Objective To determine the effects of genistein and daidzein on the proliferation and survival of the hippocampal neural cells and underlying mechanism. Methods H19-7/IGF-IR neural cell line was cultured in phenol red free DMEM absented of serum for 72h. Genistein, daidzein or 17β-estradiol was added to the culture at various concentrations. Their proliferation and protective effects on the neuronal cells were determined by BrdU and MTT assay respectively. The effect of phytoestrogens on cell cycle regulation was determined using flow cytometry. The effects of the soy isoflavones on brain-derived neurotrophic factor (BDNF) expression were determined by ELISA and RT-PCR respectively. Results It was observed that, with 72h of treatment, 20nM and 200 nM 17B-estradiol significantly promoted the neuronal cell proliferation at 33% and 36% ;20nM and 200nM genistein significantly promoted the neuronal cell proliferation at 15% and 13% ; 200nM daidzein significantly promoted the neuronal cell proliferation at 11% compared to the control (P＜0.05). Genistein and daidzein induced an significantly increase in the S phase arrest at (17.64 ± 0.43) % and (19.48 ± 1.01) % compared to the control (P ＜ 0. 05). Moreover, genistein and daidzein significantly increased the expression of mature BDNF and BDNF mRNA level (P＜0.05). The effect of genistein and daidzein on hippocampal neuronal cell proliferation was blocked by K252a, selective inhibitor of tyrosine kinase receptors. Conclusion Genistein and daidzein improved hippocampal neuronal cell proliferation and viability in vitro. The effects might be mediated by increasing in BDNF expression.

Objective To study the effect of Eclipta alba on learning and memory ability and brain derived neurotrophic factor(BDNF) in brain of Alzheimer's disease (AD) model rats.Methods Healthy adult SD rats were randomly divided into control group,model group,low dosage group and high dosage group.There were 10 rats in each group.The model of Alzheimer's disease was established with subcutaneous injection of D-galactose and microinjection Aβ25-35 on bilateral hippocampus.All rats were treated with saline solution or different dosage of Eclipta alba respectively lasting 8 weeks.Then the ability of learning and memory of AD rats was evaluated by the Morris water maze test.The levels of expression of BDNF in brain were determined by immunohistochemical staining method and Western Blot method.Results The Morris water maze test:the average escape latent period prolonged besides the percentage of the swimming time in the target quadrant from the total swimming time and the times across the platform((34.14± 1.43) s,(33.71±3.82) ％,(3.40±0.70) times) decreased significantly in model group compared with control group((18.83±0.62) s,(41.98±3.96) ％,(5.40± 1.17) times,P＜0.01).The average escape latent period shortened besides the percentage of the swimming time in the target quadrant from the total swimming time and the times across the platform increased significantly in high dosage group compared with the model group (P＜0.01).Immunohistochemical staining and Western blot:the level of expression of BDNF in brain in model group was prominently less than control group (P＜ 0.01).The BDNF level in drug treated groups was prominently higher than model group(P＜0.01).The expression of BDNF increased with the drug dosage increasing.Conclusion Eclipta alba can improve the learning and memory function of AD rats by enhance the expression of BDNF.