The roles of ppar-delta and ppar-gamma in regulating the metabolic switch between oxidation and storage of fats in white adipose tissue. Mus musculus

Obesity is a major risk factor for the development of insulin resistance and type II diabetes. The nuclear receptors PPAR-delta and PPAR-gamma play a central role in regulating metabolism in adipose tissue, as well as being targets for the treatment of insulin resistance. The metabolic effects of PPAR-delta and PPAR-gamma activation have been examined both in vivo in white adipose tissue from ob/ob mice and in vitro in cultured 3T3-L1 adipocytes using a combined 1H NMR spectroscopy and mass spectrometry metabolomic methodology to understand the contrasting roles of these receptors. These steady state measurements were supplemented with 13C-stable isotope substrate labeling to assess fluxes, respirometry and transcriptomic microarray analysis. The metabolic effects of the two receptors were readily distinguished, with PPAR-gamma activation characterised by increased fat storage and fat synthesis/elongation, while activation of PPAR-delta caused increased fatty acid beta-oxidation, TCA cycle rate and oxidation of extracellular branch chain amino acids. Stimulated glycolysis and increased desaturation of fatty acids were the only common pathways. PPAR-delta has a role as an anti-obesity target as well as an anti-diabetic. Overall design: Total RNA obtained from cultured 3T3-L1 cells treated for 48 hours with either DMSO control, GW610742 PPARd agonist or GW347845 PPARg agonist and compared.