Mouse paw edema. A new model for inflammation?

1. Injection of carrageenan into the mouse paw produced a biphasic edema. During the first phase, which developed up to 24 h, edema was of low intensity and unrelated to the dose of carrageenan given. During the second phase, after 24 h, edema was more pronounced, presented a clear dose-response relationship and peaked at 72 h after injection. 2. Histological analysis of the subplantar area 4 h after carrageenan injection revealed a diffuse cellular infiltrate with predominance of polymorphonuclear neutrophils. Between 48 and 72 h, an intense accumulation of macrophages, eosinophils and lymphocytes was observed, together with a great increase in the number of circulating leukocytes and platelets. 3. Pretreatment with the anti-inflammatory drugs indomethacin and dexamethasone reduced both phases of edema in a dose-dependent fashion. 4. The present study shows that carrageenan-induced mouse paw edema constitutes a new and interesting model for the study of the mediators of inflammation and for the screening of new anti-inflammatory drugs.