Resveratrol Attenuates the Disruption of Lipid Metabolism Observed in Amyloid Precursor Protein/Presenilin 1 Mouse Brains and Cultured Primary Neurons Exposed to Aß.

To examine whether resveratrol (RSV), an activator of silent mating-type information regulation 2 homolog 1 (SIRT1), can reverse the disruption of lipid metabolism caused by ß-amyloid peptide (Aß), APP/PS1 mice or cultured primary rat neurons were treated with RSV, suramin (inhibitor of SIRT1), ZLN005, a stimulator of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), or PGC-1α silencing RNA. In the brains of the APP/PS1 mice, expressions of SIRT1, PGC-1α, low-density lipoprotein receptor (LDLR) and very LDLR (VLDLR) were reduced at the protein and, in some cases, mRNA levels; while the levels of the proprotein convertase subtilisin/kexin type 9 (PCSK9), apolipoprotein E (ApoE), total cholesterol and LDL were all elevated. Interestingly, these changes were reversed by administration of RSV, while being aggravated by suramin. Furthermore, activation of PGC-1α, but inhibition of SIRT1, decreased the levels of PCSK9 and ApoE, while increased those of LDLR and VLDLR in the neurons exposed to Aß, and silencing PGC-1α, but activation of SIRT1, did not influence the levels of any of these proteins. These findings indicate that RSV can attenuate the disruption of lipid metabolism observed in the brains of APP mice and in primary neurons exposed to Aß by activating SIRT1, in which the mechanism may involve subsequently affecting PGC-1α.

The influence of NQO2 on the dysfunctional autophagy and oxidative stress induced in the hippocampus of rats and in SH-SY5Y cells by fluoride.

INTRODUCTION: For investigating the mechanism of brain injury caused by chronic fluorosis, this study was designed to determine whether NRH:quinone oxidoreductase 2 (NQO2) can influence autophagic disruption and oxidative stress induced in the central nervous system exposed to a high level of fluoride. METHODS: Sprague-Dawley rats drank tap water containing different concentrations of fluoride for 3 or 6 months. SH-SY5Y cells were either transfected with NQO2 RNA interference or treated with NQO2 inhibitor or activator and at the same time exposed to fluoride. The enrichment of gene signaling pathways related to autophagy was evaluated by Gene Set Enrichment Analysis; expressions of NQO2 and autophagy-related protein 5 (ATG5), LC3-II and p62, and mammalian target of rapamycin (mTOR) were quantified by Western-blotting or fluorescent staining; and the levels of malondialdehyde (MDA) and superoxide dismutase (SOD) assayed biochemically and reactive oxygen species (ROS) detected by flow cytometry. RESULTS: In the hippocampal CA3 region of rats exposed to high fluoride, the morphological characteristics of neurons were altered; the numbers of autophagosomes in the cytoplasm and the levels of NQO2 increased; the level of p-mTOR was decreased, and the levels of ATG5, LC3-II and p62 were elevated; and genes related to autophagy enriched. In vitro, in addition to similar changes in NQO2, p-mTOR, ATG5, LC3 II, and p62, exposure of SH-SY5Y cells to fluoride enhanced MDA and ROS contents and reduced SOD activity. Inhibition of NQO2 with RNAi or an inhibitor attenuated the disturbance of the autophagic flux and enhanced oxidative stress in these cells exposed to high fluoride. CONCLUSION: Our findings indicate that NQO2 may be involved in regulating autophagy and oxidative stress and thereby exerts an impact on brain injury caused by chronic fluorosis.

Mass spectrometry-based metabolomic signatures of coral bleaching under thermal stress.

Coral bleaching caused by climate change has resulted in large-scale coral reef decline worldwide. However, the knowledge of physiological response mechanisms of scleractinian corals under high-temperature stress is still challenging. Here, untargeted mass spectrometry-based metabolomics combining with Global Natural Product Social Molecular Networking (GNPS) was utilized to investigate the physiological response of the coral species Pavona decussata under thermal stress. A wide variety of metabolites (including lipids, fatty acids, amino acids, peptides, osmolytes) were identified as the potential biomarkers and subjected to metabolic pathway enrichment analysis. We discovered that, in the thermal-stressed P. decussata coral holobiont, (1) numerous metabolites in classes of lipids and amino acids significantly decreased, indicating an enhanced lipid hydrolysis and aminolysis that contributed to up-regulation in gluconeogenesis to meet energy demand for basic survival; (2) pantothenate and panthenol, two essential intermediates in tricarboxylic acid (TCA) cycle, were up-regulated, implying enhanced efficiency in energy production; (3) small peptides (e.g., Glu-Leu and Glu-Glu-Glu-Glu) and lyso-platelet-activating factor (lysoPAF) possibly implicated a strengthened coral immune response; (4) the down-regulation of betaine and trimethylamine N-oxide (TMAO), known as osmolyte compounds for maintaining holobiont homeostasis, might be the result of disruption of coral holobiont.

