Abstract:

Objective To investigate the relationship between serum nucleic acid oxidative damage products [DNA related substance 8-oxo-7,8-dihydro-deoxyguanosine（8-oxo-dGsn） and RNA related substance 8-oxo-7,8-dihydroguanosin（8-oxo-Gsn）] and antioxidant substance selenium,vitamin（Vit） A and Vit E in patients with Alzheimer's disease（AD）. Methods A total of 55 patients with AD and 64 apparently healthy subjects were enrolled. Liquid chromatography tandem mass spectrometry（LC-MS/MS）was used to determine the levels of 8-oxo-dGsn,8-oxo-Gsn,Vit A and Vit E in serum,and the level of selenium in serum was determined by inductively coupled plasma mass spectrometry（ICP-MS）. All the subjects were classified into 4 groups according to ages：<60 years old,60-69 years old,70-79 years old and ≥80 years old groups. Spearman correlation analysis was used to evaluate the correlation between these substances. Results The levels of selenium and Vit A in AD group were lower than those in healthy control group（P<0.01）,and the level of 8-oxo-dGsn was higher than that in healthy control group（P<0.01）. The levels of Vit E and 8-oxo-dGsn had no statistical significance between the 2 groups（P>0.05）. The selenium level in healthy control group was higher than that in AD group（P<0.01）. The level of Vit A in <60 years old and 60-69 years old groups were higher than those in AD group（P<0.01）,and the levels of 8-oxo-dGsn were lower than those in AD group（P<0.05）. There was no statistical significance in Vit A and 8-oxo-dGsn levels between 70-79 years old and ≥80 years old groups（P>0.05）. There was no statistical significance in serum Vit E and 8-oxo-Gsn levels between healthy control group and AD group（P>0.05）. 8-Oxo-dGsn and 8-oxo-Gsn levels were positively correlated with age（r=0.443 and 0.782,P<0.01）,selenium levels were positively correlated with serum Vit A and Vit E（r=0.330 and 0.401,P<0.01）,and 8-oxo-dGsn levels were positively correlated with 8-oxo-Gsn levels（r=0.644,P<0.01）. There was no correlation between the other items（P>0.05）. Conclusions Sera from patients with AD contains high levels of DNA oxidative damage product 8-oxo-dGsn and low levels of antioxidant substance selenium.

Key words: 8-Oxo-7, 8-dihydro-deoxyguanosine, 8-Oxo-7, 8-dihydroguanosin, Selenium, Vitamin A, Vitamin E, Alzheimer's disease