Biochemical changes in selenite cataract model measured by high-resolution MAS 1H NMR spectroscopy

Purpose: To correlate certain levels of lens opacification with high-resolution magic-angle spinning proton nuclear magnetic resonance (HR-MAS H-1 NMR) spectroscopy analysis of the biochemical changes in rat lenses in a selenite cataract model. Methods: Selenite cataract was induced by injecting 13-day-old Sprague-Dawley rat pups with a single subcutaneous dose of sodium selenite (3.28 mg/kg in 0.9% sodium chloride solution). Lens opacification was observed using a photographic slit-lamp microscope at selected time-points 3, 6 and 9 days after selenite injection and was then graded (levels 0, 1 and 2). The animals were killed after the slit-lamp microscopy, lenses were removed and HR-MAS H-1 NMR spectra from intact lenses were obtained. Relative changes in metabolite concentrations were determined after comparison with matched lenses from untreated animals. Results: Photographic slit-lamp microscopy revealed different stages of cataract in all animals treated with selenite. In the high quality HR-MAS H-1 NMR spectra of the lenses, more than 30 different metabolites were identified in each lens. With the exception of taurine, the concentrations of all amino acids showed a significant increase (p < 0.05) in the second level of cataract. By contrast, glutathione (GSH), succinate and phosphocholine concentrations were significantly reduced. Conclusions: For the first time, this study demonstrates the potential to correlate the level of lens opacification with the biochemical changes obtained with HR-MAS H-1 NMR spectroscopy analysis in a selenite cataract model.