The bexarotene derivative OAB-14 ameliorates cognitive decline in APP/PS1 transgenic mice by suppressing microglia-mediated neuroinflammation through the PPAR-γ pathway.

Neuroinflammation is believed to be a critical process involved in the pathophysiology of Alzheimer's disease (AD). In this study, we investigated the pharmacological ability of OAB-14, a small molecule compound derived from bexarotene, to reduce neuroinflammation and improve cognitive decline in an AD mouse model (in vivo) and its ability to regulate signaling pathways implicated in neuroinflammation in vitro. It was found that OAB-14 significantly improved the cognitive function of 11-month-old AD mice (APP/PS1 transgenic mice) in a dose-dependent manner. Simultaneously, OAB-14 dramatically inhibited the activation of microglia in the cerebral cortex and hippocampus of AD mice and dose-dependently downregulated the expression of nuclear factor kappa B (NF-κB) and NOD-like receptor protein 3 (NLRP3) in the cerebral cortex. At the cellular level, OAB-14 reversed the downregulation of M2 phenotypic markers, including mannose receptor C-type 1 (MRC1) and arginase 1 (ARG1), in lipopolysaccharide (LPS)- or amyloid-ß protein oligomer (oAß1-42)-activated BV2 microglial cells and partially restored their ability to clear Aß. However, these effects were suppressed when peroxisome proliferator-activated receptor-γ (PPAR-γ) was specifically inhibited by GW9662, a selective PPAR-γ antagonist. These results suggested that OAB-14 could regulate microglial polarization by regulating PPAR-γ signaling, thereby mitigating neuroinflammation and improving cognitive function in AD mice.

PINK1 overexpression prevents forskolin-induced tau hyperphosphorylation and oxidative stress in a rat model of Alzheimer's disease.

PTEN-induced putative kinase 1 (PINK1)/parkin pathway mediates mitophagy, which is a specialized form of autophagy. Evidence shows that PINK1 can exert protective effects against stress-induced neuronal cell death. In the present study we investigated the effects of PINK1 overexpression on tau hyperphosphorylation, mitochondrial dysfunction and oxidative stress in a specific rat model of tau hyperphosphorylation. We showed that intracerebroventricular (ICV) microinjection of forskolin (FSK, 80 µmol) induced tau hyperphosphorylation in the rat brain and resulted in significant spatial working memory impairments in Y-maze test, accompanied by synaptic dysfunction (reduced expression of synaptic proteins synaptophysin and postsynaptic density protein 95), and neuronal loss in the hippocampus. Adeno-associated virus (AAV)-mediated overexpression of PINK1 prevented ICV-FSK-induced cognition defect and pathological alterations in the hippocampus, whereas PINK1-knockout significantly exacerbated ICV-FSK-induced deteriorated effects. Furthermore, we revealed that AAV-PINK1-mediated overexpression of PINK1 alleviated ICV-FSK-induced tau hyperphosphorylation by restoring the activity of PI3K/Akt/GSK3ß signaling. PINK1 overexpression reversed the abnormal changes in mitochondrial dynamics, defective mitophagy, and decreased ATP levels in the hippocampus. Moreover, PINK1 overexpression activated Nrf2 signaling, thereby increasing the expression of antioxidant proteins and reducing oxidative damage. These results suggest that PINK1 deficiency exacerbates FSK-induced tau pathology, synaptic damage, mitochondrial dysfunction, and antioxidant system defects, which were reversed by PINK1 overexpression. Our data support a critical role of PINK1-mediated mitophagy in controlling mitochondrial quality, tau hyperphosphorylation, and oxidative stress in a rat model of Alzheimer's disease.

Sigma-1 receptor activation alleviates blood-brain barrier dysfunction in vascular dementia mice.

