Protective effect of soy isoflavone on cognition disorder in Alzheimer's disease model rats

Objective: To investigate the protection role of soy isoflavone on the learning deficiency induced by Aβ25～35 in rats. Methods: The model rat was made with Aβ25～35 stereotactic injection into bilateral hippocampus and the control rat was injected with normal saline in the same way. Soy isoflavone was administered with different dosage (25, 50 mg·kg-1 ) . Estradiol benzoate (1 mg·kg-1 ) was injected once every three days 24 hours after the injection of Aβ25～35 for 18 days. Morris water maze test was done at one week before animals were killed. Results: Aβ25～35 caused learning deficiency in rats. Administration of soy isoflavone could decrease the latency of escaping and increase the percentage of swimming distance in the platform quadrant and the number of entries in the target area. Isoflavone 50 mg·kg-1 group was better than isoflavone 25 mg·kg-1 group. Conclusion: Soy isoflavone can improve the learning and memory ability of AD model rats, this indicates primarily that soy isoflavone has the effect of anti-dementia.