LiCl attenuates impaired learning and memory of APP/PS1 mice, which in mechanism involves α7 nAChRs and Wnt/ß-catenin pathway.

We examined the mechanism by which lithium chloride (LiCl) attenuates the impaired learning capability and memory function of dual-transgenic APP/PS1 mice. Six- or 12-month-old APP/PS1 and wild-type (WT) mice were randomized into four groups, namely WT, WT+Li (100 mg LiCl/kg body weight, gavage once daily), APP/PS1 and APP/PS1+Li. Primary rat hippocampal neurons were exposed to ß-amyloid peptide oligomers (AßOs), LiCl and/or XAV939 (inhibitor of Wnt/ß-catenin) or transfected with small interfering RNA against the ß-catenin gene. In the cerebral zone of APP/PS1 mice, the level of Aß was increased and those of α7 nicotinic acetylcholine receptors (nAChR), phosphor-GSK3ß (ser9), ß-catenin and cyclin D1 (protein and/or mRNA levels) reduced. Two-month treatment with LiCl at ages of 4 or 10 months weakened all of these effects. Similar expression variations were observed for these proteins in primary neurons exposed to AßOs, and these effects were attenuated by LiCl and aggravated by XAV939. Inhibition of ß-catenin expression lowered the level of α7 nAChR protein in these cells. LiCl attenuates the impaired learning capability and memory function of APP/PS1 mice via a mechanism that might involve elevation of the level of α7 nAChR as a result of altered Wnt/ß-catenin signalling.

Integrated transcriptomic and proteomic analysis indicated that neurotoxicity of rats with chronic fluorosis may be in mechanism involved in the changed cholinergic pathway and oxidative stress.

BACKGROUND: To reveal the underling molecular mechanism in brain damage induced by chronic fluorosis, the neurotoxicity and its correlation were investigated by transcriptomics and proteomics. METHODS: Sprague-Dawley rats were treated with fluoride at different concentrations (0, 5, 50 and 100 ppm, prepared by NaF) for 3 months. Spatial learning and memory were evaluated by Morris water maze test; neuronal morphological change in the hippocampus was observed using Nissl staining; and the level of oxidative stress including reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) were detected by biological methods. The high-throughput transcriptome sequencing (RNA-Seq) and tandem mass tag (TMT) proteomic sequencing were performed to detect the expression of differentially expressed genes and proteins, respectively. RESULTS: The results showed that compared with control group, rats exposed to high-dose fluoride exhibited declined abilities of learning and memory, decreased SOD activity and increased ROS and MDA levels, with lighter colored Nissl bodies. A total of 28 important differentially expressed genes (DEGs) were screened out by transcriptomics. Then, functional enrichment analyses showed that upregulated proteins enriched in cellular transport, while downregulated proteins enriched in synapse-related pathways. Thirteen corresponding DEGs and DAPs (cor-DEGs-DAPs) were identified by differential expressions selected with positively correlated genes/proteins, most of which were related to neurodegenerative changes and oxidative stress response. CONCLUSION: These results provide new omics evidence that rats chronically exposed to high-dose fluoride can induce neurotoxicity in the brains through changes in the cholinergic pathway and oxidative stress.

Application value and challenge of traditional Chinese medicine carried by ZIF-8 in the therapy of ischemic stroke.

