Effect of clonidine on experimental brain edema in the rat.

Several experimental brain edema models are currently available for drug evaluation. Brain edemas are essentially vasogenic and/or cytotoxic, and eicosanoids are involved in the development of these edemas. Thus, a new model developed in our laboratory, which was obtained by phospholipase A2 intracerebral injection was used to study the antiinflammatory effect of clonidine. The copper wire edema model was chosen as reference. Edemas were evaluated by determining the swelling and Na+ and K+ tissue concentrations of each hemisphere. Drugs were administered intraperitoneally. Dexamethasone was the only drug to inhibit copper wire-induced edema, whereas indomethacin and clonidine as well as dexamethasone exhibited marked antiedematous activity in our model. The effect of clonidine, which could be inhibited by prior administration of yohimbine, suggests that central alpha 2-adrenergic stimulation is involved in reducing experimental brain edema.