5.6.1. Xylene-Induced Ear Edema Model

According to the previous protocol [48], the adult male mice were randomly divided into control group, xylene group, positive drug group (indomethacin), DKK-SP1 groups (2, 1, 0.5 mg/kg). DKK-SP1 and indomethacin were diluted with normal saline into each dose, with 12 mice in each group. The DKK-SP1 groups were intravenously injected DKK-SP1 (2, 1, 0.5 mg/kg) and the positive drug group was established by intraperitoneal injection of indomethacin (10 mg/kg). The control group and xylene group were intravenously injected with normal saline. One hour after the administration, each mouse was smeared with 30 μL xylene on the right ear, and the left ear was used as a control. Thirty minutes after inflammation induction [49], the mice were euthanized and both ears were taken by a 6 mm diameter symmetrical hole. The weight of the left and right ears was measured to calculate the mouse ear swelling rate (%).

Ear swelling rate (%) = (the right ear weight − the left ear weight)/the left ear weight × 100%