The action of anti-inflammatory agents in healthy temporomandibular joint synovial tissues is sex-dependent

This study evaluated the effects of dexamethasone, parecoxib, and glucosamine on cartilage thickness and cytokine levels in the temporomandibular joint (TMJ). Forty-eight rats (24 female, 24 male) were assigned to four treatments administered once daily for 7 days: control (saline intramuscularly), parecoxib (0.3 mg/kg intramuscularly), dexamethasone (0.1 mg/kg intramuscularly), and glucosamine (80 mg/kg orally). The thickness of TMJ cartilage and levels of four cytokines were measured. Median cartilage thickness was higher in males than in females in the control (253.2 vs. 240.4 μm, P = 0.0036), parecoxib (227.3 vs. 192.1 μm, P < 0.0001), and dexamethasone (227.1 vs. 170.5 μm, P = 0.017) groups, but was lower in males in the glucosamine group (214.5 vs. 239.6 μm, P = 0.0001). IL-1β was not detected. Median IL-1α levels differed between males and females in the parecoxib group (0.08 vs. 0.04 ng/ml, P = 0.0055), but not in the control (0.07 vs. 0.06 ng/ml), dexamethasone (0.06 vs. 0.04 ng/ml), or glucosamine (0.08 ng/ml vs. 0.06 ng/ml) groups (all P > 0.05). Only dexamethasone induced lower IL-6 levels in males than in females (median 4.6 vs. 2.1 ng/ml, P = 0.0044). Median TNF-α levels did not differ between males and females in the control (0.07 vs. 0.05 ng/ml) or parecoxib (0.07 vs. 0.05 ng/ml) groups (both P > 0.05), but dexamethasone (0.09 vs. 0.05 ng/ml, P = 0.0002) and glucosamine (0.09 vs. 0.07 ng/ml, P = 0.0259) induced higher TNF-α levels in females. Thus, the effects of the three treatments on the levels of cytokines and thickness of condylar cartilage were sex-dependent.