Direct measurement of superoxide-dependent chemiluminescence from rat skin following UV-dependent fluoroquinolone-induced dermatitis

Fluoroquinolones are widely used for the treatment of bacterial infection. However, some members of the group cause UV-dependent dermatitis. Therefore, animal models are required to screen and predict if a derivative is likely to cause photodermatitis. Under anaesthesia, the hair on the dorsal side of rats was shaved, then a fluoroquinolone derivative, Y-26611 or ofloxacin was administered subcutaneously (SC) followed by irradiation of a 3 cm diameter circular area of the skin with UV-B(ultraviolet-B) for 45 min. Peak photodermatitis was observed 24 h after irradiation in Y-26611-treated skin. Leucocyte infiltration into the skin, mostly polymorphonuclear leucocytes, was verified by histological techniques. O2·--radical generated by activated leucocytes was detected directly from the skin by SC application of a sensitive O2·−-dependent luminescence reagent, MCLA. O2·−-dependent photon emission (chemiluminescence) from the skin was amplified by phorbol myristate acetate and was markedly suppressed by superoxide dismutase. This is the first report of direct detection of chemiluminescence from the skin of a living animal.