Short-term AMP-regulated protein kinase activation enhances insulin-sensitive fatty acid uptake and increases the effects of insulin on fatty acid oxidation in L6 muscle cells

Exp Biol Med (Maywood). 2010 Apr;235(4):514-21. doi: 10.1258/ebm.2009.009228.

Abstract

Evidence shows that exercise increases insulin-sensitive glucose uptake and that exercise-induced AMP-regulated protein kinase (AMPK) activation is a likely candidate to mediate this metabolic adaptation. The purpose of this study was to determine whether repeated AMPK activation can similarly enhance insulin-sensitive fatty acid (FA) metabolism. L6 myotubes were incubated under the following conditions: repeated plus acute 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) treatment (RAA; 1 mmol/L AICAR for 5 h/d for 5 days plus 1 mmol/L AICAR for 60 min on day 6), repeated AICAR (RA; 1 mmol/L AICAR for 5 h/d for five days) or acute AICAR (AA; 1 mmol/L AICAR for 60 min) and were compared with control cells that were not treated with AICAR. On day six, cells from each group were incubated with or without 100 nmol/L insulin. AICAR treatment and insulin stimulation independently increased (P < 0.05) palmitate uptake in all groups. RAA potentiated the insulin-induced increase in palmitate uptake by 97% (P < 0.05) as compared with control cells. RA and AA treatments prevented the insulin-induced decrease in palmitate oxidation, while RAA treatment restored the sensitivity of the cells to insulin action on palmitate oxidation. Total peroxisome proliferator-activated receptor-gamma co-activator-1 alpha, atypical protein kinase C-zeta, cytochrome C and CD36 protein content was increased (P < 0.05) by RA treatment, but unaffected by insulin. These results indicate that repeated AMPK activation induces improvements in insulin-sensitive FA uptake and oxidation and that this occurs partly via changes in the expression of proteins linked to insulin signaling and FA uptake and oxidation capacity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / metabolism*
  • Aminoimidazole Carboxamide / analogs & derivatives
  • Aminoimidazole Carboxamide / pharmacology
  • Animals
  • Cell Line
  • Enzyme Activation
  • Fatty Acids / chemistry
  • Fatty Acids / metabolism*
  • Humans
  • Hypoglycemic Agents / pharmacology
  • Insulin / metabolism*
  • Muscle, Skeletal / cytology
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / metabolism*
  • Oxidation-Reduction
  • Palmitates / chemistry
  • Palmitates / metabolism
  • Rats
  • Ribonucleotides / pharmacology
  • Signal Transduction / physiology

Substances

  • Fatty Acids
  • Hypoglycemic Agents
  • Insulin
  • Palmitates
  • Ribonucleotides
  • Aminoimidazole Carboxamide
  • AMP-Activated Protein Kinases
  • AICA ribonucleotide