Abstract: Objective: To investigate if and how genistein can protect hippocampal neurons against Aβ25-35-induced injury by regulating the Ca2+-calmodulin-dependent protein kinase IV (CaMKIV) pathway. Methods: The hippocampal tissue was taken from neonatal SD rats within 24 h after birth for isolation, purification and culture of neurons as well as identification by immunofluorescence staining. The neuronal cells were randomly divided into four groups: blank control, model, and genistein treatment (50 μmol/L) and estradiol and valerate treatment (10 μmol/L). After being pretreated for 3 h, the hippocampal neurons in all groups except the blank control group were treated with Aβ25-35 to establish a cell injury model. The cell survival rate was detected by methylthiazolyl tetrazolium, the intracellular Ca2+ concentration was detected using a fluorescent probe, and the expression of calmodulin (CaM), calcium/calmodulin dependent protein kinase kinase (CaMKK), phosphorylation calmodulin-dependent protein kinase (p-CaMKIV) and p-Tau were detected by Western blot. Results: Immunofluorescence showed that the hippocampal neurons were successfully isolated. Compared with the blank control group, the survival rate of hippocampal neurons in the model group was significantly decreased (P < 0.01), and the intracellular concentration of Ca2+ was significantly increased as well as the protein expression of CaM, CaMKK, p-CaMKIV and p-Tau (P < 0.01). Compared with the model group, genistein significantly increased the survival rate of hippocampal neurons (P < 0.01), decreased the intracellular concentration of Ca2+ (P < 0.01), and down-regulated CaM, CaMKK, p-CaMKIV and p-Tau protein expression (P < 0.01). Conclusion: Genistein has an obvious protective effect on hippocampal neuron damage induced by Aβ25-35, which may be mediated by the Ca2+-CaMKIV signaling pathway.

Key words: Alzheimer’s disease; genistein; Ca2+-CaMKIV signaling pathway; hippocampal neurons