Regulatory effect of edaravone on the photoreceptor autophagy at the early stage of experimental retinal detachment in rats

Objective

To investigate the effect of edaravone, a free radical scavenger, on the regulation of retinal autophagy and the protection of photoreceptor cells at the early stage of experimental retinal detachment (RD) in rats.

Methods

Fifty-one adult male Sprague-Dawley rats were used for RD model establishment, and another 24 rats were served as PBS injection group.The RD model was established via subretinal injection of 0.5% sodium hyaluronate into the right eye of the rats and the rats with successful modeling were randomly divided into RD model group and edaravone treatment group.The rats in the edaravone treatment group were given edaravone of 3 mg/kg intraperitoneally, twice a day after modeling, and the rats in the PBS injection group and RD model group were given equal volume of normal saline.Rats were sacrificed on the 1st day, 3rd day and 7th day following modeling.The T-superoxide dismutase (T-SOD) activity and malondialdehyde (MDA) content in the intraocular fluid was detected.The expression levels of superoxide dismutase 2 (SOD2), nuclear factor E2-related factor 2 (Nrf2), autophagy related gene 4 (Atg4), microtubule-associated protein 1 light chain 3B (LC3B) and other proteins in retinal tissue were identified by Western blot analysis.TUNEL staining was performed on paraffin sections of the whole eyeball to analyze the apoptosis of photoreceptor cells.The study protocol was approved by an Ethics Committee of Xi’an Fourth Hospital (No. 2016016). The use and care of animals complied with the Regulations on the Administration of Experimental Animals.

Results

The RD area was more than 60% in rat eyes of RD model.There were significant differences in MDA content and T-SOD activity among different groups at various time points (MDA: F_group=385.513, P<0.01; F_time=13.021, P<0.01.T-SOD: F_group=48.865, P<0.01; F_time=7.700, P=0.003). Compared with the PBS injection group, the MDA concentration was significantly increased and the T-SOD activity was significantly decreased in the RD group and edaravone treatment group on the 1st, 3rd and 7th day after modeling (all at P<0.05). The MDA concentration was significantly reduced and the T-SOD activity was significantly elevated in the edaravone treatment group on the 1st, 3rd and 7th day after modeling in comparison with those of the RD group (all at P<0.05). Compared with the PBS injection group, the relative expression levels of SOD2 and Nrf2 proteins were significantly increased in the RD group and edaravone treatment group on the 1st, 3rd and 7th day after modeling (all at P<0.05), and Atg4 and LC3B-Ⅱ/LC3B-Ⅰ were significantly increased on the 1st, 3rd and 7th day after modeling (all at P<0.05). The expression level of SOD2 in the edaravone treatment group was significantly higher than that in the RD group on the 1st, 3rd and 7th day after modeling (all at P<0.05), and the expression level of Nrf2 was significantly increased in the edaravone treatment group on the 1st and 3rd day after modeling compared with that of the RD group (both at P<0.05), and the expression levels of Atg4 and LC3B-Ⅱ/LC3B-Ⅰ were significantly increased in the edaravone treatment group on the 3rd day after modeling in comparison with those of the RD group (both at P<0.05). No significant TUNEL positive cells were observed in PBS injection group at all time points, and TUNEL positive cells were observed on the 1st, 3rd and 7th day after modeling in the RD group, and the expression level of caspase-3 in the RD group was significantly increased in comparison with that of the PBS injection group (P<0.05). The apoptosis of photoreceptor cells and the expression level of caspase-3 in edaravone treatment group were significantly decreased in comparison with those of the RD group on the 1st, 3rd and 7th day after modeling (all at P<0.05).

Conclusions

The intraperitoneal injection of edaravone, twice a day, can significantly improve the antioxidant capacity of the retina after experimental RD in rats, regulate retinal autophagy and reduce the apoptosis of photoreceptor cells in early-stage RD.