Stroke is a group of major diseases that cause death or disability in adults, with high incidence and lack of available therapeutic strategies. Although traditional Chinese medicine (TCM) has continuously achieved good effects in the therapy of stroke while there is still not convincing due to the limitation of blood-brain permeability, as well as the individual differences in usage and dosage. With the improvement of nanotechnology, TCM nanopreparation has gradually become a research hotspot in various fields due to its advantages in permeating the blood-brain barrier, targeting delivery, enhancing sustained-release drug delivery, changing the distribution in the body, and improving bioavailability. Zeolitic imidazolate framework-8 (ZIF-8) is an ideal nano-drug delivery system for adsorption, catalysis, and drug loading, which is a biocompatible metal-organic framework framed by 2-methylimidazole and zinc ions. At present, ZIF-8 was wildly used in the treatment of ischemic stroke. However, challenges remain persists for its clinical application, such as preparation technology, detection technology in vivo, targeting specificity, safety and stability, and so forth. Therefore, more efforts need to overcome the above problems to develop the application of TCM nanopreparations in the therapy of ischemia/reperfusion in the future.

Lowered levels of nicotinic acetylcholine receptors and elevated apoptosis in the hippocampus of brains from patients with type 2 diabetes mellitus and db/db mice.

Cognitive impairment caused by diabetes has been gradually recognized. Generally, nicotinic acetylcholine receptors (nAChRs) play an important role in the pathogenesis in dementia disorders including Alzheimer's disease (AD). However, the expression of nAChRs in the brains of type 2 diabetes mellitus (T2DM) is unexplored. This study explored the alterations of nAChRs in the postmortem brains of patients with T2DM and brains of db/db mice. Morris water maze test was used to appraise the ability of spatial learning and memory; Western blotting and RT-qPCR were performed to determine the expressions of target protein and mRNA, respectively; TUNEL was used to detect the apoptosis of neurons. We found that the protein levels of nAChR α7 and α4 subunits were significantly decreased and the apoptosis rates in neurons elevated in the hippocampus of T2DM patients and db/db mice as comparison to controls. Furthermore, the db/db mice exhibited the impaired cognition, the elevated level of pro-apoptotic protein and the reduced level of anti-apoptotic and synaptic proteins. This study shows the lowered level of nAChR α7 and α4 subunits and the elevated apoptosis in the hippocampus of T2DM patients and db/db mice, which might help explain the impaired cognition in T2DM.

The neuroprotective effects of SIRT1 in mice carrying the APP/PS1 double-transgenic mutation and in SH-SY5Y cells over-expressing human APP670/671 may involve elevated levels of α7 nicotinic acetylcholine receptors.

The aim was to determine whether the neuroprotective effect of SIRT1 in Alzheimer's disease (AD), due to inhibition of aggregation of the ß-amyloid peptide (Aß), involves activation of α7 nAChR. In present study, four-month-old APP/PS1 mice were administered resveratrol (RSV) or suramin once daily for two months, following which their spatial learning and memory were assessed using the Morris water maze test. Deposits of Aß in vivo were detected by near-infrared imaging (NIRI) and confocal laser scanning. SH-SY5Y/APPswe cells were treated with RSV, suramin, U0126 or methyllycaconitine (MLA). Levels of proteins and mRNA were determined by Western blotting and qRT-PCR, respectively. The results show that activation of SIRT1 improved their spatial learning and memory and reduced the production and aggregation of Aß in the hippocampus and cerebral cortex; whereas inhibition of SIRT1 had the opposite effects. In addition, activation of SIRT1 increased the levels of both α7 nAChR and αAPP in the brains these animals. Finally, activation of SIRT1 elevated the levels of pERK1/2, while inhibition of ERK1/2 counteracted the increase in α7 nAChR caused by RSV. These findings indicate that neuroprotection by SIRT1 may involve increasing levels of α7 nAChR through activation of the MAPK/ERK1/2 signaling pathway.

Berberine Ameliorates Oxygen-glucose Deprivation/Reperfusion-induced Apoptosis by Inhibiting Endoplasmic Reticulum Stress and Autophagy in PC12 Cells.

This study aimed to elucidate the molecular mechanisms by which berberine protects against cerebral ischemia/reperfusion (I/R) injury. The oxygen-glucose deprivation/reperfusion (OGD/R) PC12 model was established. Cell counting kit-8 (CCK-8) was used to detect the toxicity of berberine and the viability of PC12 cells. Hoechst 33258 staining and flow cytometry were used to observe the nuclear morphology, and changes of apoptosis and reactive oxygen species (ROS), respectively. Western blotting and immunofluorescence assay were employed to detect autophagy-related proteins [microtubule-associated protein 1A/1B-light chain 3 (LC3), P62/SQSTM-1, Beclin-1] and endoplasmic reticulum (ER) stress-related markers [glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), Bcl-2-associated X (Bax) and cleaved caspase-3]. The GFP-RFP-LC3 adenovirus was used to assay the change of autophagic flux. Our results showed that berberine could increase the viability of PC12 cells, decrease the concentrations of ROS after OGD/R treatment, and suppress OGD/R-induced ER stress and autophagy. Moreover, the results revealed the involvement of the mammalian target of rapamycin (mTOR) pathway in the induction of autophagy, and berberine could activate the phosphorylation of mTOR and thus mitigate autophagy. In conclusion, our study suggested that berberine may protect against OGD/R-induced apoptosis by regulating ER stress and autophagy, and it holds promises in the treatment of cerebral I/R injury.

