Fig. 6

The mRNA expression of matrix metalloproteinases and pro-inflammatory cytokines in the articular cartilage at 21 days after intra-articular injection of monoiodoacetate (MIA). Ovariectomized (OVX) rats were provided with a 45 % fat diet containing (1) 0.4 % curcumin, (2) 0.4 % tetrahydrocurcumin (THC), (3) 30 μg/kg body weight 17β-estradiol + 0.4 % dextrin (positive control), (4) 0.4 % dextrin (control), or (5) 0.4 % dextrin (normal control for osteoarthritis). At the beginning of the fifth week, an articular injection of monoiodoacetate into the right knee was performed on all OVX groups except the normal-control group and the assigned diets were provided for an additional 3 weeks. Rats in the normal-control group had an articular injection of saline in the right knee. The mRNA expressions of MMP3 and MMP13 involved in collage degradation (a) and cytokines (TNF-α, IL1β, and IL6) that result in inflammation (b) were measured by real-time PCR. Each bar and error bar represents the mean ± SD (n = 6). (a, b, c) The bars with different letters were significantly different among groups by Tukey’s test at P < 0.05