Alterations in Neuronal Nicotinic Acetylcholine Receptors in the Pathogenesis of Various Cognitive Impairments.

Cognitive impairment is a typical symptom of both neurodegenerative and certain other diseases. In connection with these different pathologies, the etiology and neurological and metabolic changes associated with cognitive impairment must differ. Until these characteristics and differences are understood in greater detail, pharmacological treatment of the different forms of cognitive impairment remains suboptimal. Neurotransmitter receptors, including neuronal nicotinic acetylcholine receptors (nAChRs), dopamine receptors, and glutamine receptors, play key roles in the functions and metabolisms of the brain. Among these, the role of nAChRs in the development of cognitive impairment has attracted more and more attention. The present review summarizes what is presently known concerning the structure, distribution, metabolism, and function of nAChRs, as well as their involvement in major cognitive disorders such as Alzheimer's disease, Parkinson's disease, vascular dementia, schizophrenia, and diabetes mellitus. As will be discussed, the relevant scientific literature reveals clearly that the α4ß2 and α7 nAChR subtypes and/or subunits of the receptors play major roles in maintaining cognitive function and in neuroprotection of the brain. Accordingly, focusing on these as targets of drug therapy can be expected to lead to breakthroughs in the treatment of cognitive disorders such as AD and schizophrenia.

Regulating effect of miR-132-3p on the changes of MAPK pathway in rat brains and SH-SY5Y cells exposed to excessive fluoride by targeting expression of MAPK1.

BACKGROUND: Although the changes of mitogen-activated protein kinase (MAPK) pathway in the central nervous system (CNS) induced by excessive fluoride has been confirmed by our previous findings, the underlying mechanism(s) of the action remains unclear. Here, we investigate the possibility that microRNAs (miRNAs) are involved in the aspect. METHODS: As a model of chronic fluorosis, SD rats received different concentrations of fluoride in their drinking water for 3 or 6 months and SH-SY5Y cells were exposed to fluoride. Literature reviews and bioinformatics analyses were used to predict and real-time PCR to measure the expression of 12 miRNAs; an algorithm-based approach was applied to identify multiply potential target-genes and pathways; the dual-luciferase reporter system to detect the association of miR-132-3p with MAPK1; and fluorescence in situ hybridization to detect miR-132-3p localization. The miR-132-3p inhibitor or mimics or MAPK1 silencing RNA were transfected into cultured cells. Expression of protein components of the MAPK pathway was assessed by immunofluorescence or Western blotting. RESULTS: In the rat hippocampus exposed with high fluoride, ten miRNAs were down-regulated and two up-regulated. Among these, miR-132-3p expression was down-regulated to the greatest extent and MAPK1 level (selected from the 220 genes predicted) was corelated with the alteration of miR-132-3p. Furthermore, miR-132-3p level was declined, whereas the protein levels MAPK pathway components were increased in the rat brains and SH-SY5Y cells exposed to high fluoride. MiR-132-3p up-regulated MAPK1 by binding directly to its 3'-untranslated region. Obviously, miR-132-3p mimics or MAPK1 silencing RNA attenuated the elevated expressions of the proteins components of the MAPK pathway induced by fluorosis in SH-SY5Y cells, whereas an inhibitor of miR-132-3p just played the opposite effect. CONCLUSION: MiR-132-3p appears to modulate the changes of MAPK signaling pathway in the CNS associated with chronic fluorosis.

Periploca forrestii Schltr. ameliorate liver injury caused by fluorosis in rat.