Sigma-1 receptor (Sig-1R) activation has been shown to decrease infarct volume and enhance neuronal survival after brain ischemia-reperfusion (IR) in rodent models. The present study aims to investigate first the effect of Sig-1R activation on blood-brain barrier (BBB) disruption during experimental stroke. Male C57BL/6 mice were subjected to bilateral common carotid artery occlusion (BCCAO) for 15 min, and the worst BBB leakage was observed on the 7th day after brain IR. To confirm the BBB protective role of Sig-1R, mice were divided into five groups (sham group, BCCAO group, PRE084 group, BD1047 group, PRE084 and BD1047 group; 29-35 mice for each group), and treated with agonist PRE084 (1 mg/kg) and/or antagonist BD1047 (1 mg/kg) for 7 days intraperitoneally once a day after BCCAO. Interestingly, PRE084 administration significantly improved neurobehavioral performance as well as healing of neuron damage and white matter lesions. PRE084 also reduced the leakage of Evans blue and IgG and attenuated the disassembly of BBB structural proteins, while the neuroprotective and BBB protective functions of PRE084 were blocked by BD1047. Furthermore, in Sig-1R knockout (Sig-1R KO) mice, brain IR produced more serious IgG leakage and degradation of BBB structural proteins than in wild-type model mice. In addition, the protective effect of PRE084 against the BBB was lost in Sig-1R KO mice after brain IR. Finally, treatment with PRE084 significantly increased the expression of Sig-1R in brain microvascular endothelial cells of mice that were subjected to brain IR and increased translocation of Sig-1R to the cell plasmalemma. Thus, we identified a previously unexplored role of Sig-1R in alleviating BBB disruption in stroke processes and have demonstrated that reversing BBB rupture through Sig-1R activation may be another promising method for cerebral protection against IR injury.

Synthesis, biological evaluation and structure-activity relationship studies of hederacolchiside E and its derivatives as potential anti-Alzheimer agents.

Inspired by the previously reported neuroprotective activity of hederacolchiside E (1), we synthesized hederacolchiside E for the first time along with eleven of its derivatives. The neuroprotective effects of these compounds were further evaluated against H2O2- and Aß1-42-induced injury using cell-based assays. The derivatives showed obvious differences in activity due to structural variations, and two of them exhibited better neuroprotective effects than 1 in the Aß1-42-induced injury model. Compound 7 was the most active derivative and had a relatively simple chemical structure. Moreover, 1 and 7 can significantly reduce the release of lactate dehydrogenase (LDH), level of intracellular reactive oxygen species (ROS) and extent of malondialdehyde (MDA) increase resulting from Aß1-42 treatment, which demonstrated that these kinds of compounds show neuroprotective effects in Alzheimer's disease (AD) models via modulating oxidative stress. Compound 7 could be used as promising lead for the development of a new type of neuroprotective agent against AD.

Xanthoceraside attenuates amyloid ß peptide1-42-induced memory impairments by reducing neuroinflammatory responses in mice.

Xanthoceraside, a novel triterpenoid saponin extracted from the husks of Xanthoceras sorbifolia Bunge, has neuroprotective effects in vivo and anti-inflammatory properties in vitro. However, the exact mechanism of xanthoceraside on anti-amyloid beta (Aß)-induced neuroinflammatory responses has not been elucidated. Therefore, we used intracerebroventricular injection of amyloid 1-42 (Aß1-42) to establish a mouse model to test the effects of xanthoceraside on Aß-induced cognitive impairments and the TLR2/NF-κB and MAPK pathways. The mice received xanthoceraside (0.02, 0.08 or 0.32mg/kg) or vehicle from the day of Aß1-42 injection. The Morris water maze test was performed 4 days after Aß1-42 injection. The levels of inflammatory cytokines (interleukin (IL)-6 and IL-4) were measured by enzyme-linked immunosorbent assay (ELISA). The expression levels of glial fibrillary acidic protein (GFAP) and cluster of differentiation 11b (CD11b) in the hippocampus were determined with an immunohistochemistry assay. Inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) were analysed by Western blotting; iNOS, COX-2 and Toll-like receptor 2 (TLR2) mRNA expression levels were measured by reverse transcription-polymerase chain reaction (RT-PCR). Here, we observed that xanthoceraside at doses of 0.08 and 0.32mg/kg significantly improved learning and memory impairments and significantly inhibited GFAP and CD11b overexpression induced by Aß1-42 in mice. ELISA results revealed that xanthoceraside suppressed IL-6 release and increased IL-4 levels. Western blotting results showed that xanthoceraside reduced iNOS and COX-2 protein levels in hippocampus; xanthoceraside also inhibited translocation of NF-κB p50 and p65 into the nucleus and phosphorylation of extracellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK) and p38. RT-PCR confirmed that xanthoceraside decreased iNOS, COX-2 and TLR2 mRNA levels. These results suggest that xanthoceraside inhibition of the TLR2 pathway and down-regulation of MAPK and NF-κB activities may be related to the improvement in learning and memory impairments.

