Effects of valeryl salicylate, a COX-1 inhibitor, on models of acute inflammation in mice

Abstract

The effect of valeryl salicylate (VS), an inhibitor of cyclooxygenase-1 (COX-1), was evaluated in arachidonic acid or croton oil-induced ear oedema and carrageenan-induced paw oedema in mice. Ear oedema was induced by topical administration of arachidonic acid (2 mg per ear; 20 μl) or croton oil (1 mg per ear; 20 μl) to the inner surface of the left ear and the change in the ear’s thickness was measured with a precision micrometer (Fisher, USA). VS significantly inhibited the arachidonic acid ear oedema after l h at doses of 1.5–45 μg per ear; however, only at the dose of 45 μg per ear was it able to significantly reduce the croton oil-induced oedema at 6 h. Paw oedema was induced by the injection of 25 μl of 1% carrageenan into the plantar aponeurosis of the right hind paw. The oedema was evaluated at 0.5, 1, 2, 4, 24, 48 and 72 h. Previously in our experiments, we observed two peaks in paw oedema formation: one at 2 h, in the early phase (0–4 h), and the other, occurring at 48 h after carrageenan injection, in the late phase (24–72 h). The pre-treatment with VS significantly reduced the paw oedema at 2 h, the same effect observed with celecoxib and indomethacin treatments. At 24 h, VS did not inhibit oedema but significantly increased it mainly at 48 h after carrageenan injection. These results showed that VS was pharmacologically active in these models and suggest that COX-1 may participate in the early and late phases of inflammation in the models studied.