Arachidonic Acid (AA) and Tetradecanoylphorbol Acetate (TPA) Exert Systemic Effects When Applied Topically in the Mouse

We studied the systemic actions of topically applied arachidonic acid (AA) and tetradecanoylphorbol acetate (TPA) in the mouse. AA or TPA-induced ear edema, increases in vascular permeability, eicosanoid levels, neutrophil and mononuclear influx were determined in both phlogogen-treated and contralateral vehicle-treated ear of each mouse and were compared with vehicle-treated ears from control mice. Edema and vascular permeability increases appeared only in AA- or TPA-applied ears. Moreover, in contralateral ears from AA-treated mice an increase in 6-keto-PGF₁ and LTB₄ was found. Only LTB₄ increased in the contralateral ear after TPA. Contralateral ears from AA- or TPA-treated mice also showed a significant increase in MPO levels. The increased levels of 6-keto-PGF₁ but not those of LTB₄ in contralateral ears were reduced by indomethacin applied simultaneously with the phlogogen. AA also increased plasma and serum levels of LTB₄, but not those of 6-keto-PGF₁. In contrast, TPA increased plasma and serum levels of 6-keto-PGF₁ and LTB₄. The results show that both AA and TPA applied topically exert systemic effects.