Fig. 4.

Resveratrol inhibits Cd-induced neuronal cell death by blocking JNK and extracellular signal-regulated kinases 1/2 (Erk1/2) pathways. PC12 cells and primary neurons were pre-treated with resveratrol (Res, 0–100 μM for 1 h, or with/without Res (100 μM in the presence or absence of SP600125 (20 μM or U0126 (5 μM for 1 h, and then exposed to Cd (10 and/or 20 μM for 4 h (for western blotting) or 24 h (for 4′,6-diamidino-2-phenylindole, DAPI staining). (a–c) Indicated cell lysates were subjected to western blot analysis using indicated antibodies, showing that resveratrol partially inhibited Cd-induced phosphorylation of JNK/c-Jun, Erk1/2 and p38 in the cells (a and b), and inhibitors of Erk1/2 (U0126) and JNK (SP600125) strengthened the inhibitory activity of resveratrol (c). The blots were probed for β-tubulin as a loading control. Similar results were observed in at least three independent experiments (a and c), and blots for p-JNK, p-c-Jun, p-Erk1/2, p-p38 were semi-quantified (b). (d) The percentages of apoptotic cells with fragmented nuclei were quantified by DAPI staining, showing that pharmacological inhibition of JNK and Erk1/2 enhanced resveratrol prevention of Cd-induced neuronal cell death. Results are presented as mean ± SE, n = 5. Using one-way or two-way anova, ^ap < 0.05, difference with control group; ^bp < 0.05, difference with 10 μM Cd group; ^cp < 0.05, difference with 20 μM Cd group; ^dp < 0.05, difference with Cd/SP600125 group, Cd/U0126 group or Cd/Res group.