Pharmacological study of cantharidin-induced ear inflammation in mice

Cantharidin applied to the Swiss mouse ear induced a clearly observable inflammatory reaction after 6 hr, maximal after 24 hr, and persisting several days. Desonide and hydrocortisone strongly inhibited the acute (6 hr) and delayed (24 hr) phases after their local application, while, after oral treatment, a reduction in the acute edema was obtained only when using high doses. The cutaneous application of high doses of mepyramine, disodium cromoglycate, methysergide, and (at a quite lower level) cimetidine reduced the 6-hr inflammation. Phenylbutazone and acetylsalicylic acid showed little activity on the same phase after their cutaneous administration. All the nonsteroid compounds produced little or no effect on the 24-hr inflammation after their cutaneous application and were quite inactive on both phases after their systemic treatment. The cantharidin-induced inflammatory reaction in Swiss mouse seems thus to be characterized by two phases. The chronic delayed phase is an example of chronic inflammation without the involvement of immunological processes. Histamine and serotonin might be involved in the acute inflammation.