Objective: To explore the effects and mechanisms of isoflovone(IS) on spatial learning

memory and monoamine neuro-transmitte

gonadotropin-releasing hormone(GnRH) inovariectomized rats. Method: The fifty Sprague-Dawley rats were ovariectomized. Ovariectomized rats were randomly divided into five groups

model group

estradiol benzoate(EB) group

IS low dose group

IS middle dose group

IS high dose group. EB group were treated with estradiol benzoate(0.2 mg·kg-1) by intraperitoneal injection once a week. IS groups were treated with IS(30

60

120 mg·g-1·d-1) by gavage one time daily. The spatial learning and memory performance were evaluated with Morris watermaze task. The contents of monoamine neuro-transmitter in hippocampus were measured

and GnRH in hypothalamus was measured. Result: ① As compared with control group

the latency period of model group increased significantly(P<0.05).Compared with model group

the latency period of EB group and IS middle dose group decreased significantly(P<0.05).②As compared with control group contents of norepinephrine (NE)

dopamine (DA) and 5-hydroxytryptamine (5-HT) in hippocampus of model group decreased significantly(P<0.05). As compared with model group

contents of NE in hippocampus of IS high dose group increased significantly(P<0.05).As compared with model group

contents of DA and 5-HT in hippocampus of IS middle dose group

EB group increased significantly(P<0.05). ③As compared with control group

contents of GnRH in hypothalamus of model group increased significantly(P<0.05).As compared with model group

contents of GnRH in hypothalamus of IS middle and high dose group

EB group decreased significantly(P<0.05). Conclusion: Isoflovone can improve the ovariectomized rats' impairment of spatial learning and memory by increasing contents of NE

DA

5-HT in hippocampus. Otherwise

isoflovone can decrease contents of GnRH in hypothalamus.