To study the changes in protein expression levels of 8 oxide of guanine in the temporal and frontal lobes in SAMP8(senescence accelerated mice)mice versus SAMR1(control mice).

In the study, we collected 12 SAMP8 mice and 12 SAMR1 mice at different month stage(1m, 4m, 8m, 12m)(n=6, each group). After anesthesia, mice were sacrificed.The temporal and frontal lobe tissues of mice were labeled according to the stereotactic anatomical map of mouse brain and taken up for study.After paraffin sections were made, the expression level of 8 oxide of guanine in brain tissues was detected by immunohistochemical method.

In the same age group at 1 month in the same temporal lobe, the average optical density of 8-oxodG was slightly higher in SAMP8 mice(0.086)than in SAMR1 mice(0.061, t=1.541, P>0.05). There were significant differences in the mean optical density of 8-oxodG in temporal lobe in 4, 8 and 12 months groups between SAMP8 and SAMR1 group(0.101 vs.0.081, 0.147 vs.0.109 and 0.176 vs.0.120, t=2.405, 2.612 and 5.019, respectively, P<0.05). There was no significant difference in the average optical density levels of 8-oxodG in frontal lobe in 1 and 4 months groups between SAMP8 and SAMR1 mice(0.044 vs.0.030, 0.062 vs.0.046, t=1.843 and 1.163, respectively, P>0.05), while the average optical density levels of 8-oxodG in 8 and 12 months groups(0.090 and 0.138)were higher than those of SAMR1 mice in the same age group(0.049 and 0.063)(t=5.327 and 4.88, P<0.01). There was no significant difference in the average optical density of 8-oxoG in temporal lobe in 1 month group between SAMP8 and SAMR1 mice(0.099 vs.0.066, t=1.956, P>0.05). There were significant differences in the average optical density levels of 8-oxoG in temporal lobe in 4, 8 and 12 months groups between SAMP8 and SAMR1 mice(0.119 vs.0.076, 0.148 vs.0.094 and 0.173 vs.0.101, t=4.033, 3.042 and 5.328, respectively, P<0.01). There was no significant difference in the average optical density levels of 8-oxoG in frontal lobe in 1 month and 4 months groups between SAMP8 and SAMR1 mice(0.049 vs.0.039, 0.058 vs.0.056, t=0.713 and 0.172, respectively, P>0.05). The average optical density of 8-oxoG in frontal lobe in 8 months and 12 months groups had significant differences between SAMP8 and SAMR1 mice(0.087 vs.0.058, 0.12 vs.0.063, t=2.261 and 4.185, P<0.05). In addition, we also found that the average optical density of 8 oxide of guanine in same SAMP8 mice at the same age was higher in temporal lobe than in frontal lobe.

The protein levels of 8-oxodG and 8-oxoG are increased with age, and the damage caused by nucleic acid oxidation is more severe in temporal lobe than in frontal lobe in SAMP8 mice.

Guanine; RNA oxidation; DNA oxidation; Temporal lobe; Front lobe