Sigma-1 receptor in brain ischemia/reperfusion: Possible role in the NR2A-induced pathway to regulate brain-derived neurotrophic factor.

Sigma-1 receptor (σ1r) activation could attenuate the learning and memory deficits in the AD model, ischemia model and others. In our previous study, the activation of σ1r increased the expression of brain-derived neurotrophic factor (BDNF), possibly through the NR2A-induced pathway, and σ1r agonists might function as neuroprotectant agents in vascular dementia. Here, we used σ1r knockout mice to confirm the role of σ1r. Furthermore, an antagonist of NR2A was first used to investigate whether the NR2A-induced pathway is the necessary link between σ1r and BDNF. The operation of brain ischemia/reperfusion was induced by bilateral common carotid artery occlusion for 20min in C57BL/6 and σ1r knockout mice as the ischemic group. A σ1r agonist, PRE084 (1mg/kg, i.p.), and NR2A antagonist, PEAQX (10mg/kg, i.p.), were administered once daily throughout the experiment. Behavioral tests were performed starting on day 8. On day 22 after brain ischemia/reperfusion, mice were sacrificed and brains were immediately collected and the injured and the hippocampus was isolated and stored at -80°C for western blot analysis. After ischemic operation, contrast with the σ1r knockout mice, PRE084 significantly ameliorated learning and memory impairments in the behavioral evaluation, and prevented the protein decline of BDNF, NR2A, CaMKIV and TORC1 expression in wild-type mice. However, the effects of PRE084 on CaMKIV-TORC1-CREB and BDNF, even for learning and memory impairment, were antagonized by the co-administration of PEAQX, an antagonist of NR2A. The activation of σ1r improves the impairment of learning and memory in the ischemia/reperfusion model, and the expression of BDNF, which may have been achieved through the NR2A-CaMKIV-TORC1 pathway.

The total triterpenoid saponins of Xanthoceras sorbifolia improve learning and memory impairments through against oxidative stress and synaptic damage.

BACKGROUND: X. sorbifolia is a widely cultivated ecologicalcrop in the north of China which is used to produce biodiesel fuel. It also possesses special medicinal value and has attracted keen interests of researchers to explore its bioactivity. PURPOSE: To extract the total triterpenoid saponins from the husk of X. sorbifolia (TSX) and investigate its effects on Alzheimer's disease (AD). STUDY DESIGN: TSX was prepared via modern extraction techniques. Its effects on two AD animal models, as well as the preliminary mechanism were investigated comprehensively. METHODS: The behavioral experiments including Y maze test, Morris water maze test and passive avoidance test were performed to observe the learning and memory abilities of the animals. ELISA assays, transmission electron microscope observation and Western blotting were employed in mechanism study. RESULTS: TSX, the main composition of X. sorbifolia, accounted for 88.77% in the plant material. It could significantly increase the spontaneous alternation in Y maze test (F (6, 65)=3.209, P<0.01), prolong the swimming time in the fourth quadrant in probe test of Morris water maze test (F (6, 71)=4.019, P<0.01), and increase the escape latency in passive avoidance test (F (6, 65)=3.684, P<0.01) in AD model animals. The preliminary mechanism research revealed that TSX could significantly increase the contents of hippocampal Ach and ChAT, and enhance activity of ChAT in hippocampus of quinolinic acid injected rats (F (5, 61)=3.915, P 0.01; F (5, 61)=3.623, P<0.01, F (5, 61)=4.344, P<0.01, respectively). It could also increase the activities of T-AOC and T-SOD, and decrease the content of MDA in hippocampus of Aß1-42 injected mice (F (5, 30)=5.193, P<0.01, F (5, 30)=2.865, P<0.05, F (5, 30)=4.735, P<0.01, respectively). Moreover, it significantly increased the expressions of SYP, PSD-95 and GAP-43 in hippocampus (F (4, 27)=3.495, P<0.05; F (4, 27)=2.965, P<0.05; F (4, 27)=4.365, P<0.01, respectively), and improved the synaptic ultra-structure damage in model rats. CONCLUSION: TSX could significantly improve the impairments of learning and memory. The preliminary mechanism might associate with its protection effects against oxidative stress damage, cholinergic system deficiency and synaptic damage. TSX are perfectly suitable for AD patients as medicine or functional food, which would be a new candidate to treat AD.