Changed expressions of N-methyl-d-aspartate receptors in the brains of rats and primary neurons exposed to high level of fluoride.

Expressions of N-methyl-d-aspartic acid receptors (NMDARs) in the brains of rats and primary neurons exposed to high fluoride were investigated. Sprague-Dawley rats were divided randomly into a fluorosis group (50ppm fluoride in the drinking water for 6 months) and controls (<0.5ppm fluoride) and the offspring from these rats sacrificed on postnatal days 1, 7, 14, 21 and 28. The primary cultured neurons from the hippocampus of neonatal rats were treated with 5 and 50ppm fluoride for 48h. NMDAR subunits at protein or mRNA levels were quantified by Western blotting or real-time PCR. The phosphorylated calmodulin-protein kinase II (CaMKII) was determined by Western blotting, concentration of Ca2+ in neurons by laser confocal microscopy and apoptosis by flow cytometry. In the brains of adult rats and pups as well as in primary neurons exposed to high fluoride, the mRNAs encoding GluN1 and GluN2B subunits and the corresponding proteins were elevated, the GluN3A lowered and the GluN2A unchanged. In addition, the level of phosphor-CaMKII was reduced, and Ca2+ influx and apoptosis enhanced in the brains of rats and cultured neurons exposed to high fluoride. The results indicate that such modifications may involve brain damage induced by chronic fluorosis.

Serum uric acid levels in patients with Parkinson's disease: A meta-analysis.

BACKGROUND: Lower serum uric acid (UA) levels have been reported as a risk factor in Parkinson's disease (PD). However, the results have been inconsistent so far. OBJECTIVES: The aim of the present study was to clarify the potential relationship of uric acid with PD. METHODS: Comprehensive electronic search in pubmed, web of science, and the Cochrane Library database to find original articles about the association between PD and serum uric acid levels published before Dec 2015. Literature quality assessment was performed with the Newcastle-Ottawa Scale. Random-effects model was used to estimate the standardized mean differences (SMDs) with 95% confidence intervals (CIs). Heterogeneity across studies was assessed using I2 and H2 statistics. Sensitivity analyses to assess the influence of individual studies on the pooled estimate. Publication bias was investigated using funnel plots and Egger's regression test. Analyses were performed by using Review Manager 5.3 and Stata 11.0. RESULTS: Thirteen studies with a total of 4646 participants (2379 PD patients and 2267 controls) were included in this meta-analysis. The current results showed that the serum UA levels in PD patients were significantly lower compared to sex and age-matched healthy controls (SMD: -0.49, 95% CI: [-0.67, -0.30], Z = 5.20, P < 0.001) and these results showed no geographic regional (Asia: SMD = -0.65, 95% CI [-0.84, -0.46], Z = 6.75, p <0.001; Non-Asia: SMD = -0.25, 95% CI [-0.43, -0.07], Z = 2.70, p = 0.007) and sex differences (women: SMD = -0.53, 95% CI [-0.70, -0.35], z = 5.98, p <0.001; men: SMD = -0.66, 95% CI [-0.87, -0.44], z = 6.03, p <0.001). Serum UA levels in middle-late stage PD patients with higher H&Y scales were significantly lower than early stage PD patients with lower H&Y scales (SMD = 0.63, 95% CI [0.36,0.89], z = 4.64, p <0.001). CONCLUSIONS: Our study showed that the serum UA levels are significantly lower in PD and the level is further decreased as the disease progresses. Thus it might be a potential biomarker to indicate the risk and progression of PD.

Elevations in the Levels of NF-κB and Inflammatory Chemotactic Factors in the Brains with Alzheimer's Disease - One Mechanism May Involve α3 Nicotinic Acetylcholine Receptor.

