Unsuppressed lipolysis in adipocytes is linked with enhanced gluconeogenesis and altered bile acid physiology in Insr(P1195L/+) mice fed high-fat-diet

Sci Rep. 2015 Nov 30:5:17565. doi: 10.1038/srep17565.

Abstract

High-fat diet (HFD) triggers insulin resistance and diabetes mellitus, but their link remains unclear. Characterization of overt hyperglycemia in insulin receptor mutant (Insr(P1195L/+)) mice exposed to HFD (Insr(P1195L/+)/HFD mice) revealed increased glucose-6-phosphatase (G6pc) expression in liver and increased gluconeogenesis from glycerol. Lipolysis in white adipose tissues (WAT) and lipolysis-induced blood glucose rise were increased in Insr(P1195L/+)/HFD mice, while wild-type WAT transplantation ameliorated the hyperglycemia and the increased G6pc expression. We found that the expressions of genes involved in bile acid (BA) metabolism were altered in Insr(P1195L/+)/HFD liver. Among these, the expression of Cyp7a1, a BA synthesis enzyme, was insulin-dependent and was markedly decreased in Insr(P1195L/+)/HFD liver. Reduced Cyp7a1 expression in Insr(P1195L/+)/HFD liver was rescued by WAT transplantation, and the expression of Cyp7a1 was suppressed by glycerol administration in wild-type liver. These findings suggest that unsuppressed lipolysis in adipocytes elicited by HFD feeding is linked with enhanced gluconeogenesis from glycerol and with alterations in BA physiology in Insr(P1195L/+)/HFD liver.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipocytes / metabolism*
  • Adipose Tissue, Brown / metabolism
  • Adipose Tissue, White / metabolism
  • Adipose Tissue, White / transplantation
  • Animals
  • Bile Acids and Salts / metabolism*
  • Blood Glucose
  • Body Weight
  • Diet, High-Fat*
  • Disease Models, Animal
  • Energy Metabolism
  • Fats / metabolism
  • Genotype
  • Gluconeogenesis*
  • Glycerol / metabolism
  • Hyperglycemia / genetics
  • Hyperglycemia / metabolism
  • Insulin / metabolism
  • Insulin Resistance
  • Lipolysis*
  • Liver / metabolism
  • Mice
  • Mice, Transgenic
  • Models, Biological
  • Mutation
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism
  • Pyruvic Acid / metabolism
  • Receptor, Insulin / genetics*

Substances

  • Bile Acids and Salts
  • Blood Glucose
  • Fats
  • Insulin
  • Pyruvic Acid
  • Receptor, Insulin
  • Proto-Oncogene Proteins c-akt
  • Glycerol