title: Pre-exposure to low-power diode laser irradiation promotes cytoprotection in the rat retina.
abstract: The aim of this study was to investigate whether pre-exposure to low-power laser irradiation can provoke an effect on cellular protection in the rat retina. The right eyes of 40 rats were exposed to a 3-mm diode laser beam for 1 min in different light intensities and different experimental sets: group A low power of 60 mW (34.27 J/cm(2) on the retina in consideration of the energy losses along the optical pathway) prior to high power of 80 mW (44.88 J/cm(2) on the retina in consideration of the energy losses along the optical pathway), group B high power, group C low power, group D (the left eyes from the counterpart of group A) and group E (untreated rat eyes) as controls. Morphological retinal change retinas were assessed using light microscopy and/or transmission electron microscopy. Heat shock protein (Hsp) 70 and cleaved caspase 3 protein expression were analyzed by immunohistochemical staining and Western blot. Cellular injury was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay. Hsp 70 expression in the inner plexiform layer and the outer plexiform layer in group A were 73.09 ± 6.49 and 78.03 ± 3.05%, respectively, which was significantly higher (P < 0.05) than those observed in group B (59.07 ± 1.40 and 32.25 ± 4.26%, respectively). The Hsp70/β-actin ratio was 0.49 ± 0.06 in group C, which was significantly higher (P < 0.05) than that of group B (0.27 ± 0.04). Cleaved caspase 3 expression in group C both was significantly lower than that observed in group B. TUNEL staining showed that positive cells in the outer nuclear layer and inner nuclear layer in group A were significantly lower than those of group B. Pre-exposure to a 60-mW (34.27 J/cm(2) on the retina) power laser irradiation stimulates a hyperexpression of Hsp70 together with a hypoexpression of cleaved caspase 3 in rat retina, which may suggest a cellular protective effect.
authors.affiliation: Ophthalmology Department, Ruijin Hospital, Shanghai JiaoTong University, Shanghai, 200025, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Sun
authors.forename: Shisheng
authors.initials: S
authors.lastname: Zhang
authors.forename: Huaping
authors.initials: H
authors.lastname: Liao
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D019610:Cytoprotection; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D054023:Lasers, Semiconductor / Q000627:therapeutic use*; D028022:Low-Level Light Therapy; D008268:Macular Degeneration / Q000532:radiotherapy*; D051381:Rats; D011914:Rats, Inbred BN; D012160:Retina / Q000473:pathology / Q000528:radiation effects*
chemical_list: D000199:Actins; D018840:HSP70 Heat-Shock Proteins; C505410:Casp3 protein, rat; D053148:Caspase 3