Figure 2.

The effect of limonin on IL-1β-stimulated NO, PGE2, TNF-α, and IL-6 synthesis in chondrocytes. The pretreatment of chondrocytes with limonin at different concentrations (0, 15, 30, and 60 μM) for 24 hrs. (a) In the culture medium, the levels of NO were evaluated by Griess reaction. (b–d) The concentrations of PGE2, TNF-α, and IL-6 were evaluated by ELISAs. (e–h) The levels of mRNA expression of INOS, COX-2, TNF-α, and IL-6 were evaluated by RT-PCR. (i-k) The protein expression of COX-2 and INOS was evaluated by western blot assay. The results are expressed as the averages ± S.D. Significant differences among various groups are represented as ^∗p < 0.05, ^∗∗p < 0.01; n = 3.