The Expression Of Apoptosis-related Genes In Acute β-irradiated Skin Injury In Rats

Objective: To investigate the dynamic expression of apoptosis-related genes Bcl-2,Bax and P53 in acute radiation-induced skin ulcers, and to explore the underlying mechanism involved in retarded healing of the ulcer.Methods: Fifty-four 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(radiation group, R, n=24); The model of second deep degree scald in rats was established by electrical scald instrument with constant temperature, 80℃, 8s and 25㎜were regarded as common traumatogenic factors respectively(burn group, B, n=24); and 6 normal rats were served as normal control group(normal control group, N, n=6). From different periods skin wounds, the expression of Bcl-2,Bax and P53 were respectively assessed by means of immunohistochemical technique and apoptosis was observed by transmission electron microscope and TUNEL assay.Results:①The local skin in the radiation group radiated byβ-ray 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 local skin in the radiation group formed second deep degree scald.②The result of the TUNEL stain manifested that the integral absorbance (IA) in the radiation group was much higher than control group. There is statistical significance between the two groups(P<0.05).③0, 1, 2, 3 weeks after wound emerging, the Bax and Bcl-2 integral absorbance (IA) was much higher than control group. There is statistical significance between the two groups(P<0.05).④The expression of Bax protein increased evidently with the increment of apoptosis, and it showed a good correlation with apoptosis in the process of wound healing. The expression of Bcl-2 protein decreased obviously as the apoptosis reached the beak, and it showed an ascending tendency up to normal level when the apoptosis decreased distinctively.Conclusions:①It was shown that apoptosis manifested three typical characteristics, namely early occurrence, high frequency and delayed disappearance after radiation, which might explain the delayed wound healing caused byβradiation.②Bcl-2,Bax and P53 genes may play an important role in the regulation of apoptosis and delayed wound healing of acuteβradiation skin injury.