High-resolution magic angle spinning 1H NMR spectroscopy of metabolic changes in rabbit lens after treatment with dexamethasone combined with UVB exposure.
BACKGROUND
Long-term steroid treatment and UVB exposure are well-known cataractogenic factors. The purpose of this study was to investigate metabolic changes in the rabbit lens after long-term dexamethasone treatment in combination with UVB exposure, using high-resolution magic angle spinning proton nuclear magnetic resonance (HR-MAS (1)H NMR) spectroscopy to analyse intact lens tissues.


METHODS
Rabbits received topical doses of 0.1% dexamethasone or 0.9% saline (50 microl) four times daily for 36 days. On day 37, the eyes were exposed to UVB radiation (2.05 J/cm(2)). Twenty-four hours later the animals were killed, and HR-MAS (1)H NMR spectra of lens tissues were obtained.


RESULTS
More than 15 major metabolites were assigned in NMR spectra of rabbit lenses. The combined treatment with dexamethasone and UVB induced large reductions in the concentration of reduced glutathione, inositols, taurine and lactate compared with normal lenses. Concurrently, the levels of glucose, sorbitol and sorbitol-3-phosphate were increased. After exposure to UVB radiation only, the most significant finding was a decrease in the concentration of lactate. No lens opacities were detected.


CONCLUSIONS
HR-MAS (1)H NMR spectroscopy was found to be an efficient tool for analysis of intact lens tissues. High-resolution NMR spectra of intact lens tissue enabled metabolic changes to be quantified. Long-term treatment with dexamethasone combined with UVB exposure induced substantial metabolic changes, dominated by osmolytic regulation processes and loss of glutathione.
Saether
Oddbjørn
O
Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway. oddbjorn.sather@medisin.ntnu.no
Risa
Oystein
O
Cejková
Jitka
J
Krane
Jostein
J
Midelfart
Anna
A
D000287:Administration, Topical; D000818:Animals; D002386:Cataract / Q000209:etiology / Q000378:metabolism*; D003131:Combined Modality Therapy; D003907:Dexamethasone / Q000633:toxicity*; D005938:Glucocorticoids / Q000633:toxicity*; D005947:Glucose / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006600:Hexosephosphates / Q000378:metabolism; D007294:Inositol / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D007908:Lens, Crystalline / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D011522:Protons; D011817:Rabbits; D011833:Radiation Injuries, Experimental / Q000209:etiology / Q000378:metabolism*; D013012:Sorbitol / Q000378:metabolism; D013654:Taurine / Q000378:metabolism; D014466:Ultraviolet Rays
D005938:Glucocorticoids; D006600:Hexosephosphates; D011522:Protons; C059844:sorbitol 3-phosphate; D013654:Taurine; D019344:Lactic Acid; D007294:Inositol; D013012:Sorbitol; D003907:Dexamethasone; D005978:Glutathione; D005947:Glucose