Effects of Estrogens on Adipokines and Glucose Homeostasis in Female Aromatase Knockout Mice

PLoS One. 2015 Aug 28;10(8):e0136143. doi: 10.1371/journal.pone.0136143. eCollection 2015.

Abstract

The maintenance of glucose homeostasis within the body is crucial for constant and precise performance of energy balance and is sustained by a number of peripheral organs. Estrogens are known to play a role in the maintenance of glucose homeostasis. Aromatase knockout (ArKO) mice are estrogen-deficient and display symptoms of dysregulated glucose metabolism. We aim to investigate the effects of estrogen ablation and exogenous estrogen administration on glucose homeostasis regulation. Six month-old female wildtype, ArKO, and 17β-estradiol (E2) treated ArKO mice were subjected to whole body tolerance tests, serum examination of estrogen, glucose and insulin, ex-vivo muscle glucose uptake, and insulin signaling pathway analyses. Female ArKO mice display increased body weight, gonadal (omental) adiposity, hyperinsulinemia, and liver triglycerides, which were ameliorated upon estrogen treatment. Tolerance tests revealed that estrogen-deficient ArKO mice were pyruvate intolerant hence reflecting dysregulated hepatic gluconeogenesis. Analyses of skeletal muscle, liver, and adipose tissues supported a hepatic-based glucose dysregulation, with a down-regulation of Akt phosphorylation (a key insulin signaling pathway molecule) in the ArKO liver, which was improved with E2 treatment. Concurrently, estrogen treatment lowered ArKO serum leptin and adiponectin levels and increased inflammatory adipokines such as tumour necrosis factor alpha (TNFα) and interleukin 6 (IL6). Furthermore, estrogen deficiency resulted in the infiltration of CD45 macrophages into gonadal adipose tissues, which cannot be reversed by E2 treatment. This study describes the effects of estrogens on glucose homeostasis in female ArKO mice and highlights a primary phenotype of hepatic glucose dysregulation and a parallel estrogen modified adipokine profile.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipokines / blood*
  • Adipose Tissue / metabolism
  • Animals
  • Aromatase / genetics*
  • Estradiol / blood*
  • Estradiol / pharmacology
  • Estrogens / blood*
  • Estrogens / pharmacology
  • Female
  • Gluconeogenesis*
  • Glucose / metabolism*
  • Homeostasis / drug effects*
  • Interleukin-6 / blood
  • Leptin / blood
  • Liver / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Muscle, Skeletal / metabolism
  • Triglycerides / metabolism
  • Tumor Necrosis Factor-alpha / blood

Substances

  • Adipokines
  • Estrogens
  • Interleukin-6
  • Leptin
  • Triglycerides
  • Tumor Necrosis Factor-alpha
  • Estradiol
  • Aromatase
  • Glucose

Grants and funding

This research was supported by Australian National Health and Medical Research Council project grants ID 338510, 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. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.