| Objective: To investigate the mechanism of Protective spray against rays for medical use in promoting the ulcer healing on the base of established animal model ofβradiationⅡdegree skin injury.Methods: Fifty-five female SD rats were divided into 3 groups. The model of acute radiation-induced skin ulcers in rats was replicated with 45 Gy electron acceleratorβ-ray to the skin.Treatment group,n=23, was applicated of Protective spray against rays for medical use after the skin ulcer appear;Control group,n=23, was applicated of placebo after the skin ulcer appear;Normal rats,were served as normal control group,n=9. The wound healing time were observed and the parts of the ulcer tissue were taken respectively in the 0, 1, 2, 3, 4, 5 week after the ulcer had formed. The expression of VEGF, SOD activity, MDA content,cell ultrastructure in these tissue and SOD activity, MDA content in the blood were respectively assessed by histochemistry,biochemical detection and electron microscopy.Results:①R ats after radiation,The local skin radiated byβ-ray of began to shed in 2 weeks, irritation and blisters had appeared in 3 weeks, ulcers had formed in 4 weeks and gradually increased in size, the wound was no longer increasing in five weeks. The wound healing time of the Treatment group was 41.7±3.7 days,it was significantly shorter than the control group (61.3±4.5 days).②The quality of fibroblasts, epithelial cells, vascular endothelial cells in treatment group was higher than the control group which were observed by light microscopy and electron microscopy,and the damagement of the ultrastructure in treatment group was less than the control group.③1, 2, 3, 4, 5 weeks after treatment,the VEGF integral absorbance (IA) was significantly higher than control group. There is statistical significance between the two groups(P<0.05).④The SOD activity in blood and skin tissue of the treatment group was significantly higher in 1, 2, 3, 4, 5 weeks after treatment, while the MDA levels were significantly lower than the control group, and both of the differences are statistically significance (P <0.05).Conclusion:①The animal model ofβradiation skin injury ,produced by the linear accelerator, is easy to establish and the dosage is accurate.②The exernal application of Protective spray against rays for medical use can promote healing of radiation skin injury in rats and shorten the healing time.③The mechanism is that increased SOD activite in skin and blood, can reduce free radical level of skin and blood,ease the hurt to fibriblast,epithelium,vascular endothelial cell, , increase the expression of VEGF, delay apoptosis, thus be advantageous to the healing of ulcer.
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