Abstract
Purpose :
Non-arteritic anterior ischemic optic neuropathy (NAION) is a visually disabling disease due to primary damage of retinal ganglion cells (RGC). Currently there is no effective treatment. High doses of omega-3 (ω-3) fatty acids demonstrated a promising effect in other types of ocular pathologies. Therefore, the purpose of this study was to investigate the therapeutic effect of ω-3 using a rat model of anterior ischemic optic neuropathy (rAION) and examine its potential neuro-regenerative and/or neuro-protective properties on RGCs.
Methods :
RAION was induced using laser-induced photoactivation of intravenously administered Rose Bengal in the optic nerve head of adult male Wistar rats. Daily gavage administration of fish oil (1 g/day eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) or phosphate buffered saline (PBS) was given either pre- or post-rAION induction. The animals were assigned to the following treatment groups (n=6/group): PBS treatment, ω-3 pre-treatment (3 days pre-rAION induction), ω-3 immediate treatment (day 0 to day 2 post-rAION induction), ω-3 delayed treatment (day 3 to day 5 post-rAION induction) and ω-3 continuous treatment (day 3 pre-rAION to day 7 post-rAION induction). Gas chromatographic analysis was used to assess the level of blood arachidonic acid (AA)/EPA following treatment on day 0, 3 and 7. Animals used in this study underwent flash visual-evoked potentials (FVEP) to assess visual function and were euthanized 4 weeks post-infarct. Density of RGCs was counted using Fluoro-gold retrograde labeling. Two-tailed Student’s t-test was used for statistical analysis.
Results :
The RGCs’ density (1922 ± 361, 1576 ± 313 and 2720 ± 618 vs 744 ± 183, p < 0.05) and P1-N2 amplitude (48.2 ± 2.4, 44.3 ± 6.1 and 54.2 ± 2.1 vs 25.0 ± 1.3, p < 0.05) were found significantly higher in the groups of immediate, delayed and continuous treatment, compared to that of PBS group. Analysis of blood fatty acids showed that the AA/EPA ratio was greatly reduced on day 3 and day 7 post-treatment compared to day 0 (2.88 ± 0.07, 1.69 ± 0.16 vs 5.87 ± 0.22, p < 0.0001).
Conclusions :
Our findings suggest that administration of ω-3 fatty acids has a neuro-regenerative effect in the rAION as demonstrated both by the RGCs density and FVEP analysis. This might indicate a remarkable turning point in the current treatment approach of patients with NAION; however further work is needed in order to elucidate the underlying mechanism of this effect.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.