Fig. 1Expression of caspase 3 and cleaved caspase 3 in INS-1 cell. (A) Caspase 3 and cleaved caspase 3 were measured by Western blot analysis. (B, C) Densitometric analyses of Western blot are reported as means ± SD of the three different experiments. C, control; IHG, intermittent high glucose; SHG, sustained high glucose. aP < 0.05 vs. control, bP < 0.05 vs. IHG.
Fig. 2Hoechst 33347 staining. (A) After INS-1 cell were incubated under control, IHG and SHG, they were stained with Hoechst 33347 to detect apoptosis morphologically. The red arrows represent cells with DNA condensation. (B) The numbers of cells with broken DNA per 300 cells in three different fields in each condition of one experiment were counted and repeated in three different experiments. The mean percentages of positive staining under control, IHG and SHG were presented by histogram. C, control; IHG, intermittent high glucose; SHG, sustained high glucose. aP < 0.05 vs. control, bP < 0.05 vs. IHG.
Fig. 3Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). (A) TUNEL stainings under control, IHG and SHG were analyzed by fluorescent in situ hybridization (FISH). (B) The percentage of TUNEL positive apoptotic cells / area was presented in histogram. C, control; IHG, intermittent high glucose; SHG, sustained high glucose. aP < 0.05 vs. control, bP < 0.05 vs. IHG.
Fig. 4Insulin secretion from INS-1 cells in response to glucose (5 and 25 mM) after incubated for 5 days in control, IHG and SHG. Data are means ± SD of three separate experiments. C, control; IHG, intermittent high glucose; SHG, sustained high glucose. aP < 0.05 vs. control of 25 mM glucose, bP < 0.05 vs. IHG of 25 mM glucose.
Fig. 5The changes of the expression of MnSOD and Bcl-2 in response to control, IHG and SHG. (A) Expression of Mn-SOD and Bcl-2 were evaluated by Western blot analysis. A representative experiment of three is shown. (B, C) Densitometric analyses of western blot are reported as means ± SD of the three different experiments. C, control; IHG, intermittent high glucose; SHG, sustained high glucose. aP < 0.05 vs. control, bP < 0.05 vs. IHG.