Sigma 1 receptor activation regulates brain-derived neurotrophic factor through NR2A-CaMKIV-TORC1 pathway to rescue the impairment of learning and memory induced by brain ischaemia/reperfusion.

RATIONALE: Sigma-1 receptor (Sig-1R) agonists showed anti-amnesic properties in Alzheimer's disease models and anti-inflammatory properties in cerebrum ischaemia models. The agonist of Sig-1R was reported to up-regulate brain-derived neurotrophic factor (BDNF) levels in the hippocampus of mice. Here, we investigate whether the activation of Sig-1R attenuates the learning and memory impairment induced by ischaemia/reperfusion and how it affects the expression of BDNF. OBJECTIVES: Bilateral common carotid artery occlusion (BCCAO) was induced for 20 min in C57BL/6 mice. MATERIALS AND METHODS: Sig-1R agonist, PRE084, sigma 1/2 non-selective agonist, DTG, Sig-1R antagonist and BD1047 were injected once daily throughout the experiment. Behavioural tests were performed from day 8. On day 22 after BCCAO, mice were sacrificed for biochemical analysis. RESULTS: PRE084 and DTG ameliorated learning and memory impairments in the Y maze, novel object recognition, and water maze tasks and prevented the decline of synaptic proteins and BDNF expression in the hippocampus of BCCAO mice. Furthermore, PRE084 and DTG up-regulated the level of NMDA receptor 2A (NR2A), calcium/calmodulin-dependent protein kinase type IV (CaMKIV) and CREB-specific co-activator transducer of regulated CREB activity 1 (TORC1). Additionally, the effects of PRE084 and DTG were antagonised by the co-administration of BD1047. CONCLUSIONS: Sig-1R activation showed an attenuation in the ischaemia/reperfusion model and the activation of Sig-1R increased the expression of BDNF, possibly through the NR2A-CaMKIV-TORC1 pathway, and Sig-1R agonists might function as neuroprotectant agents in vascular dementia.

Xanthoceraside ameliorates mitochondrial dysfunction contributing to the improvement of learning and memory impairment in mice with intracerebroventricular injection of aß1-42.

The effects of xanthoceraside on learning and memory impairment were investigated and the possible mechanism associated with the protection of mitochondria was also preliminarily explored in Alzheimer's disease (AD) mice model induced by intracerebroventricular (i.c.v.) injection of Aß1-42. The results indicated that xanthoceraside (0.08-0.32 mg/kg) significantly improved learning and memory impairment in Morris water maze test and Y-maze test. Xanthoceraside significantly reversed the aberrant decrease of ATP levels and attenuated the abnormal increase of ROS levels both in the cerebral cortex and hippocampus in mice injected with Aß1-42. Moreover, xanthoceraside dose dependently reversed the decrease of COX, PDHC, and KGDHC activity in isolated cerebral cortex mitochondria of the mice compared with Aß1-42 injected model mice. In conclusion, xanthoceraside could improve learning and memory impairment, promote the function of mitochondria, decrease the production of ROS, and inhibit oxidative stress. The improvement effects on mitochondria may be through withstanding the damage of Aß to mitochondrial respiratory chain and the key enzymes in Kreb's cycle. Therefore, the results from present study and previous study indicate that xanthoceraside could be a competitive candidate for the treatment of AD.

