Abstract: Objective To explore the effect of α-zearalanol (α-ZAL) on β-amyloid (Aβ) induced mice and the mechanism. Methods The model was induced by intracerebroventricular injection of Aβ25-35. The mice were divided randomly into sham group, model group, estradiol benzoate (EB) group (Aβ+EB) as a positive control and α-ZAL (Aβ+α-ZAL) group. Morris water maze was used to evaluate the learning and memory ability. The levels of antioxidant enzymes and nitric oxide system in the brain tissue were detected with spectrophotometric and sotopic method. Results The escape latency was longer in the model group than in the control group (P<0.01), and was shorter in the EB group and α-ZAL group than in the model group (P<0.05). Compared with the control group, the level of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) decreased, and the level of malonaldehyde (MDA), constitutive nitric oxide synthase (cNOS), inducible nitrous oxide synthesis (iNOS), and nitric oxide (NO) increased in the model group (P<0.05); compared with the model group, the level of
SOD and GSH-Px increased, and the level of MDA, cNOS, iNOS and NO decreased in the EB group and α-ZAL group (P<0.05), except the level of SOD and cNOS in hippocampus in α-ZAL group (P>0.05). There was no significant difference between EB group and α-ZAL group (P>0.05). Conclusion α-ZAL could improve the cognitive behavior in Aβ25- 35 induced mice by increasing the antioxidant activities and decreasing the lipid peroxidation.

Key words: Alzheimer's disease, α-Zearalanol, Morris water maze, antioxidant, nitric oxide, mice