The Effect Of High-Dose Ascorbic Acid On Oxidative DNA Damage And Cellular Function In Rats

Objective To investigate the effects of high-dose vitamin C(VC) on DNA oxidative damage and cellular function.Methods 54 Wistar rats, weighed from 80g to 100g, were randomized into 4 groups, each of which was supplemented with amount of 0, 2000, 5000, 10000mg/kg of VC in diet respectively. The first group was control. The period of the trail was 8 weeks. The samples of the blood were collected by the end of the trial, and the urine in the middle of the trial. The levels of SOD and MDA, and GSH-Px activity in serum or erythrocyte membrane were examined by Kits. The erythrocyte membrane fluidity was determined by fluorescence polarization method. DNA damage was analyzed by SCGE, and O6-MeG was analyzed by high performance capillary zone electrophoresis. The transformation of Lymphocytes was detected by the method of MTT.Results After 8 weeks' trial, the results were showed that the contents of vitamin C in serum and adrenal gland were increased in VC supplement groups. The VC contents of the 5000 and 10000mg/kg diet groups were 460. 00 and 515. 97 g/100mL respectively, which was higher than one in the control (P<0. 05, P<0. 01). The serum vitamin C level in 10000mg/kg diet group was 27. 2% higher than one in the control group (P<0. 01) and 21.2% higher than that of 2000 mg/kg diet group (P<0. 01). The differences between levels of vitamin C in adrenal gland were found in the four groups (F=3. 683,P<0. 05). The VC content in adrenal gland of 10000mg/kg diet group was increased by 40. 1% compared to one in the control group (P<0. 01) and increased 28. 7% compared to that of 2000mg/kg diet group (P<0. 05).Spontaneous DNA damage had no differences in the four groups (P>0. 05), while DNA damage induced by 10 mol/L H2O2 had significant differences(F=3. 310, P<0. 05). The DNA damage was gradually aggravated when the dose of VC supplementation was increased. The level of DNA damage in 5000mg/kg diet VC group was 28% higher than one in the control group (P<0. 05)and that of the 10000mg/kgdiet VC group was 49% higher than one in the control (P<0. 01). There were great differences in the level of O6-megth-ylguanine in urine among the four groups(F=4. 276, P = 0. 01). The level of O6-MeG in the 10000mg/kgdiet VC group was the highest and 36% higher than one in the control (P<0. 05).The differences between levels of serum SOD in those groups were found (F=6. 213, P<0. 01). The serum level of SOD in 2000 mg/kg diet group was higher than one in the control group (P<0. 05), while the serum level of SOD in 10000mg/kg diet group waslower than one in the control group (P<0. 05). The GSH-Px activity in erythrocyte membrane of those groups was 182. 22, 213. 58, 138. 13 and 102. 11U respectively. The GSH-Px activity of erythrocyte membrane in 2000 mg/kg diet group was the highest, but there was no difference compared to control group(P>0. 05). The GSH-Px activity of erythrocyte membrane in l0000mg/kgdiet group was the lowest and reduced 44. 0% compared to that of control group (P<0. 05).The level of serum MDA in the 2000mg/kgdiet group was the lowest and decreased 25. 7% than control group (P<0. 01). The level of serum MDA in 10000mg/kg diet group was the highest and 20. 3% higher than one in the control (P<0. 05). The level of MDA in erythrocyte membrane of 2000mg/kg diet group was the lowest and decreased 44. 4% compared to one in the control (P<0. 01).No matter P or , there were significant differences in the four groups (P<0. 05). The fluorescence polarization of erythrocyte membrane in the 2000mg/kgdiet groups was the lowest and lower than one in the control (P<0. 05). The fluorescence polarization of erythrocyte membrane in 10000mg/kg diet was the highest, but there was no difference compared to that of the control(P>0. 05). There were no differences in the transformation of Lymphocytes among those groups (F=0. 485,P>0. 05), while the transformation of Lymphocytes in the 2000mg/kgdiet group was significantly increased compared to that of the control and the 10000mg/kgdiet group (P<0. 05).Conclusion (1)Supplementing sl...