Abstract: Objective：To explore the effect of vitamin  B12 supplementation in early life on DNA methylation level and Aβ toxicity in hippocampal neuron cells(HNCs) and its mechanism.Methods：HNCs in 12 h of birth of the newborn rats were taken for culture in vitro, which were randomly divided into 5 groups: blank group, model group, low dosage vitamin  B12 group, medium-dosage group and high-dosage group. Different dosages of vitamin  B12 were given for intervention. HPLC method was used to determine the level of DNA methylation; meanwhile, observe the effect of early intervention by vitamin  B12 on proliferation rate(PR) and apoptosis rate(AR) of mature HNCs after Aβ1-42  toxification, MDA content, SOD activity and GSH-PX activity.Results：The DNA methylation level of HNCs intervened by vitamin  B12 at early stage was significantly lower than the control group(P<0.05);Aβ toxification could significantly decrease the PR and increase the AR of HNCs, and increase MDA content and reduce the activity of SOD and GSH-PX(P<0.05). Compared with model group, vitamin  B12 supplementation in early life could increase PR of mature HNCs after Aβ toxification, decrease the AR, reduce MDA content, and increase the activity of SOD and GSH-PX, the difference being statistical((P<0.05).Conclusion:Supplementation of vitamin  B12  in early life is helpful to decrease the methylation level of neuron cells, which plays an anti-Aβ neurotoxicity role in mature neuron cells, participates in oxidative stress of neuron cells, promotes cell proliferation and slows down apoptosis of neuron cells.

Key words: Alzheimer disease;Vitamin , B12;DNA methylation;Prevention