不同剂量紫外线照射对大鼠视网膜醛脱氢酶的活性及表达量的影响

Effect of different doses of ultraviolet radiation on the activity and expression of aldehyde dehydrogenase in retina of rats

目的探究紫外线照射总剂量不变、不同单次照射剂量对大鼠视网膜醛脱氢酶(ALDH)活性及表达量的影响。设计实验研究。研究对象健康SD大鼠40只。方法大鼠随机分成4组,正常对照组(N组)常规饲养;紫外线强度为146μw/cm^2,每日连续照射时间:实验A组12分钟,B组24分钟,C组48分钟;四组分别于照射第42、84、42、21天取材,TUNEL检测视网膜细胞凋亡,免疫组化法检测bax、bcl-2表达,ELISA实验检测ALDH活性及表达量。主要指标视网膜组织结构观察、视网膜厚度、视网膜细胞凋亡指数、视网膜组织bcl-2、bax表达、ALDH活性及表达量。结果 N组视网膜组织形态结构正常,A、B、C组视网膜组织核间隙增大,排列稀疏、紊乱;N、A、B、C组大鼠视网膜厚度分别是(144.495±1.419)μm、(146.020±1.986)μm、(112.430±1.972)μm、(103.390±1.226)μm,N组与A组差异无统计学意义(P=0.050),但高于B、C两组(P均<0.001);大鼠视网膜细胞凋亡指数A组(11.011±0.540)%、B组(16.880±1.125)%、C组(28.850±1.224)%,与N组(3.070±0.751)%相比均显著升高(P均<0.001);大鼠视网膜bax表达A组(9.530±0.343)%、B组(21.237±0.183)%、C组(33.693±0.227)%,均较N组(5.404±0.154)%明显升高,而bcl-2表达A组(11.738±0.237)%、B组(6.463±0.252)%、C组(1.229±0.162)%,较N组(15.380±0.289)%均显著降低,即bcl-2/bax显著降低(P均<0.001);大鼠视网膜ALDH活性A组(73.924±2.290)IU/L、B组(60.928±1.725)IU/L、C组(55.488±2.172)IU/L,均较N组(84.018±1.893)IU/L显著降低(P均<0.001);ALDH表达量A组(51.725±3.059)ng/ml、B组(43.445±2.695)ng/ml、C组(34.767±3.865)ng/ml,均较N组(62.478±2.247)ng/ml显著降低(P均<0.001)。结论紫外线照射总剂量恒定,随着单次照射剂量增加,视网膜内醛脱氢酶表达下降,视网膜细胞凋亡增加、损伤程度加深。(眼科,2019,28:129-134)

Objective To investigate the effect of different doses of UV irradiation on the aldehyde dehydrogenase (ALDH) activity and expression in retina of rats. Design Experimental study. Participants 40 healthy male SD rats. Method A prospective comparative case-control animal study was conducted on 80 eyes of 40 healthy SD rats. The rats were randomly divided into 4 groups. The normal control group (N group) was routine fed. Experimental rats were exposed to 146 μw/cm^2 UVB irradiation. The A, B and C groups were exposed for 12, 24, 48 minutes per-day respectively. Each group rats were sacrificed and the eyeballs were removed on the 42nd, 84th, 42nd and 21st day respectively. TUNEL was used to detect retinal cell apoptosis. Immunohistochemistry was used to detect the expression of bax and bcl-2. ELISA was used to detect the activity and expression of ALDH. Main Outcome Measures Retinal histological observation, retinal thickness, retinal apoptotic index, bcl-2, bax expression, ALDH activity and expression. Results The morphological structure of retinal tissue was normal in group N. The internuclear spaces of retinal tissues in A, B and C groups were enlarged, with sparse and disordered arrangement. The retinal thickness in N, A, B and C groups was (144.5±1.5)μm,(146.0 ±2.0)μm,(112.4±2.0)μm,(103.4±1.2)μm, respectively. There was no statistically significant difference between group N and group A (P=0.05) in retina thickness. But the retinal thickness was significantly thicker in group N than that of group B and C (both P<0.001). The apoptotic index of retinal cells in A, B, and C groups was (11.011±0.540)%,(16.880±1.125)%, and (28.850±1.224)%, respectively, which was significantly higher than that in group N [(3.070±0.751)%, all P<0.001]. The expression of bax in the retina in A, B, and C groups was (9.530±0.343)%,(21.237±0.183)% and (33.693±0.227)%, respectively, which was statistically higher than that in group N (5.404±0.154)%. While the expression of bcl-2 in the retina in A, B, and C groups was (11.738±0.237)%,(6.463±0.252)% and(1.229±0.162)%, respectively, which was statistically lower than that in group N (15.380±0.289)%. The bcl-2/bax significantly decreased (P<0.001). ALDH activities in A, B, and C groups was (73.924±2.290) IU/L,(60.928±1.725) IU/L and (55.488±2.172) IU/L, respectively, which was statistically higher than that in group N [(84.018±1.893) IU/L, P<0.001]. ALDH expression in A, B, and C groups was (51.725±3.059) ng/ml,(43.445±2.695) ng/ml, and (34.767±3.865) ng/ml, respectively, which was significantly lower than that in group N [(62.478±2.247) ng/ ml, P<0.001]. Conclusions When the total dose of ultraviolet radiation is constant, the expression of ALDH in retina decreases with increase of single irradiation dose, and the apoptosis of retinal cells increases and the degree of radiation damage deepens.