FIG. 1.

Antioxidant inhibits LPS-induced osteoclastogenesis via JNK signaling pathways. (A, E) Preosteoclasts were treated with 1 μg/ml LPS in the absence or presence of NAC (antioxidant, 20 mM) or SP600125 (JNK inhibitor, 20 μM). On day 4, cells were fixed and stained for TRAP. Cell morphology was examined by light microscopy, and TRAP-positive MNCs having more than three nuclei (arrows) were counted. (B–D, F, G) Preosteoclasts were serum starved for 12 h and stimulated with 1 μg/ml LPS in the absence or presence of NAC (20 mM) or SP600125 (20 μM). After 24 h, whole-cell extracts were harvested from cultured cells and subjected to SDS-PAGE and Western blot analysis to detect p-JNK, NFATc1, or c-Fos. Antibodies specific for JNK and β-actin were used to normalize the cell extracts. All values are the mean±SD of three independent experiments. *p<0.05, **p<0.01, and ***p<0.005; scale bar=200 μm. JNK, c-Jun N-terminal protein kinase; LPS, lipopolysaccharide; MNCs, multinucleated cells; NAC, N-acetyl-cysteine; NFATc1, nuclear factor of activated T-cells, cytoplasmic 1; SD, standard deviation; SDS-PAGE, sodium dodecyl sulfate–polyacrylamide gel electrophoresis; TRAP, tartrate-resistant acid phosphatase.