Dietary L-carnitine alters gene expression in skeletal muscle of piglets

Mol Nutr Food Res. 2011 Mar;55(3):419-29. doi: 10.1002/mnfr.201000293. Epub 2010 Oct 11.

Abstract

Scope: Carnitine improves protein accretion, muscle mass, and protein:fat accretion in piglets. The underlying mechanisms, however, are largely unknown.

Methods and results: To gain insight into mechanisms through which carnitine exerts these effects, we fed piglets either a control or a carnitine-supplemented diet, and analyzed the transcriptome in skeletal muscle. Carnitine concentrations in plasma and muscle were about four-fold higher in the carnitine group when compared to the control group. Transcript profiling revealed 211 genes to be differentially expressed in muscle by carnitine supplementation. The identified genes were mainly involved in molecular processes such as cytoskeletal protein binding, insulin-like growth factor (IGF) binding, transcription factor activity, and insulin receptor binding. Identified genes with the molecular function transcription factor activity encoded primarily transcription factors, most of which were down-regulated by carnitine, including pro-apoptotic transcription factors such as proto-oncogene c-fos, proto-oncogene c-jun and activating transcription factor 3. Furthermore, atrophy-related genes such as atrogin-1, MuRF1, and DRE1 were significantly down-regulated by carnitine. IGF signalling and insulin signalling were identified as significantly up-regulated regulatory pathways in the carnitine group.

Conclusion: Carnitine may have beneficial effects on skeletal muscle mass through stimulating the anabolic IGF-1 pathway and suppressing pro-apoptotic and atrophy-related genes, which are involved in apoptosis of muscle fibers and proteolysis of muscle proteins, respectively.

MeSH terms

  • Analysis of Variance
  • Animal Feed
  • Animal Nutritional Physiological Phenomena*
  • Animals
  • Carnitine / pharmacology*
  • Diet / veterinary*
  • Dietary Supplements
  • Down-Regulation
  • Energy Metabolism
  • Gene Expression Profiling
  • Genetic Association Studies
  • Insulin-Like Growth Factor I / metabolism
  • Male
  • Microarray Analysis
  • Muscle, Skeletal / drug effects*
  • Muscle, Skeletal / growth & development
  • Swine
  • Transcription Factor 3 / metabolism
  • Up-Regulation
  • Weight Gain

Substances

  • Transcription Factor 3
  • Insulin-Like Growth Factor I
  • Carnitine