment suppressed the AMPK/MEF2/GLUT4 signaling pathway.

Conclusions:

  • The AMPK/MEF2/GLUT4 pathway is present in rat and human adipocytes, with activated AMPK positively regulating MEF2 and GLUT4.
  • Ethanol disrupts this pathway, leading to decreased GLUT4 expression, impaired insulin sensitivity, and reduced glucose tolerance.

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