The subthreshold micropulse laser treatment of the retina restores the oxidant/antioxidant balance and counteracts programmed forms of cell death in the mice eyes

Purpose: Subthreshold micropulse laser (SMPL) has been increasingly used for the treatment of different retinal and choroidal macular disorders. However, the exact mechanisms of action have not yet been clearly defined. Therefore, we aimed to examine the role of SMPL treatment in the modulation of oxidant/antioxidant systems, apoptosis and autophagy in the mice eyes. Methods: A specific laser contact lens for retina was positioned on the cornea of 40 mice (20 young and 20 old) in order to focus the laser on the eye fundus for SMPL treatment. Within 6 months, 20 animals received one treatment only, whereas the others were treated three times. Eye specimens underwent histological analysis and were used for thiobarbituric acid reactive substances (TBARS) and glutathione (GSH) quantification, as well as for the superoxide dismutase 1 (SOD1) and the selenoprotein thioredoxin reductase 1 (TrxR1) expression evaluation. Western blot was performed for nitric oxide synthase (NOS) subtypes detection and to examine changes in apoptotic/autophagy proteins expression. Results: SMPL treatment reduced TBARS and increased GSH and SOD1 in the mice eyes. It also reduced cytochrome c, caspase 3 expression and activity and cleaved caspase 9, and increased Beclin 1, p62 and LC3β. The effects were more relevant in the elderly animals. Conclusion: Our results showed that SMPL therapy restored the oxidant/antioxidant balance within retinal layers and modulated programmed forms of cell death. Further studies may confirm these data and could evaluate their relevance in clinical practice.