Xanthoceraside rescues learning and memory deficits through attenuating beta-amyloid deposition and tau hyperphosphorylation in APP mice.

Xanthoceraside, a triterpenoid saponin, has been shown to reverse cognitive deficits in several Alzheimer's disease (AD) animal models. However, the effects of xanthoceraside on the Aß deposition pathology and the APP processing in AD are unclear. Here, we show that xanthoceraside at doses of 0.08 and 0.32 mg/kg/d for 6 months significantly improved learning and memory impairment in APP transgenic mice assessed by the Y maze and novel object recognition tests. Immunohistochemical analyses revealed that xanthoceraside strongly attenuated ß-amyloid deposition in the brains of APP transgenic mice. Western blotting revealed that xanthoceraside decreased tau phosphorylation protein levels at Ser396 and Ser404 in the hippocampus; xanthoceraside also decreased APP protein levels and GSK-3ß phosphorylation. These results suggest that xanthoceraside could be a promising novel candidate for the therapy of AD.

Xanthoceraside attenuates tau hyperphosphorylation and cognitive deficits in intracerebroventricular-streptozotocin injected rats.

RATIONALE: Xanthoceraside, a novel triterpenoid saponin extracted from the fruit husks of Xanthoceras sorbifolia Bunge, reverses cognitive deficits in intracerebroventricular injection of Aß25-35 or Aß1-42 mice. However, whether xanthoceraside has a positive effect on hyperphosphorylated tau protein remains unclear. OBJECTIVES: We investigated the effects of xanthoceraside on behavioural impairments induced by intracerebroventricular injection of streptozotocin (STZ) in rats and its potential mechanisms. MATERIALS AND METHODS: The rats were administered with xanthoceraside (0.06, 0.12 or 0.24 mg/kg) or vehicle once daily after STZ intracerebroventricular injections. The Y-maze test and novel object recognition test were performed 21 and 22 days after the second STZ injection, respectively. The levels of hyperphosphorylated tau, phosphatidylinositol-3-kinase (PI3K)/serine/threonine protein kinase B (Akt), glycogen synthase kinase-3ß (GSK-3ß), protein phosphatase 1 (PP-1) and protein phosphatase 2A (PP-2A) were also tested by Western blot. RESULTS: Xanthoceraside treatment significantly attenuated learning and memory impairments and reduced the level of STZ-induced hyperphosphorylated tau protein. Xanthoceraside also enhanced PP-2A and PP-1 expressions, increased PI3K (p85) and Akt (Ser473) phosphorylation and decreased GSK-3ß (tyr216) phosphorylation. CONCLUSIONS: Xanthoceraside has protective effect against learning and memory impairments and inhibits tau hyperphosphorylation in the hippocampus, possibly through the inhibition of the PI3K/Akt-dependent GSK-3ß signalling pathway and an enhancement of phosphatases activity.

Protective effect of xanthoceraside against ß-amyloid-induced neurotoxicity in neuroblastoma SH-SY5Y cells.

ß-Amyloid (Aß)-induced neurotoxicity is a major pathological mechanism of Alzheimer's disease (AD). Xanthoceraside, a triterpene extracted from the husk of Xanthoceras sorbifolia Bunge, has been shown to have therapeutic effects on learning and memory impairment induced by Aß intracerebroventricular infusion in mice. In this study, we investigated the effect of xanthoceraside on the neurotoxicity of Aß25-35 in SH-SY5Y cells. Cell viability was measured by MTT (3-(3,4-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) assay. Cell apoptosis, reactive oxygen species (ROS) generation, and mitochondrion membrane potential (MMP) were measured using Annexin V/propidium iodide, 2,7-dichlorofluorescein diacetate, and rhodamine 123 with flow cytometry, respectively. Intracellular calcium level was determined with Fura-2/AM. Caspase-3 activity in cell lysates was measured using the spectrophotometric method. Results indicated that pretreatment with xanthoceraside (0.01 and 0.1 µM) obviously increased the viability of SH-SY5Y cells injured by Aß25-35 in a dose-dependent manner. Aß25-35-induced early apoptosis, ROS overproduction, MMP dissipation, intracellular calcium overload, and increase in caspase-3 activity were markedly reversed by xanthoceraside. These findings suggested that xanthoceraside might be useful in the prevention and treatment of AD.

