Pharmacological characterisation of arthritis induced by Bothrops jararaca venom in rabbits: a positive cross talk between bradykinin, nitric oxide and prostaglandin E2.

BACKGROUND Our previous results showed that nitric oxide (NO) and bradykinin (BK) mediate the arthritis induced by Bothrops jararaca venom (BjV) in rabbits. In this study, we investigated the contribution of each receptor of BK as well as the inter-relationship between NO and eicosanoids in BjV-induced arthritis. METHODS The arthritis was induced in rabbits with 16 microg of BjV injected intra-articularly. Prostaglandin E2 (PGE2), thromboxane B2 (TxB2), leukotriene B4 (LTB4) (radioimmunoassay) and nitrite/nitrate concentrations (NO2/NO3) (Griess reaction) were evaluated in the synovial fluid 4 h later. The animals were prior treated with NO synthase inhibitor (L-NAME; 20 mg/kg/day for 14 days), the B2 antagonist of BK (HOE-140) and the B1 antagonist of BK (des-Arg9[Leu8]-bradykinin), both at a dose of 0.3mg/kg, 30 min prior to the venom injection. RESULTS Data show that L-NAME and HOE-140 treatment were equally able to reduce PGE2 and NO2/NO3 levels without interfering with TxB2 and LTB4 production. On the contrary, the B1 antagonist of BK inhibited TxB2 and LTB4 production, and did not alter PGE2 and NO metabolites levels in the inflamed joint. DISCUSSIONS The results presented clarify the contribution of the kinin system, mainly through the B2 receptor, to the local inflammatory response induced by BjV, as well as its positive interaction with PGE2 and NO production.