FIGURE 3.

Transcription from the PPARα gene is rapidly and effectively repressed by glucose in β-cells. A, INS-1E cells were preincubated in 5 mm glucose medium for 24 h and subsequently cultured at either 5 or 25 mm glucose for the indicated time periods. B, INS-1E cells were preincubated in 5 mm glucose medium for 24 h and subsequently cultured in 5 or 25 mm glucose medium with or without 10 μg/ml cycloheximide for 6 h. C, isolated rat pancreatic islets were preincubated in 3 mm glucose for 24 h before culture in either 3 or 25 mm glucose medium with or without 1 mm metformin (Met.). Expression levels of PPARα and GPDH were determined by quantitative PCR. The bars represent the means ± S.D. of three independent experiments. *, p < 0.05 versus 5 mm glucose ± cycloheximide (CHX); ¤, p < 0.01 versus 5 mm glucose and 25 mm glucose ± cycloheximide; ^, p < 0.05 versus 5 mm glucose ± cycloheximide and 25 mm glucose; #, p < 0.05 versus 5 mm glucose (one-way ANOVA).