Xanthoceraside inhibits pro-inflammatory cytokine expression in Aß25-35/IFN-γ-stimulated microglia through the TLR2 receptor, MyD88, nuclear factor-κB, and mitogen-activated protein kinase signaling pathways.

An accumulating body of evidence suggests that Alzheimer's disease (AD) is associated with microglia-mediated neuroinflammation and pro-inflammatory cytokine expression. Therefore, the suppression of neuroinflammation and pro-inflammatory cytokine might theoretically slow down the progression of AD. Xanthoceraside, a novel triterpenoid saponin extracted from the husks of Xanthoceras sorbifolia Bunge, has potent antiinflammatory and neuroprotective effects. However, the molecular mechanism underlying its anti-inflammatory action remains unclear. In the present study, we attempted to determine the effects of xanthoceraside on the production of pro-inflammatory mediators in amyloid ß25-35 (Aß25-35)/interferon-γ (IFN-γ)-stimulated microglia. Our results indicated that xanthoceraside (0.01 and 0.1 µM) significantly inhibited the release of nitric oxide (NO) and pro-inflammatory cytokines interleukin-1ß and tumor necrosis factor-α in a concentration-dependent manner. Reverse transcriptase-polymerase chain reaction and western blotting analyses showed that xanthoceraside decreased the Aß25-35/IFN-γ-induced production of cyclooxygenase-2 and inducible NO synthase. These effects were accompanied by inhibited activities of nuclear factor-κB and mitogen-activated protein kinase through Toll-like receptor 2 in a myeloid differentiation protein 88-dependent manner. Our results provide support for the therapeutic potential of xanthoceraside in AD.

Steroidal glycosides from Reineckia carnea herba and their antitussive activity.

Two new steroidal glycosides, 1α,3α-dihydroxy-5ß-pregn-16-en-20-one 3-O-α-L-rhamnopyranoside (1) and 1ß,3ß,27-trihydroxycholest-16-en-22-one 1,3-di-O-α-L-rhamnoside (2), along with seven known steroidal glycosides (3-9), were isolated from Reineckia carnea herba. Their structures were determined by detailed analysis of their 1D- and 2D-NMR and MS spectra. Compound 9 was isolated for the first time from the Reineckia genus. Except for 8, compounds 2, 3, 4, 5, 6, 7, and 9 displayed clear in vitro antitussive activity.

Aquaporin-1 plays a crucial role in estrogen-induced tubulogenesis of vascular endothelial cells.

CONTEXT: Aquaporin-1 (AQP1) has been proposed as a mediator of estrogen-induced angiogenesis in human breast cancer and endometrial cancer. Elucidation of the molecular mechanisms governing AQP1-mediated, estrogen-induced angiogenesis may contribute to an improved understanding of tumor development. OBJECTIVE: Our objective was to identify the estrogen-response element (ERE) in the promoter of the Aqp1 gene and investigate the effects and mechanisms of AQP1 on estrogen-induced tubulogenesis of vascular endothelial cells. SETTING: The study was conducted in a university hospital in eastern China. MAIN OUTCOME MEASURES: Immunohistological, real-time PCR and Western blot analyses were used to determine the expression AQP1 mRNA and protein in vascular endothelial cells. Chromatin immunoprecipitation analyses and luciferase reporter assays identified ERE-like motif in the promoter of the Aqp1 gene. RESULTS: Expression of AQP1 in blood vessels of human breast and endometrial carcinoma tissues were significantly higher than controls. Estradiol (E2) dose-dependently increased the expression levels of AQP1 mRNA and protein in human umbilical vein endothelial cells (HUVECs). A functional ERE-like motif was identified in the promoter of the Aqp1 gene. AQP1 colocalized with ezrin, a component of the ezrin/radixin/moesin protein complex, and, ezrin colocalized with filamentous actin in HUVECs. Knockdown of AQP1 or ezrin with specific small interfering RNA significantly attenuated the formation of transcytoplasmic filamentous actin stress fibers induced by E2 and inhibited E2-enhanced cell proliferation, migration, invasion, and tubule formation of HUVECs. CONCLUSIONS: Estrogen induces AQP1 expression by activating ERE in the promoter of the Aqp1 gene, resulting in tubulogenesis of vascular endothelial cells. These results provide new insights into the molecular mechanisms underpinning the angiogenic effects of estrogen.