The purpose of this study was to investigate the alterations in the levels of nuclear factor κBp65 (NF-κBp65), monocyte chemoattractant protein 1 (MCP-1/CCL-2) and macrophage inflammatory protein 1α (MIP-1α/CCL-3) in relationship to the expression of α3 nicotinic acetylcholine receptor (nAChR) during the pathogenesis of Alzheimer's disease (AD). The post-mortem human brains of AD and age-matched control individuals, SH-SY5Y and U87MG cell lines exposed to ß-amyloid peptide (Aß), as well as the SH-SY5Y cells in which α3 nAChR was down-regulated by siRNA were used to study the possible expression changes of the targets such as NF-κBp65, MCP-1, MIP-1α and α3 nAChR. The immunohistochemistry results showed the increased immunoreactivities of NF-κBp65, MCP-1 and MIP-1α in neurons in hippocampal and temporal and frontal regions of AD brains. Levels of NF-κBp65, MCP-1 and MIP-1α at both protein and mRNA levels were all significantly up-regulated in SH-SY5Y and U87MG cells exposed to Aß1-42, while expression of α3 nAChRs in Aß1-42 exposed SH-SY5Y cells was attenuated. Interestingly, in the SH-SY5Y cells subjected to α3 nAChR mRNA silencing, expression of NF-κBp65, MCP-1 and MIP-1α was elevated. The elevated expressions of NF- κB and chemokines may be involved by decreased expression of α3 nAChRs during the pathogenesis of AD.

The Diagnostic and Differential Diagnosis Utility of Cerebrospinal Fluid α -Synuclein Levels in Parkinson's Disease: A Meta-Analysis.

Several recent studies showed that α-syn might be a potential diagnostic biomarker for PD in human cerebrospinal fluid (CSF), but the results were inconsistent. The purpose of this meta-analysis was to investigate the diagnostic and differential diagnosis efficacy of CSF α-syn in PD. Studies which measured CSF α-syn or α-syn oligomers in patients with PD and met the inclusion criteria were included in the analysis. Results of the meta-analysis indicated that mean concentration of CSF α-syn was significantly lower in PD compared to controls and significantly higher in PD compared to multiple system atrophy (MSA). No significant difference in mean concentration of CSF α-syn was found between PD and dementia with Lewy bodies (DLB). Mean concentration of CSF α-syn was slightly decreased in PD compared to progressive supranuclear palsy (PSP). Mean concentration of CSF α-syn oligomers was significantly higher in PD than control. These results support the findings that CSF α-syn may be a potential diagnostic and differential diagnosis biomarker in PD compared to control and MSA but not DLB. Furthermore, α-syn oligomer may represent a better biomarker for diagnosis of PD.

Sex-related neurogenesis decrease in hippocampal dentate gyrus with depressive-like behaviors in sigma-1 receptor knockout mice.

Male sigma-1 receptor knockout (σ1R(-/-)) mice showed depressive-like phenotype with deficit in the survival of newly generated neuronal cells in the hippocampal dentate gyrus (DG), but female σ1R(-/-) mice did not. The level of serum estradiol (E2) at proestrus or diestrus did not differ between female σ1R(-/-) mice and wild-type (WT) mice. Ovariectomized (OVX) female σ1R(-/-) mice, but not WT mice, presented the same depressive-like behaviors and neurogenesis decrease as male σ1R(-/-) mice. Treatment of male σ1R(-/-) mice with E2 could alleviate the depressive-like behaviors and rescue the neurogenesis decrease. In addition, E2 could correct the decline in the density of NMDA-activated current (INMDA) in granular cells of DG and the phosphorylation of NMDA receptor (NMDAr) subtype 2B (NR2B) in male σ1R(-/-) mice, which was associated with the elevation of Src phosphorylation. The neuroprotection and antidepressant effects of E2 in male σ1R(-/-) mice were blocked by the inhibitor of Src or NR2B. The NMDAr agonist showed also the neuroprotection and antidepressant effects in male σ1R(-/-) mice, which were insensitive to the Src inhibitor. On the other hand, either the deprivation of E2 or the inhibition of Src in female σ1R(-/-) mice rather than WT mice led to a distinct decline in INMDA and NR2B phosphorylation. Similarly, the Src inhibitor could cause neurogenesis decrease and depressive-like behaviors in female σ1R(-/-) mice, but not in WT mice. These results indicate that the σ1R deficiency impairs neurogenesis leading to a depressive-like phenotype, which is alleviated by the neuroprotection of E2.

