Fig. 5.

4-PBA inhibits lipid accumulation during all stages of differentiation. A: Effect of 4-PBA on Oil red O staining in differentiating 3T3-L1 cells. 3T3-L1 cells were treated with 10 mM 4-PBA at the onset of differentiation in the presence of MDI (days 0–2), during mid-stages after the MDI was removed (days 2–6), and during late stages after the majority of cells had differentiated (days 6–10). All cells were fixed and stained with Oil red O 10 days after commencing the experiment. As controls, cells were treated in the presence or absence of 4-PBA from days 0–10. B: Quantification of Oil red O staining in the absence or presence of 4-PBA at all stages of adipogenesis. Oil red O stain was quantified, and a significant reduction in lipid accumulation in all conditions was observed with 4-PBA treatment compared with day 10 untreated control (**P < 0.001; n = 3). The decline in lipid content was most dramatic in cells treated with 4-PBA during the later stages of adipogenesis: on days 2–6 or 6–10 (*P < 0.05 compared with days 0–2).