Abstract:

 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/cm2 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. （Ophthalmol CHN， 2019, 28： 129-134）

Key words: ultraviolet; , irradiation dose, aldehyde dehydrogenase, retina