Saponins with neuroprotective effects from the roots of Pulsatilla cernua.

Four new oleanene-type triterpenoid saponins together with six known saponins were isolated from the roots of Pulsatilla cernua and their structures were elucidated on the basis of spectroscopic data, including 2D NMR spectra and chemical evidence. Among these one of the aglycones (gypsogenin) is reported for the first time from this genus. Some of these compounds showed significant neuroprotective effects against the cytotoxicity induced by ß-amyloid(25-35) (Aß(25-35)) on human neuroblastoma SH-SY5Y cells.

Functional expression of large-conductance calcium-activated potassium channels in human endometrium: a novel mechanism involved in endometrial receptivity and embryo implantation.

BACKGROUND: Large-conductance calcium-activated potassium channels (BK(Ca) channels) mediate physiological processes in nonexcitable cells. OBJECTIVE: The aim of the study was to determine BK(Ca) channel expression in human endometrium and its role in endometrial receptivity and embryo implantation. METHODS: BK(Ca) channel expression in human endometrium is described at different phases of the menstrual cycle using quantitative real time-PCR and Western blot techniques. Their effects on embryo implantation were examined using JAr spheroid attachment assays and in vivo mouse model. We examined their effects on endometrial receptivity factors, nuclear factor-κB (NF-κB) activity using quantitative real time-PCR, Western blot, and EMSA analyses. Changes in electrophysiological properties and cytosolic free Ca(2+) were measured in endometrial cells with or without specific BK(Ca) blocker or transfected with BK(Ca) small interfering RNA using patch-clamp and fluorescence analyses, respectively. RESULTS: BK(Ca) channels are expressed in human endometrial cells in a phase-related fashion during the menstrual cycle (proliferative, 0.20 ± 0.02, vs. mid-secretory, 0.72 ± 0.07; P < 0.01). Blocking BK(Ca) channel function or knockdown of endogenous BK(Ca) channel expression not only decreased JAr spheroid attachment rate and embryo implantation rate in mice but also significantly reduced the expression levels of endometrial receptive factors, including leukemia inhibitory factor, integrin ß3, claudin-4, and DKK-1, in human endometrial cells. Blocking BK(Ca) channels also reduced BK(Ca)-regulated NF-κB activity, cytosolic Ca(2+) concentrations, and membrane potentials in human endometrial cells. CONCLUSIONS: These observations demonstrate that BK(Ca) channels: 1) are expressed in endometrial cells; 2) affect embryo implantation by mediating endometrial receptive factors; and 3) alter the activity of NF-κB and homeostasis of Ca(2+) in the human endometrial cells.

Xanthoceraside attenuates amyloid ß peptide25₋35-induced learning and memory impairments in mice.

