Figure 1.

Dextromethorphan (DXM) reduced tumor necrosis factor-alpha (TNF-α)-induced loss of collagen II (Col II). (A) Porcine chondrocytes in serum-free medium were co-treated with TNF-α (5 ng/mL) and various doses of DXM as indicated for 24 h. Total cell lysates were analyzed with a Western blot. (B) Similar to (A), chondrocytes were treated with 10 μM DXM after TNF-α (5 ng/mL) stimulation at the indicated time, and total TNF-α stimulation time were 24 h (all TNF-α + samples). The total cell lysates were analyzed by Western blots. (C) Cartilage explants were stimulated with TNF-α (5 ng/mL) and Oncostatin M (OSM) (10 ng/mL), and treated with 10 μM DXM for 10 days. The retained Col II in cartilage explants were analyzed by immunostaining (original magnification, ×200), and the staining intensity and stained areas were calculated. (D) Chondrocytes were treated with TNF-α (5 ng/mL) and various doses of DXM as indicated for 16 h. Cellular mRNA were isolated and analyzed by real-time RT-PCR. Data were shown as the representative data from at least three independent experiments of different donors. Values are the means ± S.E.M. and significance (* p < 0.05; ** p < 0.01; *** p < 0.001) was analyzed by one-way ANOVA or Student’s t-test. The symbol of plus (+) or minus (−) indicates presence or absence of treatment, respectively.