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Curcumin is a direct inhibitor of glucose transport in adipocytes

Allan Green1, Jean Krause2, John M Rumberger2

  • 1Department of Chemistry & Biochemistry, SUNY Oneonta, Oneonta, NY 13820, USA.

Phytomedicine : International Journal of Phytotherapy and Phytopharmacology
|September 25, 2013
PubMed

Insights

Curcumin directly inhibits glucose transporters in rat adipocytes, impacting both basal and insulin-stimulated glucose uptake. This study clarifies curcumin's mechanism, showing it doesn't affect insulin signaling pathways.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Pharmacology

Background:

  • Curcumin, a compound from turmeric, has shown complex effects on cellular processes.
  • Previous studies suggested curcumin might interfere with insulin signaling and glucose transporter type 4 (GLUT4) translocation in adipocytes.

Purpose of the Study:

  • To investigate the precise mechanism by which curcumin affects glucose transport and insulin signaling in primary rat adipocytes.
  • To determine if curcumin's inhibitory effects on glucose uptake are mediated through insulin signaling pathways or direct interaction with glucose transporters.

Main Methods:

  • Primary rat adipocytes were treated with varying concentrations of curcumin.
  • Glucose transport was measured using 2-deoxyglucose uptake assays under basal and insulin-stimulated conditions.
  • Lipolysis was assessed to evaluate effects on a separate insulin-regulated pathway.
  • Phosphorylation of Akt at serine 473 was analyzed to probe insulin signaling.
  • Time-course and pre-incubation experiments were conducted to understand the kinetics of curcumin's action.

Main Results:

  • Curcumin significantly inhibited both basal and insulin-stimulated glucose transport in a dose-dependent manner.
  • Curcumin did not affect insulin's ability to inhibit lipolysis, indicating pathway specificity.
  • The inhibitory effect of curcumin on glucose transport was rapid, observed within 30 seconds.
  • Curcumin did not alter the insulin-stimulated phosphorylation of Akt, a key component of insulin signaling.
  • Inhibition of glucose transport occurred regardless of pre-incubation time, suggesting a direct effect.

Conclusions:

  • Curcumin acts as a direct inhibitor of glucose transporters in rat adipocytes.
  • The inhibitory action of curcumin on glucose transport is independent of the classical insulin signaling pathway.
  • These findings provide a clearer understanding of curcumin's molecular targets in glucose metabolism regulation.
Keywords:
AdipocytesCurcuminGlucose transportInsulin actionLipolysis

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