Abstract
Purpose: :
Purpose of this study was to examine whether trehalose might decrease the oxidative damage of the cornea irradiated with UVB rays.
Methods: :
Adult New Zealand white rabbits were employed in our experiments. Rabbit corneas of both eyes were irradiated with UVB rays (312 nm, a dose per day 0.5 J/cm2). The irradiation took place once a day for four days. During the irradiation, the trehalose in eye drops was applied dropwise on the right eye and buffered saline on the left eye. After the end of irradiation (on day four) the animals were left without any treatment for one day and sacrificed (on day five). The central corneal thickness was measured by Pachymeter SP-100 (Tomey Co., Japan) in all rabbits, always before irradiation and also on day five before killing the animals. After the death of animals the corneas were examined spectrophotometrically or immunohistochemically and morphologically. For spectrophotometrical investigation, corneal centers (circles of 6 mm diameter) were measured over a range of 300-650 using a scanning spectrophotometer (HELIOSb 84021). Immunohistochemically, apoptotic corneal cell death (demonstrated by active caspase-3), nitric oxide synthases that generate nitric oxide, toxic peroxynitrite (demonstrated by nitrotyrosine residues), and antioxidant aldehyde dehydrogenase3A1 were examined. Morphologically, the amount of inflammatory cells and corneal neovascularization were followed.
Results: :
Compared to buffered saline, trehalose-treated corneas displayed fewer corneal disturbances in irradiated corneas. The increase in corneal hydration and light absorption were less pronounced and intracorneal inflammation and corneal neovascularization were suppressed. Nitric oxide synthases and nitrotyrosine were less expressed in the cornea and the expression of aldehyde dehydrogenase 3A1 was less inhibited. The apoptotic corneal cell death was greatly diminished.
Conclusions: :
Trehalose reduced UVB-induced oxidative damage as well as changes of corneal optics.
Keywords: apoptosis/cell death • cornea: basic science • radiation damage: light/UV