Genistein attenuates memory impairment in Alzheimer's disease via ERS-mediated apoptotic pathway in vivo and in vitro.

Genistein (GS), an isoflavone compound found in soybean, plays a neuroprotective role in Alzheimer's disease (AD). However, the mechanism of its action remains unclear. Herein, binding ability between GS and GRP78 was predicted by molecular docking, and the effect of GS in vivo and vitro were further studied. In this study, the effects of GS on learning and memory ability, changes of hippocampal neurons and ultrastructure of hippocampal CA3 region in AD rats were investigated. Besides, the protein or mRNA levels of the related proteins were detected. The results showed GS could effectively improve the learning and the memory ability, reduce the damage of hippocampal neurons, and decrease the protein or mRNA expression levels of GRP78, CHOP, Caspase-12, Cle-Caspase-9, Cle-Caspase-3, PERK, and p-PERK. Taken together, our data reveal GS has a neuroprotective effect by inhibiting the ERS-mediated apoptotic pathway, which may be a new therapeutic target for the treatment of AD.

Chrysophanol improves memory ability of d-galactose and Aß25-35 treated rat correlating with inhibiting tau hyperphosphorylation and the CaM-CaMKIV signal pathway in hippocampus.

This study was aimed to investigate the effect of Chrysophanol (CHR) on Alzheimer's disease. We also attempted to understand the potential mechanisms. An Alzheimer's disease rat model was established using an intraperitoneal injection of d-galactose combined with an intracerebral injection of amyloid-ß peptide (25-35), and the effect of CHR on the learning and memory ability, the hippocampal neurons change, the ultrastructure of the hippocampal CA1 region, the protein levels of CaM, CaMKK, CaMKIV, p-CaMKIV and p-tau in the hippocampus of rats were studied. The results showed that CHR significantly improved the cognitive deficits, alleviated hippocampal neurons damage, prevented the ultrastructure alteration of neurons in hippocampal CA1 region, and reduced the protein levels of CaM, CaMKK, p-CaMKIV and p-tau in the hippocampus of AD rats. These results suggested that Chrysophanol could improve memory ability of Alzheimer's disease rat by inhibiting tau hyperphosphorylation and the CaM-CaMKIV signal pathway.

Huang-Pu-Tong-Qiao Formula Ameliorates Tau Phosphorylation by Inhibiting the CaM-CaMKIV Pathway.

Alzheimer's disease (AD) is a complex neurodegenerative disease. It is a chronic, lethal disease in which brain function is severely impaired and neuronal damage is irreversible. Huang-Pu-Tong-Qiao (HPTQ), a formula from traditional Chinese medicine, has been used in the clinical treatment of AD for many years, with remarkable effects. However, the neuroprotective mechanisms of HPTQ in AD have not yet been investigated. In the present study, we used AD models in vivo and in vitro, to investigate both the neuroprotective effect of HPTQ water extracts (HPTQ-W) and the potential mechanisms of this action. For the in vivo study, after HPTQ intervention, the Morris water maze test was used to examine learning and memory in rats. Transmission electron microscopy and immunofluorescence methods were then used to investigate neuronal damage. For the in vitro experiments, rat primary hippocampal neurons were cultured and cell viability was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. Additionally, mRNA levels of CaM, CaMKK, CaMKIV, and tau were examined using qRT-PCR, and protein expression of CaM, CaMKK, p-CaMKIV, and p-tau were examined using western blot. In vivo, we revealed that HPTQ significantly improved learning and memory deficits and attenuated neuronal damage in the AD rat model. Furthermore, in vitro results showed that HPTQ significantly increased cell viability in the AD cell model. We also demonstrated that HPTQ significantly decreased the mRNA levels of CaM, CaMKK, CaMKIV, and tau and significantly decreased the protein expressions of CaM, CaMKK, p-CaMKIV, and p-tau. In conclusion, our results indicated that HPTQ improved cognition and ameliorated neuronal damage in AD models and implicated a reduction in tau phosphorylation caused by inhibition of the CaM-CaMKIV pathway as a possible mechanism.

[Protective effects of genistein on Aß25₋35-induced PC12 cell injury via regulating CaM-CaMKIV signaling pathway].

Genistein is a kind of isoflavone compounds， also called phytoestrogens， with clinical effects on cardiovascular disease， cancer and postmenopausal-related gynecological diseases， and also has the potentiality in the prevention and treatment of Alzheimer's disease(AD). In this study， the protective effect of genistein on Aß25₋35-induced PC12 cell injury and effect on CaM-CaMKIV signaling pathway were observed to investigate its mechanism for AD. PC12 cells were cultured in vitro and then the safe concentration of genistein and the modeling concentration and optimal time point of administration of Aß25₋35 were screened by MTT assay. After being pretreated with different concentrations of genistein(25， 50， 100 µmol·L⁻¹) on PC12 cells， the AD model of PC12 cells was induced by Aß25₋35. Then the survival rate of cells was detected by MTT assay; morphological change of cells was observed under the inverted microscope， and apoptosis of cells was assessed by AO/EB fluorescence staining; the neuroprotective effects of genistein on AD cell model were observed and the optimal concentration of genistein was determined. Expressions of mRNA and protein levels of CaM， CaMKK， CaMKIV and tau were detected by qRT-PCR and Western blot assay， respectively. The results showed that as compared with the blank group， the cell survival rate was decreased; the cell damage and apoptosis were increased; and the expressions of mRNA and protein levels of CaM， CaMKK， CaMKIV and tau were increased in AD model group. Genistein could significantly improve the cell survival rate， reduce the cell damage and apoptosis of AD cell model， and significantly down-regulate the expressions of mRNA and protein levels of CaM， CaMKK， CaMKIV and tau of AD cell model. These results indicated that genistein has obviously neuroprotective effect on the AD cell model induced by Aß25₋35， and the mechanism may be related to the down-regulation of CaM-CaMKIV signaling pathway and Tau protein expression.