The decreased expression of mitofusin-1 and increased fission-1 together with alterations in mitochondrial morphology in the kidney of rats with chronic fluorosis may involve elevated oxidative stress.

This study was designed to characterize changes in the expression of mitofusin-1 (Mfn1) and fission-1 (Fis1), as well as in mitochondrial morphology in the kidney of rats subjected to chronic fluorosis and to elucidate whether any mitochondrial injury observed is associated with increased oxidative stress. Sixty Sprague-Dawley (SD) rats were divided randomly into 3 groups of 20 each, i.e., the untreated control group (natural drinking water containing <0.5mg fluoride/L), the low-fluoride group (drinking water supplemented with 10mg fluoride/L, prepared with NaF) and the high-fluoride group (50mg fluoride/L), and treated for 6 months. Thereafter, renal expression of Mfn1 and Fis1 at both the protein and mRNA levels was determined by immunohistochemistry and real-time PCR, respectively. In addition, the malondiadehyde (MDA) was quantitated by the thiobarbituric acid procedure and the total antioxidative capability (T-AOC) by a colorimetric method. The morphology of renal mitochondria was observed under the transmission electron microscope. In the renal tissues of rats with chronic fluorosis, expression of both Mfn1 protein and mRNA was clearly reduced, whereas that of Fis1 was elevated. The level of MDA was increased and the T-AOC lowered. Swollen or fragmented mitochondria in renal cells were observed under the electronic microscope. These findings indicate that chronic fluorosis can lead to the abnormal mitochondrial dynamics and changed morphology in the rat kidney, which in mechanism might be induced by a high level of oxidative stress in the disease.

Sigma-1 receptor knockout impairs neurogenesis in dentate gyrus of adult hippocampus via down-regulation of NMDA receptors.

AIMS: This study investigated the influence of sigma-1 receptor (σ1 R) deficiency on adult neurogenesis. METHODS: We employed 8-week-old male σ1 R knockout (σ1 R(-/-) ) mice to examine the proliferation and differentiation of progenitor cells, and the survival and neurite growth of newborn neurons in hippocampal dentate gyrus (DG). RESULTS: In comparison with wild-type (WT) littermates, the numbers of 24-h-old BrdU(+) cells and Ki67(+) cells in σ1 R(-/-) mice increased, while the number of 28-day-old BrdU(+) cells decreased without changes in proportion of BrdU(+) /NeuN(+) cells and BrdU(+) /GFAP(+) cells. The neurite density of newborn neurons was slightly reduced in σ1 R(-/-) mice. In DG granular cells, N-methyl-d-aspartate (NMDA)-activated current (INMDA ) and phosphorylation of NMDA receptor (NMDAr) NR2B were reduced in σ1 R(-/-) mice without the alteration of NR2B expression and membrane properties compared to WT mice. The NR2B antagonist abolished the difference in INMDA between σ1 R(-/-) mice and WT mice. The application of NMDAr agonist in σ1 R(-/-) mice prevented the over-proliferation of cells and reduction in newborn neurons, but it had no effects on the hypoplastic neurite. The administration of NMDAr antagonist in WT mice enhanced the cell proliferation and depressed the survival of newborn neurons. CONCLUSION: The σ1 R deficiency impairs neurogenesis in DG through down-regulation of NMDArs.

[Simultaneous resolution and determination of tyrosine, tryptophan and phenylalanine by alternating penalty trilinear decomposition algorithm coupled with 3D emission-excitation matrix fluorometry].

A new method using alternating penalty trilinear decomposition algorithm coupled with excitation-emission matrix fluorometry has been developed for simultaneous resolution and determination of tyrosine, phenylalanine and tryptophan. Their correlation coefficients were 0.9987, 0.9995 and 0.9993 respectively. The contents of tyrosine, phenylalanine and tryptophan in Hibiscus syriacus L. leaves were also be determined by this method after being extracted by ultrasonic. The coefficients of variation and the recoveries of the three amino acids were 0.84%, 0.36%, 1.59% and 101.0%-92.7%, 106.5%-93.0%, 103.0%-95.0% respectively. All these show that this is a simple, fast and cridible method.

Effect of subchronic treatment of memantine, galantamine, and nicotine in the brain of Tg2576 (APPswe) transgenic mice.

