Abstract:

Objective To investigate the time-dependent pattern of blue light-induced retinal damage in mice, establish a suitable animal model, and evaluate the protective effects of a compound formula containing lutein esters, DHA algal oil, Lycium ruthenicum, and other ingredients used as both food and medicine. Methods Thirty-two of the 56 SPF-grade male C57BL/6J mice were randomly divided into a control group and model groups (1 h, 3 h, and 6 h irradiation) (n=8 per group) to determine the optimal blue light irradiation time. First, mice were exposed to blue light from a 467 nm light-emitting diode at (5 000±200) lx for 1 h, 3 h, and 6 h, respectively. Retinal histopathology and thickness were examined using hematoxylin‑eosin (HE) staining. Serum malondialdehyde (MDA) and glutathione (GSH) levels were measured using assay kits. Retinal inflammatory cytokine mRNA expression was assessed by real-time fluorescent quantitative reverse transcription PCR. After 3 h of blue light exposure was confirmed as the appropriate modeling condition, the remaining 24 mice were used in an intervention experiment to evaluate the protective effect of the eye-protective compound formula on blue light-induced retinal damage. The mice were administered the compound formula (1 000 mg·kg^-1·d^-1) by gavage for 14 days, followed by 3 h of blue light irradiation, and the same indicators were evaluated as described above. Results With prolonged irradiation time, the thickness of each retinal layer gradually decreased (P<0.05 to P<0.01) and cell arrangement became disordered. Serum MDA levels progressively increased (P<0.01), while GSH levels gradually decreased (P<0.01). The mRNA expression of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in retinal tissue was significantly upregulated with increasing irradiation time. The 1 h irradiation group showed only minor changes (P>0.05), whereas the 6 h irradiation group exhibited the most pronounced changes (P<0.000 1). Therefore, 3 h of blue light irradiation (P<0.001), which showed significant yet moderate differences in all indicators, was selected as the subsequent modeling condition. After intervention with the eye-protective compound formula, compared with the model group, serum MDA level was significantly reduced (P<0.01), and serum GSH level was significantly increased (P<0.05). The expression levels of retinal inflammatory cytokines IL-1β (P<0.000 1), IL-6 (P<0.001), and TNF-α (P<0.01) were significantly downregulated. Total retinal thickness (P<0.01), as well as the thicknesses of the inner plexiform layer (P<0.05), inner nuclear layer (P<0.05), outer plexiform layer (P<0.05), and outer nuclear layer (P<0.01), were significantly increased compared with the model group. Histopathological examination also showed that the regularity and density of retinal cell arrangement were markedly better than those in the model group. Conclusion Blue light irradiation at a specific illuminance for 3 h can establish a stable mouse model of retinal damage. The compound formula alleviates retinal damage through antioxidant and anti-inflammatory pathways, providing an experimental basis for the development of related functional foods.

Key words: Lutein, Blue light, Retina, Oxidative stress, Inflammation, Functional food, C57BL/6J mice