Evaluation of a screening system for obesogenic compounds: screening of endocrine disrupting compounds and evaluation of the PPAR dependency of the effect

PLoS One. 2013 Oct 14;8(10):e77481. doi: 10.1371/journal.pone.0077481. eCollection 2013.

Abstract

Recently the environmental obesogen hypothesis has been formulated, proposing a role for endocrine disrupting compounds (EDCs) in the development of obesity. To evaluate this hypothesis, a screening system for obesogenic compounds is urgently needed. In this study, we suggest a standardised protocol for obesogen screening based on the 3T3-L1 cell line, a well-characterised adipogenesis model, and direct fluorescent measurement using Nile red lipid staining technique. In a first phase, we characterised the assay using the acknowledged obesogens rosiglitazone and tributyltin. Based on the obtained dose-response curves for these model compounds, a lipid accumulation threshold value was calculated to ensure the biological relevance and reliability of statistically significant effects. This threshold based method was combined with the well described strictly standardized mean difference (SSMD) method for classification of non-, weak- or strong obesogenic compounds. In the next step, a range of EDCs, used in personal and household care products (parabens, musks, phthalates and alkylphenol compounds), were tested to further evaluate the obesogenicity screening assay for its discriminative power and sensitivity. Additionally, the peroxisome proliferator activated receptor γ (PPARγ) dependency of the positive compounds was evaluated using PPARγ activation and antagonist experiments. Our results showed the adipogenic potential of all tested parabens, several musks and phthalate compounds and bisphenol A (BPA). PPARγ activation was associated with adipogenesis for parabens, phthalates and BPA, however not required for obesogenic effects induced by Tonalide, indicating the role of other obesogenic mechanisms for this compound.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3-L1 Cells
  • Adipocytes / drug effects
  • Adipocytes / metabolism
  • Adipocytes / pathology
  • Animals
  • Cell Differentiation / drug effects
  • Endocrine Disruptors / adverse effects*
  • Endocrine Disruptors / analysis*
  • Insulin / pharmacology
  • Mice
  • Obesity / chemically induced*
  • Obesity / genetics
  • PPAR gamma / antagonists & inhibitors
  • PPAR gamma / genetics
  • PPAR gamma / metabolism*
  • Reference Standards
  • Staining and Labeling
  • Transcriptional Activation / drug effects
  • Transcriptional Activation / genetics

Substances

  • Endocrine Disruptors
  • Insulin
  • PPAR gamma

Grant support

This work was supported by a GOA project (Endocrine disrupting environmental chemicals: From accumulation to their role in the global “neuro-endocrine” epidemic of obesity and its metabolic consequences; FA020000/2/3565) of the University of Antwerp. APF acknowledges the ‘Institute for the promotion of innovation by science and technology’ in Flanders (Belgium) for financial support. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.