Pharmacological Characterization of Mouse Hind Paw Edema Induced by Parachartergus fraternus Venom.

Stings from the wasp Parachartergus fraternus occur throughout Latin America, and edema followed by pain is the main symptom presented by victims. This often limited inflammatory event has not been characterized for this species. In this work, we identified the mechanisms and possible mediators involved in this response. P. fraternus venom (100, 200, and 400 µg/kg) was injected into the hind paws of mice, and edema was evaluated at intervals of 10 min for up to 60 min and at 120, 240, and 1440 min using a digital plethysmometer. The peak of edema was observed at 10 min with a dose of 200 µg/kg. A reduction in edema was observed with indomethacin (58.1%), celecoxib (44.5%), MK886 (30.8%), and dexamethasone (53.2%). Loratadine, cimetidine, and cyproheptadine treatment reduced the edema by 54.2%, 63.9%, and 84.4%, respectively, compared with the control. Captopril and L-NAME inhibited 42.5% and 69.8%, respectively, of the edema. These results showed that the edema induced in mice by P. fraternus venom occurs early and is mediated by arachidonic acid derivatives, vasoactive amines, and nitric oxide. Together, these mediators amplify the inflammatory process, with emphasis on histamine and serotonin in triggering the edematogenic response, being more effective the use of cyproheptadine in the therapeutic approach.