3.8. Animals and Induction of a Xylene-Induced Ear Edema Model

Detail procedures were described in a previous study [47]. In brief, six-week-old male ICR mice were purchased from OrientBio (Kwangju, Korea) and randomly divided into 4 groups (n = 9 mice per group): PBS intraperitoneally injected and administered mice (Intact control), PBS intraperitoneally injected and xylene-administered mice (Xylene control), dexamethasone intraperitoneally injected and xylene-administered mice, and RAC orally administered and xylene-administered mice. Before 30 min of topical application of PBS or xylene on the anterior surface of the right ear for 2 h, the mice were administered PBS, 15 mg/kg dexamethasone intraperitoneally and 100 mg/kg RAC orally. After the topical application of 0.03 mL of PBS and xylene on the anterior surface of the right ear, the mice were sacrificed, and changes in ear weight and histopathology were measured. For histological analysis, mouse ears were fixed in 10% formalin, embedded in paraffin, sectioned and stained with hematoxylin and eosin (H&E) following the general procedure. The experimental protocols were approved by the Institutional Animal Care and Use Committee of Korea Research Institute of Bioscience and Biotechnology (permission number KRIBB-AEC-17059). All mice were treated according to the Guide for the Care and Use of Laboratory Animals published by the US National Institutes of Health.