Neuroprotective effects of EPA and DHA fatty acids in the DBA/2J hereditary glaucoma mouse model

Purpose To determine whether omega‐3 ( ω ‐3) supplementation used alone or in combination with timolol, protect against inflammation and RGC loss in DBA/2J mouse model Methods DBA/2J mice were assigned to the following treatment groups ( n = 20/group) with balanced sex: ω ‐3 plus timolol, ω ‐3,timolol and untreated. All treatments were started at the age of 8.5 months and continued until sacrifice at 11.5 months of age. Mice received daily gavage administration of fish oil (EPA/DHA = 2:1) and/or topical instillation of timolol (0.5%) once a day. The dosage of EPA/DHA was adjusted so that the AA/EPA blood ratio was within therapeutic range of 1–1.5 using Gas chromatography. RGC densities were counted using Brn3a antibody. Real‐time polymerase chain reaction was performed to determine the gene expression of TNF‐ α , IL‐1 β and IL‐18 inflammatory molecules in the retinas. Western blot analysis was used to test the protein expression of IL‐18 in the retinas. Results RGC densities were found significantly higher in the groups of ω ‐3 plus timolol (p = 0.0041), ω ‐3 (p = 0.0097) and timolol (p = 0.0011) compared to that of untreated group. No significant differences were seen in the gene expression levels of TNF‐ α (p = 0.0790, p = 0.0742, p = 0.1006),IL‐1 β (p = 0.1242, p = 0.4865, p = 0.5280) and IL‐18 (p = 0.6320, p = 0.3351, p = 0.3663) in the retinas between the groups of ω ‐3 plus timolol, ω ‐3 or timolol and the untreated group. Protein expression of IL‐18 was significantly reduced in the retinas of ω ‐3 treatment group compared to that of untreated (p = 0.0367) Conclusions Our findings suggest not only that ω ‐3 supplementation (AA/EPA ratio <1.5) has a neuro‐protective effect in the DBA/2J, as demonstrated by the RGC density analysis, but also provide insight into the role of inflammation in the pathogenesis of glaucoma and indicate that ω ‐3 administration could be beneficial in controlling inflammation in the retina.