Epinephrine and AICAR-induced PGC-1α mRNA expression is intact in skeletal muscle from rats fed a high-fat diet

Am J Physiol Cell Physiol. 2012 Jun 15;302(12):C1772-9. doi: 10.1152/ajpcell.00410.2011. Epub 2012 Apr 11.

Abstract

Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a master regulator of mitochondrial biogenesis and is controlled, at least in part, through AMP-activated protein kinase and p38-dependent pathways. There is evidence demonstrating that activation of these kinases and induction of PGC-1α in skeletal muscle are regulated by catecholamines. The purpose of the present study was to determine if consumption of a high-fat diet (HFD) impairs epinephrine and 5-aminoimidazole-4-carboxamide-1β-d-ribofuranoside (AICAR) signaling and induction of PGC-1α in rat skeletal muscle. Male Wistar rats were fed chow or a HFD for 6 wk and then given a weight-adjusted bolus injection of epinephrine (20, 10, or 5 μg/100 g body wt sc) or saline, and triceps muscles were harvested 30 min (signaling) or 2 and 4 h (gene expression) postinjection. Despite blunted increases in p38 phosphorylation, the ability of epinephrine to induce PGC-1α was intact in skeletal muscle from HFD-fed rats and was associated with normal increases in activation of PKA and phosphorylation of cAMP response element-binding protein, reputed mediators of PGC-1α expression. The attenuated epinephrine-mediated increase in p38 phosphorylation was independent of increases in MAPK phosphatase 1. At 2 h following AICAR treatment (0.5 g/kg body wt sc), AMP-activated protein kinase and acetyl-CoA carboxylase phosphorylation were similar in skeletal muscle from chow- and HFD-fed rats. Surprisingly, AICAR-induced increases in PGC-1α mRNA levels were greater in skeletal muscle from HFD-fed rats. Our results demonstrate that the ability of epinephrine and AICAR to induce PGC-1α remains intact in skeletal muscle from HFD-fed rats. These results question the existence of reduced β-adrenergic responsiveness in diet-induced obesity and demonstrate that increases in p38 phosphorylation are not required for induction of PGC-1α in muscle from obese rats.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / metabolism
  • Acetyl-CoA Carboxylase / metabolism
  • Adrenergic Agonists / pharmacology*
  • Aminoimidazole Carboxamide / analogs & derivatives*
  • Aminoimidazole Carboxamide / pharmacology
  • Animals
  • CREB-Binding Protein / metabolism
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Diet, High-Fat*
  • Dual Specificity Phosphatase 1 / metabolism
  • Epinephrine / pharmacology*
  • Male
  • Mitochondria, Muscle / drug effects
  • Mitochondria, Muscle / metabolism
  • Muscle, Skeletal / drug effects*
  • Muscle, Skeletal / metabolism
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
  • Phosphorylation
  • RNA, Messenger / metabolism*
  • RNA-Binding Proteins / genetics*
  • Rats
  • Rats, Wistar
  • Ribonucleotides / pharmacology*
  • Signal Transduction / drug effects
  • Time Factors
  • Transcription Factors / genetics*
  • Up-Regulation
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Adrenergic Agonists
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
  • Ppargc1a protein, rat
  • RNA, Messenger
  • RNA-Binding Proteins
  • Ribonucleotides
  • Transcription Factors
  • Aminoimidazole Carboxamide
  • CREB-Binding Protein
  • Crebbp protein, rat
  • Cyclic AMP-Dependent Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • AMP-Activated Protein Kinases
  • Dual Specificity Phosphatase 1
  • Acetyl-CoA Carboxylase
  • AICA ribonucleotide
  • Epinephrine