RATIONALE: In Alzheimer's disease (AD), the deposition of amyloid peptides is invariably associated with oxidative stress and inflammatory responses. Xanthoceraside has anti-inflammatory and antioxidative activities. However, it remains unclear whether xanthoceraside improves amyloid ß (Aß)-induced neurotoxicity. OBJECTIVES: The purpose of this study was to examine the effect of xanthoceraside on behavioral impairments, inflammatory responses, and oxidative stress induced by Aß peptide(25-35) (Aß(25-35)) in mice. MATERIALS AND METHODS: The mice were treated orally with xanthoceraside (0.02, 0.08, or 0.32 mg/kg, once daily) after the intracerebroventricular injection of Aß(25-35) (day 0). Cognitive functions were evaluated in Y-maze (day 6) and novel object recognition tests (days 7 and 8). Inducible nitric oxide synthase (iNOS) and nitrotyrosine levels in the hippocampus were examined (day 9). The mRNA expressions of iNOS and interleukin-4 (IL-4) in the hippocampus were measured 2 h and 3 days after the Aß(25-35) injection by real-time reverse transcription-polymerase chain reaction. RESULTS: Xanthoceraside significantly attenuated behavioral impairments induced by Aß(25-35) in the Y-maze and novel object recognition tests. Repeated treatment with xanthoceraside significantly inhibited the increase in the expression of iNOS and nitrotyrosine in the hippocampus induced by Aß(25-35), which is associated with an enhanced expression of the IL-4 mRNA. CONCLUSIONS: These findings suggest that xanthoceraside attenuates memory impairments through amelioration of oxidative stress and inflammatory responses induced by Aß(25-35) and is a potential candidate for an AD treatment.

Liquiritigenin attenuates the learning and memory deficits in an amyloid protein precursor transgenic mouse model and the underlying mechanisms.

The present paper is to examine whether liquiritigenin is able to attenuate the Alzheimer's-like learning and memory deficits in a transgenic (Tg) mouse model that over-expresses amyloid protein precursor (APP), and explores the underlying mechanisms. Consistent with our previous observations, we found that treatment with liquiritigenin improved the behavioral performance of Tg mice and it attenuated the protein expression of oligomeric form of amyloid ß-peptide (Aß). Furthermore, treatment with liquiritigenin inhibited astrocytosis in the hippocampus, and it may through its inhibitory activities on Notch-2, an important molecular regulating neural proliferation and differentiation. These findings provide evidence for beneficial activity of liquiritigenin in a mouse model of Alzheimer's disease and support the continued investigation of Notch signaling pathway as a target for treatment of Alzheimer's disease.

Identification of estrogen response element in the aquaporin-2 gene that mediates estrogen-induced cell migration and invasion in human endometrial carcinoma.

BACKGROUND: Accumulating evidence suggests that aquaporins (AQP) can facilitate cell migration, invasion, and proliferation in tumor development in addition to water transport. OBJECTIVE: The aim of this study was to examine AQP2 expression in the endometrial tissues from patients with endometrial carcinoma (EC) and determine the roles and mechanisms of AQP2 in estrogen-related cell migration, invasion, adhesion, and proliferation of Ishikawa (IK) cells. APPROACH: AQP2 expression levels were measured in human endometrial cells and estradiol (E(2))-treated IK cells, and the estrogen-response element was identified. After blocking down and up-regulating the endogenous expression of AQP2 in IK cells, cell morphology, capacity for invasion, migration and adhesion, and expression markers of membrane/cytoskeleton were analyzed. RESULTS: AQP2 was expressed in endometrial tissues from patients with EC and endometriosis, both of which are estrogen-dependent diseases. In IK cells, E(2) dose-dependently increased AQP2 expression, which was blocked by the estrogen receptor inhibitor ICI182780. An estrogen-response element was identified in the AQP2 promoter. E(2) significantly increased the migration, invasion, adhesion, and proliferation of IK cells. AQP2 knockdown attenuated E(2)-enhanced migration, invasion, and adhesion. AQP2 knockdown reduced not only the E(2)-enhanced expression of F-actin and annexin-2 but also the E(2)-induced alteration of cell morphology. Moreover, higher expression levels of F-actin and annexin-2 were detected in the endometrial tissues from patients with EC. CONCLUSIONS: AQP2 mediates E(2)-enhanced migration, invasion, and adhesion through alteration of F-actin and annexin-2 expression and reorganization of F-actin, and inhibition of AQP may be a potential method for antitumor therapy.