Abstract: BACKGROUND: Due to the particularity of the ear structure, the skin at the auricle injury usually has poor motion range and tissue regeneration ability, and it is difficult to heal. Therefore, how to accelerate the wound healing and obtain an ideal repair effect has always been a problem and research hotspot in the field of surgery.
OBJECTIVE: To explore the effects of Sanhuang gel on the wound healing, basic fibroblast growth factor and interleukin 17 levels of auricle skin defect in rabbits. 
METHODS: Sixty male New Zealand rabbits were randomly divided into six groups (n=10 per group). In group A, no treatment was given. In groups B-F, a circular skin defect area with the diameter of 1 cm was made in the auricle. In group B, the wound was injected with physiological saline. In group C, the wound was coated with asiaticoside cream ointment. In group D, the wound was coated with Sanhuang gel. In group E, the wound was injected with PI3K/AKT agonist 740 Y-P. In group F, the wound was coated with Sanhuang gel and injected with 740 Y-P. The treatment was performed twice a day, for 30 consecutive days. The wound healing of rabbit ear was observed and recorded, and the pathological morphology of ear tissue was detected by hematoxylin-eosin staining. The mRNA relative expression levels of basic fibroblast growth factor and interleukin 17 in rabbit ear tissue were detected by real-time PCR. The protein expression of PI3K/AKT pathway in rabbit ear tissue was detected by western blot assay. 
RESULTS AND CONCLUSION: (1) After treatment, the skin wound healing speed was accelerated. After 30 days of treatment, the wound healing rate of Sanhuang gel and PI3K/AKT agonist alone was higher than that of asiaticoside cream ointment, and the combined application of the two had the highest wound healing rate. (2) Hematoxylin-eosin staining results showed that the epidermis of group B was significantly thickened and blood vessels were dilated; and a large number of infiltrated inflammatory cells and fibrous tissue hyperplasia were seen. Compared with group B, the morphology of groups C, D, E, and F was significantly improved, and new capillaries and numerous proliferated fibroblasts and endothelial cells were seen. Among them, group F had the most obvious improvement. (3) RT-PCR detection showed that the relative expression of basic fibroblast growth factor mRNA decreased and the relative expression of interleukin 17 mRNA increased after auricular skin injury. After different treatments, the relative mRNA expression of the two factors was improved to varying degrees. The improvement effect of Sanhuang gel and PI3K/AKT agonist alone was stronger than that of asiaticoside cream ointment, and the improvement effect of their combination was strongest. (4) Western blot assay showed that the expression of PI3K, AKT, p-PI3K, and p-AKT proteins decreased after auricular skin injury. The expression levels of the four proteins increased to varying degrees after different treatments. The elevating effect of Sanhuang gel and PI3K/AKT agonist alone was stronger than that of asiaticoside cream ointment, and the elevating effect of their combination was strongest. (5) The results show that Sanhuang gel can promote the wound healing of auricular skin defects, and its mechanism may be associated with the activation of PI3K/AKT pathway.  

Key words: Sanhuang gel, PI3K/AKT pathway, auricular skin defect, wound healing, basic fibroblast growth factor, interleukin-17