Glucocorticoids: Lipolytic or Lipogenic?

The effects of glucocorticoids (GCs) on lipid metabolism are controversial with some studies indicating that GCs stimulate lipolysis, while others suggest lipogenesis. The purpose of this study was to clarify the role of GCs in lipolysis by utilizing a range of GC concentrations and to assess the long‐term effects of GCs on basal lipolytic rates. In study #1, both 3T3‐L1 were treated for 24h with increasing concentrations of GCs (0.01‐100 uM) and subsequently assayed for glycerol concentration as a marker of lipolysis. Lipolysis increased above control cells in a parabolic fashion to a maximum of 1.9±0.2 fold with 0.1 uM GC (P<0.01). In study #2, 3T3‐L1 were treated with varying GC doses for 24 hrs, then washed and resuspended in fresh GC‐free media. Glycerol was measured 1hr post GC removal. Basal lipolytic rates increased in a dose‐dependent and linear manner, with 100uM GC treatment resulting in a 4.6±0.47 fold increase in lipolysis. The responses in both studies were specifically related to GC treatment as co‐treatment with the GC receptor antagonist mifepristone abolished the effects. These results were confirmed in primary adipocytes (subcutaneous and epididymal). Based on these findings, we hypothesize that GCs can cause both in a lipolytic and anti‐lipolytic manner depending on the concentrations present and their duration of exposure.