RESUMO
Objective To observe the antioxidant effects of 99Tc-MDP on the brain of aged mice induced by D-galactose.Methods A total of 48 healthy female Kunming mice were divided into 6 groups by random number table method:normal control group,model group,vitamin E (Vit E) group,groups treated with low,middle and high dosages of 99Tc-MDP.Except the normal control group,mice of each group were injected with 10％ D-galactose saline subcutaneously in the neck for 42 d.At the same time,the 99Tc-MDP groups were given different dosages of 99Tc-MDP (1.75× 10-5,3.50× 10-5,0.70× 10-4 μg/g according to the body mass) respectively into abdominal cavity twice a day.Vit E group was given Vit E by intragastric administration from the first day.The model group was injected with saline every day.After behavioral testing,mice serum samples and brain tissue samples were collected for the determination of superoxide dismutase (SOD),malondialdehyde (MDA),glutathione peroxidase (GSH-Px) and monoamine oxidase (MAO)levels.Then the mice were sacrificed and the brain tissue was taken for HE staining.The independent-sample t test was used for data analysis.Results The mice model was established successfully.SOD levels in brain tissue of groups injected with low,middle,high dosages of 99Tc-MDP,Vit E group were (19.06± 6.44),(20.41±4.02),(22.24±3.76),(24.71±5.09) U/mgprot,respectively,all of which were higher than that of the model group((11.32±2.90) U/mgprot;t=3.099 6-6.504 6,P＜0.05 or ＜0.01).There were similar results for GSH-Px (t =2.214 1-4.145 7,P＜0.05 or ＜0.01).MDA and MAO levels in brain tissue of 99Tc-MDP groups were lower than those of the model group (t =2.140 3-3.057 8,all P＜0.05).Compared to normal control group,the hippocampus in model group showed reduced cell number and layers,disordered structure,with part of the cells in smaller volume and abnormal nuclear shape.In Vit E group and the three 99Tc-MDP groups,no significant change of neuron was observed compared with normal control group,the degeneration and necrosis of hippocampal cells were mild compared with model group,the cell number and morphology were normal,and the structures were clear.Conclusion 99Tc-MDP may increase the activities of SOD,GSH-Px and reduce the levels of MDA and MAO in brain tissue of aged mice,thus it may be helpful in delaying the brain aging.