Both Type 1 and Type 2 Corticoid Receptors Modulate Glucocorticoids Effects on Adipocyte Precursor Cells

ZUBIRIA G; GIORDANO A; PORTALES A; SPINEDI E; GIOVAMBATTISTA A

Boston

Congreso; ENDO MEETING 2016; 2016

American Endocrine Society

Glucocorticoids are known to be involved in several functions of adipose tissue (AT). We have previously shown that dexamethasone (DXM) impacts on adipocyte precursor cells (APCs) from abdominal AT by enhancing their adipogenic capacity and number, although the role of type 1 (mineralocorticoid receptor, MR) and type 2 (glucocorticoid receptor, GR) corticoids receptors in these processes is still unclear. We have now evaluated whether MR or/and GR activities are critical for these DXM effects. For this aim, stromal vascular fraction cells isolated from retroperitoneal AT (RPAT), aseptically dissected from adult male S-D rats, were cultured until they reached confluence. Then, we added DXM alone (0.25 µM, DXM) or in combination with a GR inhibitor (RU486 1µM, DXM-RU), or an MR inhibitor (Spironolactone 10µM, DXM-SP) or both (DXM-RU-SP) for 48 h (pre-treatment). Culture medium without DXM was used for control cells (CTR). The expression of a specific adipocyte competency marker (PPAR-γ2) and corticoid receptors (MR and GR) was quantified in APCs after pre-treatment (qPCR Real Time). Additionally, differentiation was induced using the conventional cocktail (DIM) and the mRNA levels of PPAR-γ2 and C/EBPα on differentiation day 4 (Dd4) were determined. The percentage of PPAR-γ positive cells was determined by immunofluorescence (IF) on the same day. Finally, intracellular lipid content (Oil-Red O) was measured on Dd 10. Our data showed an increase of PPAR-γ2 gene expression in DXM cells after pre-treatment (P<0.05) that was only reverted when both receptor activities were blocked (DXM-RU-SP, P<0.05 vs DXM). The expression of MR and GR did not change in any group. Differentiated cells pre-treated with DXM showed increased mRNA levels of C/EBPα on Dd4 (P<0.05 vs CTR), which was suppressed only by DXM-RU-SP co-culturing (P<0.05 vs DXM), but not by any of the inhibitors separately. No changes were found in PPAR-γ2 mRNA levels. Interestingly, the percentage of PPAR-γ positive cells was higher in DXM than in CTR cells (P<0.05), and this percentage decreased in DXM-RU-SP co-treated cells (P<0.05 vs DXM). Finally, differentiated APCs pre-treated with DXM showed high adipocyte differentiation, quantified by Oil Red-O on Dd10, which was reverted only in presence of both inhibitors simultaneously (P<0.05 vs DXM). We conclude that the effects of DXM pre-treatment on APCs adipogenic potential may be driven by both receptors, MR and GR, and that the inhibition of both receptors would be necessary for the complete abolishment of these effects. Our results strongly support that both type 1 and type 2 corticoid receptors are involved in the effects caused by DXM in APCs from RPAT. Further studies should be performed to clarify the relative contribution of each receptor to DXM effects.