Figure 3.

Expression of cannabinoid receptor 1 (CB₁) (a) and cannabinoid receptor 2 (CB₂) (b) receptor protein in synovial tissue of patients with osteoarthritis (OA) (lanes 2 to 5) or rheumatoid arthritis (RA) (lanes 6 to 8) detected by Western blotting and quantified by densitometry. CHO-K1 cells recombinantly expressing either CB₁ or CB₂ receptor were used as a positive control (lane 1). Receptor expression was calculated as a percentage of expression of the internal control, β-actin. Data are presented as mean ± standard error of the mean of the expression of CB₁ and CB₂ protein in four OA and four RA patients, assessed in three separate experiments. Expression of CB₁ (c) and CB₂ (d) receptor RNA in fibroblast-like synovial cells derived from tissue of patients with OA or RA detected by 'touchdown' polymerase chain reaction. A human neuroblastoma cell line (SH-SY5Y) endogenously expressing CB₁ cannabinoid receptor and CHO-K1 cells recombinantly expressing CB₂ receptor were used as positive controls, respectively. bp, base pairs.