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Nitric oxide synthase inhibitor influences prostaglandin and interleukin-1 production in experimental arthritic
S B de Mello1, G S Novaes, I M Laurindo
1Rheumatology Division, School of Medicine, University of São Paulo, Brazil.
Objective:
To assess involvement of nitric oxide (NO) in the increase in eicosanoid and interleukin- 1 (IL-1) levels in the synovial fluid during antigen-induced arthritis (AIA) in rabbits treated with a competitive inhibitor of NO synthesis.
Subjects:
Thirteen New Zealand White rabbits were sensitized with 5 mg of methylated bovine serum albumin (mBSA). Arthritis was induced in the knee joint by injecting 0.5 ml of a sterile solution of mBSA (2 mg/ml) into the intra-articular cavity.
Treatment:
Prior to the induction of arthritis, the animals received N-Omega-Nitro-L-Arginine Methyl Ester (LNAME) or N-Omega-Nitro-D-Arginine Methyl Ester (DNAME) for 2 weeks, both at a dose of 20 mg/kg/day mixed with drinking water.
Methods:
Leukocyte efflux (total and differential white cell count), vascular permeability (Evans's blue method), synovial PMN cell infiltrate, and total nitrite (NO2.)/nitrate (NO3.) (HPLC), PGE2, TxB2, LTB4 (radioimmunoassay), and IL-1 beta (ELISA) levels were quantified in the synovial fluid.
Results:
LNAME but not DNAME significantly suppressed leukocyte efflux and protein leakage into the articular cavity as well as synovial PMN cell infiltrate. Total NO2./NO3., PGE2 and IL-1 beta levels were significantly reduced in the synovial fluid of LNAME treated animals. TxB2 and LTB4 were not affected by LNAME treatment.
Conclusion:
These data clearly show NO involvement in the IL-1-induced PGE2 production in the synovial fluid of antigen-induced arthritis in rabbits.