Effect of dietary vitamin E and selenium on DNA damage in fresh and frozen tissues.
To determine whether deficiencies of dietary vitamin E and Se can elevate background DNA damage, rats were fed diets deficient in or supplemented with vitamin E (30 and 200 mg/kg diet) and Se (0.2 mg/kg diet) for 8 weeks. DNA damage was measured using the Comet (single-cell electrophoresis) assay and 8-oxodeoxyguanosine (8-oxo-dG) in liver, kidneys, and lymphocytes. We found that a deficiency of vitamin E and/or Se for 8 weeks did not significantly increase DNA damage in freshly isolated liver, kidneys, or lymphocytes. However, deficiency of vitamin E and/or Se for 8 weeks markedly increased DNA strand breaks in frozen kidney (-80 degrees C for 72 hours) and in lymphocytes incubated overnight at 37 degrees C, both of which were effectively prevented by supplementation of Se and vitamin E. However, vitamin E at 200 mg/kg did not afford more protection than it did at 30 mg/kg). Little or no significant increase in DNA damage was found in frozen livers. These results indicate that freezing or freeze-thawing of tissues may cause oxidative damage to DNA when the tissues are deficient in a major antioxidant, and that normal levels of vitamin E (30 mg/kg diet) and Se (0.2 mg/kg diet) are sufficient to prevent the damage. Thus, our results caution against the interpretation of DNA data obtained from frozen rat tissues or cells in animal studies with dietary vitamin E or Se deficiencies.
Chuang
Cheng-Hung
CH
Department of Food Science, National Chung-Hsing University, 250 Kuo-Kuang Road, Taichung, 402 Taiwan, ROC.
Hu
Miao-Lin
ML
D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage*; D015925:Cryopreservation; D004249:DNA Damage / Q000187:drug effects*; D004032:Diet; D007668:Kidney / Q000378:metabolism*; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012643:Selenium / Q000008:administration & dosage* / Q000172:deficiency; D014810:Vitamin E / Q000008:administration & dosage*; D014811:Vitamin E Deficiency / Q000378:metabolism
D000975:Antioxidants; D014810:Vitamin E; D012643:Selenium