Neuroprotective effect of α-lipoic acid on cultured retinal ganglion cells under elevated pressure in vitro

Objective To observe the neuroprotective effect of α-lipoic acid (ALA) on cultured retinal ganglion cells (RGC-5) under elevated pressure in vitro.Methods Cultured RGC-5 cells were divided randomly into 4 groups,including normal control group (group A),negative control group (group B),elevated pressure group (group C) and elevated pressure + ALA group (group D).The cells of group A and C were not intervened with ALA.The cells of group B were treated with 200 μmol/L ALA.The cells of group D were treated with different concentrations of ALA (50,100,200 μmol/L) for one hour.Then cells of group C and D were exerted to 50 mm Hg (1 mm Hg=0.133 kPa) for 24 hours,while the cells of group A and B were exerted to normal pressures for 24 hours.The cell viability was measured using the methyl thiazolyl tetrazolium (MTT) assay and apoptosis was evaluated using 4',6 diamidino-2-phenylindole (DAPI) staining.Expression of MnSOD was determined by real-time polymerase chain reaction (RT-PCR)and Western blot,respectively.Results The cell viability of group B was (65.6 ± 3.4) ％,which lower than that in group D of three concentrations of ALA[ (75.1± 3.3)％,(81.8 ± 2.9 ) ％,(87.9 ± 3.1 ) ％ ],the differences were significantly (t =5.108,10.007,12.513; P＜0.05).DAPI staining revealed that characteristic apoptotic changes,such as chromatin condensation,convoluted nuclei with cavitations,fragmentation of the nucleus,and apoptotic bodies appeared in RGC-5 cells after 24 ours pressure.There was almost no evidence of apoptosis in group D.RT-PCR and Western blot analysis revealed that the expression of MnSOD mRNA and protein were weakly expressed in group C compared with control A (t=22.045,26.979; P＜0.01).Compared group C with group D,the level of MnSOD mRNA and protein in group D increased significantly (t=9.171,12.267,23.567,7.723,12.009,28.198;P＜0.05).In addition,the presence of ALA was found to inhibit hydrostatic pressure induced damage of RGC-5 cells in a dose-dependent manner (F=134.273,194.597;P＜0.01).Conclusion ALA can effectively improve the expression of MnSOD in RGC-5 cells under the condition of elevated pressure,enhance the ability of RGC-5 cells against oxidative damage. Key words: Retinal ganglion cells/ pathology;  Thioctic acid/therapeutic use;  Cells, cultured; Animal experimentation