β-estradiol (E) or relaxin (R) treatment causes loss of GAGs from specific fibrocartilages while progesterone (P) inhibits this effect. Temporomandibular joint (TMJ) discs, pubic symphysis, knee meniscus, and articular cartilage were retrieved from control and hormone-treated rabbits, and total GAG content was determined by dimethylmethylene blue assay and normalized to the total dry weight for each sample. Histograms of the mean (± standard deviation) GAG concentration in sham-operated controls (SC), ovariectomized normal controls (NC), and rabbits treated with E, R, ER, P, P + R (PR), and E + P + R (EPR) groups were plotted. Ovariectomy had minimal effect on total GAGs present in any of these four tissues. E, R, and ER produced a significant reduction of GAGs in TMJ disc (a) and pubic symphysis (b) relative to SC and NC groups. P alone contributed to the maintenance of GAGs in all these tissues or prevented E-, R-, or ER-mediated loss of GAGs from both TMJ disc and pubic symphysis. None of these hormone treatments caused a significant change of GAGs in knee articular cartilage (c) and meniscus (d). Data were collected from a minimum of six rabbits in each group. (* < 0.05; ** < 0.01; *** < 0.001; **** < 0.0001; a, versus SC; b, versus NC; c, versus P; d, versus PR; e, versus EPR.) ANOVA, analysis of variance; NS, not significant.
Hashem et al. Arthritis Research & Therapy 2006 8:R98 doi:10.1186/ar1978