Evolution of light scattering and redox balance in the rat lens after in vivo exposure to close-to-threshold dose ultraviolet radiation.

Purpose: To investigate the evolution of cataract development and glutathione redox balance in the rat lens after in vivo close-to-threshold dose exposure to ultraviolet radiation (UVR) around 300 nm.

Methods: Three groups of 10 Sprague-Dawley rats were unilaterally exposed to 8 kJ/m² UVR-300 nm for 15 min, and a fourth group of 10 rats was kept without UVR exposure as nonexposed control animals. The exposed animals were killed at 1, 3 and 7 days after exposure. Both lenses from all animals were extracted and photographed and the intensity of forward light scattering was measured quantitatively. Thereafter, the lenses were homogenized. The concentration of reduced glutathione (GSH) and oxidized glutathione (GSSG), and the activity of glutathione reductase (GR) and glutathione peroxidase (GPx), respectively, were determined spectrophotometrically. The mean paired differences between exposed and nonexposed lenses were used as primary data in the statistical analyses.

Results: All exposed lenses developed cataract. Lens light scattering increased throughout the 7 days after UVR exposure. GSH concentration and GPx rate transiently increased at 1 day after exposure and then decreased throughout follow-up, with GSH concentration having a negative balance at the end. GSSG concentration and GR activity did not change after UVR exposure.

Conclusion: In vivo close-to-threshold UVR exposure induces a gradual increase in rat lens opacification/cataract development and time dependently alters the redox balance in the lens.