Figure 3

Valproate pretreatment prevents palmitate-induced apoptosis and ER distension. INS-1 cells were pretreated with or without 1 mM VPA for 48 h before challenged with 0.25 mM PA. ( A ) After the treatments for 24 h, apoptosis was assessed by staining cells with Hoechst 33342/PI (a - c), meanwhile the morphology of INS-1 cells was also captured (d - f). Apoptosis was characterized by nucleus condensed or fragmented (red arrows) that intensely stained with Hoechst 33342 (blue fluorescence). In each case five to seven microscopic fields were photographed randomly. Scale bars: a-f = 400 × magnification. (B) After the treatments for 24 h or 48 h, the cells were stained with Annexin V and PI, and the percentage of apoptosis was detected by flow cytometry. Data are mean ± SD of three independent experiments. **P < 0.01; ^§P < 0.001. (C) After the treatments for 24 h, (a - c) apoptosis and (d - f) morphology of ER were visualized by electron microscopy. The presence of marked chromatin condensation was considered to be a sign of apoptosis. ER distension is marked with red arrows. Scale bars: a-c = 2 μm; d-f = 1 μm.