Fig. 6

Effect of NE or β-AR blockers on IL-1β-activated signaling pathways in human chondrocytes. Chondrocytes were pretreated with (A) β-AR blockers (P, A, B, and N; 1.0 ng/ml) or (B) NE (1.0 ng/ml) 2 h before stimulation with IL-1β (1 ng/ml) for 15, 30, and 60 min. Phosphorylation of Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), p38 MAPK, and Iκ-Bα was analyzed by Western blot. Western blots shown are representative of four independent experiments. β-actin was used as a loading control. Propranolol (P), atenolol (A), nebivolol (B), and nadolol (N). (C-D)The relative phosphorylation of JNK, ERK, p38, and Iκ-Bα. Protein band density was measured using Image J and normalized to the respective unphosphorylated protein, but β-actin in case of p-Iκ-Bα. Data represent the mean ± SD of data from four different donors. *P < 0.05, **P < 0.01, and ***P < 0.001 vs. IL-1β-treated cells by (C) Kruskal-Wallis test followed by Dunn’s multiple comparison test or (D) Mann-Whitney test