Abstract
Purpose: :
Astaxanthin (AST), a red carotenoid found in marine animals and vegetables, has potential clinical applications due to its higher antioxidant activity than β-carotene and α-tocopherol. Acute ultraviolet (UV) exposure causes photokeratitis and induces various inflammatory changes in the cornea. In the present study, we examined whether topical administration of AST has therapeutic effects on UV-photokeratitis in mice.
Methods: :
Six- to 8-week-old C57BL/6 male mice were used. C57BL/6 male mice were administered AST in instillation form at the concentrations of 1 mg/ml, 0.1 mg/ml, and 0.01 mg/ml to right eyes, whereas left eyes were instilled with vehicle alone. After the instillation, the mice were irradiated with UVB at the dose of 400 mJ/cm2 under anesthesia. Eyeballs were collected 24 hours after irradiation, and corneal damage was evaluated by TUNEL. As an in vitro study, NIH-3T3 cells irradiated with UVB were cultured with or without AST. Cytotoxicity was quantified with LDH assay.
Results: :
UVB irradiation caused disruption of the corneal basement membrane and UVB irradiation caused disruption of the corneal basement membrane and thinning of the corneal epithelium; however, the epithelium was well preserved after irradiation in AST-treated corneas. The corneal epithelium thickness was 35.75±1.7, 29.75±1.7 and 8.5±2.8 µm in mice treated with 1, 0.1 and 0.01 mg/ml of AST, respectively. The mean corneal epithelial thickness was 4.75±4.6 µm in untreated eyes after irradiation. Non-irradiated corneal epithelium was 38.25±2.5 µm thick. Apoptotic cells were counted as 2.75±3.7, 2.25±2.8, 19.0±3.2, and 23.0±5.3 in eyes treated with 1, 0.1, 0.01, and 0 mg/ml of AST, respectively. Significantly fewer apoptotic cells were observed in AST-treated UV-irradiated corneas than controls (p<0.01). In vitro study showed less cytotoxicity in AST-treated cells after UVB-irradiation. The percentages of mean cytotoxicity after irradiation were 23.0±5.3%, 59.25±5.3%, 77.75±7.6 %, and 86.75±4.3% in wells added 1, 0.1, 0.01, and 0 mg of AST, respectively.
Conclusions: :
These results suggest that AST has the protective effect against UVB damage in vivo and in vitro. AST might be a promising naturally-derived material protecting ocular surface from the toxicity of ultraviolet.
Keywords: cornea: epithelium • cell survival • antioxidants