Liquiritigenin inhibits Aβ25–35-induced neurotoxicity and secretion of Aβ1–40 in rat hippocampal neurons

Abstract

Aim: To examine whether liquiritigenin, a newly found agonist of selective estrogen receptor-β, has neuroprotective activity against β-amyloid peptide (Aβ) in rat hippocampal neurons. Methods: Primary cultures of rat hippocampal neurons were pretreated with liquiritigenin (0.02, 0.2, and 2 μmol/L) prior to Aβ 25-35 exposure. Following treatment, viability of the cells was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analysis and by a lactate dehydrogenase activity-based cytotoxicity assay. Intracellular Ca 2+ concentration ([Ca 2+ ] i ) and levels of reactive oxygen species (ROS), as well as apoptotic rates, were determined. Our studies were extended in tests of whether liquiritigenin treatment could inhibit the secretion of Aβ 1-40 as measured using an ELISA method. In order to analyze which genes may be involved, we used a microarray assay to compare gene expression patterns. Finally, the levels of specific proteins related to neurotrophy and neurodenegeration were detected by Western blotting. Results: Pretreated neurons with liquiritigenin in the presence of Aβ 25-35 increased cell viability in a concentration-dependent manner. Liquiritigenin treatment also attenuated Aβ 25-35 -induced increases in [Ca 2+ ] i and ROS level and decreased the apoptotic rate of neurons. Some genes, including B-cell lymphoma/leukemia-2 (Bcl-2), neurotrophin 3 (Ntf-3) and amyloid β (A4) precursor protein-binding, family B, member 1 (Apbb-1) were regulated by liquiritigenin; similar results were shown at the protein level by Western blotting. Conclusion: Our results demonstrate that liquiritigenin exhibits neuroprotective effects against Aβ 25-35 -induced neurotoxicity and that it can decrease the secretion of Aβ 1-40 . Therefore, liquiritigenin may be useful for further study as a prodrug for treatment of Alzheimer's disease.

Osthole Reverses Beta-Amyloid Peptide Cytotoxicity on Neural Cells by Enhancing Cyclic AMP Response Element-Binding Protein Phosphorylation

“…After 10 d's culture, neurons were exposed to Aβ [25][26][27][28][29][30][31][32][33][34][35] at different concentrations (10,20,30,40 and 50 µM) for 24 h, then MTT assay was used to determine the cell viability. Results showed that Aβ [25][26][27][28][29][30][31][32][33][34][35] insult decreased cell survival in a concentration dependent manner (Fig. 4A), and 30 µM of Aβ [25][26][27][28][29][30][31][32][33][34][35] was the sublethal level, thus was used in the following experiments.…”

“…Osthole Inhibited Aβ-Induced Synapsin-1 Reduction To further investigate the effect of osthole on synaptic proteins, neurons were pre-treated with osthole (50 µM, 24 h) before Aβ [25][26][27][28][29][30][31][32][33][34][35] exposure, and synapsin-1 expression was measured by immunofluorescence and quantitative analysis. As shown in Figs.…”

“…Our data showed that osthole reduced intracellular Aβ levels in neural cells, which was associated with decreased BACE1 protein; osthole reversed exogenous Aβ 25-35 -induced cell viability loss, apoptosis, and synapsin-1 reduction, which was related to the reestablishment of phosphorylation of cyclic AMP response element-binding protein (CREB). The collective evidence indicates that osthole possesses the ability to protect cortical neurons and SH-SY5Y cells against Aβ injury, and the underlying mechanism may be attributed to the enhancement of CREB phosphorylation.Key words osthole; Alzheimer's disease; cyclic AMP response element-binding protein; β-amyloid peptide [25][26][27][28][29][30][31][32][33][34][35] Alzheimer's disease (AD) is an irreversible neurodegenerative disorder of the brain characterized by progressive cognitive loss and memory decline. The abnormal deposition of β-amyloid peptide (Aβ) is one of the most notable neuropathological hallmarks of AD.…”

“…Key words osthole; Alzheimer's disease; cyclic AMP response element-binding protein; β-amyloid peptide [25][26][27][28][29][30][31][32][33][34][35] Alzheimer's disease (AD) is an irreversible neurodegenerative disorder of the brain characterized by progressive cognitive loss and memory decline. The abnormal deposition of β-amyloid peptide (Aβ) is one of the most notable neuropathological hallmarks of AD.…”

“…water and incubated in a 37°C incubator for 7 d to induce aggregation. The aggregated Aβ [25][26][27][28][29][30][31][32][33][34][35] was then diluted to 500 µM and stored at −80°C before use. 22) Cell Viability Assay The MTT assay was carried out as previously described.…”