Abstract
Purpose :
Glaucoma produces alterations in oxidative stress markers in brain. The use of an antioxidant therapy may hold a promise for treatment. The aim of this study was to evaluate the possible protective role of lipoic acid in oxidative damage of visual cortex in an experimental glaucoma model.
Methods :
Rats were divided in four groups (n=16): glaucoma (G), glaucoma treated with lipoic acid 100 mg/kg i.p. (LG), control received a sham procedure (C), control treated with lipoic acid 100 mg/kg i.p. (LC). Episcleral venous occlusion model in Wistar rats (3 months) was used and 7 days after surgery were euthanized. Brains were removed and visual cortex was separated. These parameters were evaluated: thioredoxin reductase (TR), glutathione peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase (SOD) activities, damage to lipids (TBARS), protein oxidation (PO), total non-enzymatic antioxidants (TRAP) and nitrite levels (NO). The statistical analyses were one-way ANOVA and a post hoc Tukey test.
Results :
Comparing glaucoma group to control group: TR diminished 34 % (14.9 ± 1.0 nmol/ min.mg protein p< 0.05), GPx increased 62 % (7.61± 0.75 nmol/ min.mg protein p< 0.05), GR decreased 61 % (13.0 ± 1.5 nmol/ min.mg protein p< 0.05), PO increased 138% (3.9 ± 0.1 nmol/ mg protein p<0.05), TRAP decreased 50 % (11.7 ± 1.0 nmol/ mg protein p<0.01), NO increased 47 % (2.37 ± 0.12 nmol/ mg protein p<0.05). TBARS increased 133 % ( 2.26 ± 0.23 nmol/ mg protein p<0.001).No significant changes were found in SOD.
Comparing lipoic acid treated glaucoma group to glaucoma group: GR increased 300 % (5.14 ± 1.70 nmol/ min.mg protein p< 0.001), SOD increased 79 % (7.02 ± 0.45 U/ mg protein p<0.001), PO diminished 58% (9.34 ± 1.30 nmol/ mg protein p<0.05), TRAP increased 108 % (5.80 ± 0.48 nmol/ mg protein p<0.01), NO decreased 36 % (3.50 ± 0.28 nmol/ mg protein p<0.05). No significant changes were found in TBARS, GPx and TR.
Conclusions :
Glaucoma induces an increase in prooxidants, a decay in non-enzymatic antioxidants, an increase in protein and lipid damage and a deficient GSH recycling. The protective role of lipoic acid in oxidative damage in glaucoma could be evidenced by the increase in non-enzymatic antioxidants and in the activities of antioxidant enzymes. Moreover, the decay in prooxidant species and the improvement in GSH recycling support that lipoc acid could be used as a novel therapy for reducing oxidative damage in glaucoma.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.