Hepatic glucose intolerance precedes hepatic steatosis in the male aromatase knockout (ArKO) mouse

PLoS One. 2014 Feb 10;9(2):e87230. doi: 10.1371/journal.pone.0087230. eCollection 2014.

Abstract

Estrogens are known to play a role in modulating metabolic processes within the body. The Aromatase knockout (ArKO) mice have been shown to harbor factors of Metabolic syndrome with central adiposity, hyperinsulinemia and male-specific hepatic steatosis. To determine the effects of estrogen ablation and subsequent replacement in males on whole body glucose metabolism, three- and six-month-old male ArKO mice were subjected to whole body glucose, insulin and pyruvate tolerance tests and analyzed for ensuing metabolic changes in liver, adipose tissue, and skeletal muscle. Estrogen-deficient male ArKO mice showed increased gonadal adiposity which was significantly reduced upon 17β-estradiol (E2) treatment. Concurrently, elevated ArKO serum leptin levels were significantly reduced upon E2 treatment and lowered serum adiponectin levels were restored to wild type levels. Three-month-old male ArKO mice were hyperglycemic, and both glucose and pyruvate intolerant. These phenotypes continued through to 6 months of age, highlighting a loss of glycemic control. ArKO livers displayed changes in gluconeogenic enzyme expression, and in insulin signaling pathways upon E2 treatment. Liver triglycerides were increased in the ArKO males only after 6 months of age, which could be reversed by E2 treatment. No differences were observed in insulin-stimulated ex vivo muscle glucose uptake nor changes in ArKO adipose tissue and muscle insulin signaling pathways. Therefore, we conclude that male ArKO mice develop hepatic glucose intolerance by the age of 3 months which precedes the sex-specific development of hepatic steatosis. This can be reversed upon the administration of exogenous E2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adiponectin / blood
  • Adipose Tissue / drug effects
  • Adipose Tissue / pathology
  • Animals
  • Aromatase / deficiency*
  • Aromatase / metabolism*
  • Blood Glucose / metabolism
  • Body Weight / drug effects
  • Estrogens / pharmacology
  • Gluconeogenesis / drug effects
  • Gluconeogenesis / genetics
  • Glucose Intolerance / blood
  • Glucose Intolerance / enzymology*
  • Glucose Intolerance / pathology
  • Insulin / blood
  • Insulin Resistance
  • Leptin / blood
  • Liver / drug effects
  • Liver / metabolism*
  • Liver / pathology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Muscles / metabolism
  • Organ Size / drug effects
  • Phosphorylation / drug effects
  • Pyruvic Acid / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Real-Time Polymerase Chain Reaction
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • Triglycerides / metabolism

Substances

  • Adiponectin
  • Blood Glucose
  • Estrogens
  • Insulin
  • Leptin
  • RNA, Messenger
  • Triglycerides
  • Pyruvic Acid
  • Aromatase

Grants and funding

This research was supported by Australian National Health and Medical Research Council project grants ID 338510, 494813, and 628553 and program grant 441100. MLS was supported by Monash Postgraduate Scholarship; WCB was supported by a Fred P Archer Fellowship. The authors acknowledge the support of the Victorian Government through the Operational Infrastructure Scheme. SQT was supported by the Cancer Council of Victoria Postdoctoral Cancer Research Fellowship and PHI audit #13–33. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.