Abstract:
The 3T3-L1 murine adipocyte cell line remains one of the most widely used models to study the
mechanisms of obesity and related pathologies. Most studies investigate such mechanisms using mature
adipocytes that have been chemically induced to differentiate for 7 days in media containing 25 mM
glucose. However, the dysfunctional characteristics commonly observed in obesity including adipocyte
hypertrophy, increased expression of inflammatory markers, enhanced production of reactive oxygen
species (ROS), increased steroidogenic enzyme expression/activity and production of steroid hormones,
are not necessarily mimicked in these cells. The aim of this study was to provide an inexpensive model
which represents the well-known characteristics of obesity by manipulating the time of adipocyte differentiation and increasing the concentration of glucose in the cell media. Our results showed a glucoseand time-dependent increase in adipocyte hypertrophy, ROS production and gene expression of the proinflammatory cytokine interleukin-6 (IL-6), as well as a time-dependent increase in lipolysis and in the
gene expression of the chemokine monocyte chemoattractant protein 1 (MCP1). We also showed that
gene expression of the steroidogenic enzymes 11-beta-hydroxysteroid dehydrogenase type 1 (11bHSD1),
17bHSD type 7 and 12, as well as CYP19A1 (aromatase), were significantly higher in the hypertrophic
model relative to the control adipocytes differentiated using the conventional method. The increase in
11bHSD1 and 17bHSD12 expression was consistent with the enhanced conversion of cortisone and androstenedione to cortisol and testosterone, respectively. As these characteristics reflect those commonly
observed in obesity, hypertrophic 3T3-L1 adipocytes are an appropriate in vitro model to study mechanisms of adipocyte dysfunction in an era where the rise in obesity incidence is a global health concern,
and where access to adipose tissue from obese patients are limited.
