N-Acetyl-Serotonin Protects HepG2 Cells from Oxidative Stress Injury Induced by Hydrogen Peroxide

Figure 3

NAS inhibits H₂O₂-induced HepG2 cells apoptosis. (A) Apoptotic cells detected by flow cytometry after annexin V and PI double-staining. (B) (a, b, c) Morphologic changes in nuclei observed with Hoechst 33342 staining under fluorescence microscopy. (C) (d, e, f) Apoptotic cells detected by TUNEL staining. (a, d) Untreated group; (b, e) H₂O₂ group, HepG2 cells incubated with 200 μM H₂O₂ for 6 hours; (c, f) H₂O₂ + NAS group, 10 μM NAS was administered before subjecting to H₂O₂. Note that untreated group cells appeared to have a normal shape with a round intact nuclei; H₂O₂-treated cells showed reduced nuclear size, strong fluorescent spot, and pyknotic nuclei, indicating apoptotic nuclei; the strong fluorescent spots were almost completely abrogated by pretreatment with NAS. The arrows indicate apoptotic cells. Original magnification ×400.