Fig. 1.

Adipogenic differentiation of 3T3-L1 cells. A) Bright-field microscopy images (10×) of 3T3-L1 preadipocytes (U, untreated) and subjected to adipogenic differentiation using four different formulations including 0.5 mM IBMX, 250 nM dexamethasone and variable concentrations of insulin and rosiglitazone. + I, 1 µg/ml insulin;++ I, 10 µg/ml insulin;+ R, 2 µM rosiglitazone;++ R, 4 µM rosiglitazone. Cells were fixed and lipid droplets stained with Oil red O at 5, 9, 15 and 20 days after induction. B) Same as in A, with 10 µg/ml insulin and 2 µM rosiglitazone, fixed and Oil red O stained at day 7 after induction. Magnification 4×, inset 40×. C) Fat quantification through absorbance of Oil red O at 510 nm recuperated from discoloration of 3T3-L1 stained cells untreated (U) and after 7 days of adipogenic induction (D). A, B and C) Data were similar in two other experiments. D) aP2 gene relative expression measured by qPCR at 7 days of differentiation of 3T3-L1 cells compared to untreated cells. Bars represent averaged mean data from three biological and technical replicates of qPCR.