An increasing number of studies suggest that the present clinical therapy used in Alzheimer's disease (AD), in addition to having a symptomatic effect, also may interact with the ongoing neuropathological processes in the brain. The aim of this study was to investigate the effect of the cholinesterase inhibitor galantamine and the N-methyl-d-aspartate (NMDA) antagonist memantine in comparison to nicotine on the neuropathology of Tg2576 transgenic mice (APPswe). Nontransgenic and APPswe mice at 10 months of age were treated subcutaneously with saline, memantine, galantamine, or nicotine for 10 days. Nicotine reduced the guanidinium-soluble amyloid-beta peptide (Abeta) levels by 46 to 66%, whereas the intracellular Abeta levels remained unchanged. Treatment with nicotine also resulted in less glial fibrillary acidic protein immunoreactive astrocytes around the plaques, increased levels of synaptophysin, and increased number of alpha7 nicotinic acetylcholine receptors (nAChRs) in the cortex of APPswe transgenic mice. Galantamine treatment caused an increase in the cortical levels of synaptophysin in the APPswe mice. Memantine treatment reduced the total cortical levels of membrane-bound amyloid precursor protein (45-55%) in both transgenic and nontransgenic mice, which eventually may decrease the level of Abeta. In conclusion, galantamine, memantine, and nicotine have different interactions with Abeta processes, alpha7 nAChRs, and NMDA receptors in APPswe mice. These different effects might have therapeutic relevance, and this knowledge might be applicable to the development of new effective therapeutic strategies for AD.

Lovastatin stimulates up-regulation of alpha7 nicotinic receptors in cultured neurons without cholesterol dependency, a mechanism involving production of the alpha-form of secreted amyloid precursor protein.

The cholesterol-lowering drug lovastatin enhances the secretion of the alpha-secretase cleavage product of amyloid precursor protein (APP). To investigate whether this effect is mediated via activation of alpha7 nicotinic acetylcholine receptors (nAChRs), we treated SH-SY5Y cells and PC12 cells with lovastatin and measured the levels of alpha7 nAChRs, the alpha-form of secreted APP (alphaAPPs), and lovastatin-related lipids, including cholesterol and ubiquinone. The results showed that low concentrations of lovastatin significantly induced up-regulation of alpha7 nAChRs. No effects of lovastatin were observed on alpha3-containing nAChRs, muscarinic receptors, or N-methyl-D-aspartate receptors. alphaAPPs levels increased in the culture medium of cells treated with lovastatin, whereas no change in whole APP was observed. The increase in alphaAPPs was inhibited by prior exposure of these cells to alpha-bungarotoxin, an antagonist of alpha7 nAChRs. The concentrations of lovastatin used in the study did not change the cholesterol content, but high doses can decrease the levels of ubiquinone and cell viability. These results indicate that lovastatin may play a neuronal role that is cholesterol independent. We also show that the up-regulation of alpha7 nAChRs stimulated by lovastatin is involved in a mechanism that enhances production of alphaAPPs during APP processing.

High selective expression of alpha7 nicotinic receptors on astrocytes in the brains of patients with sporadic Alzheimer's disease and patients carrying Swedish APP 670/671 mutation: a possible association with neuritic plaques.

In the present study, we have investigated the expression of nicotinic acetylcholine receptors (nAChRs) on astrocytes and neurons in the hippocampus and temporal cortex of subjects carrying the Swedish amyloid precursor protein (APP) 670/671 mutation (APPswe), patients with sporadic Alzheimer's disease (AD), and age-matched control subjects. Significant increases in the total numbers of astrocytes and of astrocytes expressing the alpha7 nAChR subunit, along with significant decreases in the levels of alpha7 and alpha4 nAChR subunits on neurons, were observed in the hippocampus and temporal cortex of both APPswe and sporadic AD brains. Both of these phenomena were more pronounced in APPswe than sporadic AD cases. Furthermore, the number of [(125)I]alpha-BTX binding sites (alpha7 nAChR) in the temporal cortex of the APPswe brain was significant lower than in the younger control group, reflecting the lower neuronal level of alpha7 nAChR. The increase in the level of expression of alpha7 nAChR on astrocytes was positively correlated with the extent of neuropathological alternations, especially the number of neuritic plaques, in the AD brain. The elevated expression of alpha7 nAChR on astrocytes might participate in Abeta cascade and formation of neuritic plaques, thereby playing an important role in the pathogenesis of AD.