To investigate the impact of the ethanoic fractions of Periploca forrestii Schltr. (P. forrestii) in ameliorating the liver injury caused by fluoride ingestion and to explore the potential mechanisms. Initially, an in vitro fluorosis cell model was constructed using the human normal liver cell line (L-02) induced by fluoride. Cell viability was assessed using the CCK-8 assay kit. The lactate dehydrogenase (LDH) assay kit was utilized to measure LDH content in the cell supernatant, while the malonic dialdehyde (MDA) assay kit was employed to determine MDA levels within the cells. Subsequently, a fluorosis rat model was established, and LDH content in the cell supernatant was measured using the LDH assay kit. Various parameters, including MDA, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and reactive oxygen species (ROS) content within the cells, were detected using appropriate assay kits. Additionally, cell apoptosis rate was determined using the Annexin V-FITC/PI cell apoptosis assay kit. The protein expression levels of B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), Caspase-3, Cleaved Caspase-3, Caspase-9, and Cleaved Caspase-9 were analyzed through Western blotting. Compared to the model group, the ethanolic fraction D of P.forrestii (Fr.D) increased cell viability (P < 0.01) and decreased LDH and MDA levels (P < 0.01). In the high-dose Fr.D treatment group of fluoride-poisoned rats, serum ALT, AST, LDH and MDA levels significantly decreased (P < 0.01). Results from rat primary cells exhibited that the Fr.D administration group exhibited significantly higher cell survival rates than the fluoride group (P < 0.01). Similarly, primary rat cells treated with Fr.D showed enhanced cell viability (P < 0.05) and reduced apoptosis rate, LDH, MDA, SOD, GSH-Px, CAT, and ROS levels (P < 0.05) compared to the model group. Western blot analysis indicated that the Fr.D treatment group elevated the Bcl-2/Bax protein expression ratio and reduced Caspase-3 and Caspase-9 activation levels (P < 0.01) compared to the model group. The results suggest that components within the Fr.D from Periploca forrestii may alleviate fluoride-induced liver injury by potentially counteracting oxidative stress and cell apoptosis.

Exposure to fluoride exacerbates the cognitive deficit of diabetic patients living in areas with endemic fluorosis, as well as of rats with type 2 diabetes induced by streptozotocin via a mechanism that may involve excessive activation of the poly(ADP ribose) polymerase-1/P53 pathway.

Epidemiology has shown that fluoride exposure is associated with the occurrence of diabetes. However, whether fluoride affects diabetic encephalopathy is unclear. Elderly diabetic patients in areas with endemic (n = 169) or no fluorosis (108) and controls (85) underwent Montreal Cognitive Assessment. Sprague-Dawley rats receiving streptozotocin and/or different fluoride doses were examined for spatial learning and memory, brain morphology, blood-brain barrier, fasting blood glucose and insulin. Cultured SH-SY5Y cells were treated with 50 mM glucose and/or low- or high-dose fluoride, and P53-knockdown or poly-ADP-ribose polymerase-1 (PARP-1) inhibition. The levels of PARP-1, P53, poly-ADP-ribose (PAR), apoptosis-inducing factor (AIF), and phosphorylated-histone H2A.X (ser139) were measured by Western blotting. Reactive oxygen species (ROS), 8-hydroxydeguanosine (8-OHdG), PARP-1 activity, acetyl-P53, nicotinamide adenine dinucleotide (NAD+), activities of mitochondrial hexokinase1 (HK1) and citrate synthase (CS), mitochondrial membrane potential and apoptosis were assessed biochemically. Cognition of diabetic patients in endemic fluorosis areas was poorer than in other regions. In diabetic rats, fasting blood glucose, insulin resistance and blood-brain barrier permeability were elevated, while spatial learning and memory and Nissl body numbers in neurons declined. In these animals, expression and activity of P53 and PARP-1 and levels of NAD+, PAR, ROS, 8-OHdG, p-histone H2A.X (ser139), AIF and apoptosis content increased; whereas mitochondrial HK1 and CS activities and membrane potential decreased. SH-SY5Y cells exposed to glucose exhibited changes identical to diabetic rats. The changes in diabetic rats and cells treated with glucose were aggravated by fluoride. P53-knockout or PARP-1 inhibition mitigated the effects of glucose with/without low-dose fluoride. Elevation of diabetic encephalopathy was induced by exposure to fluoride and the underlying mechanism may involve overactivation of the PARP-1/P53 pathway.

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.

Extract of Ginkgo biloba leaves attenuates neurotoxic damages in rats and SH-SY5Y cells exposed to a high level of fluoride.

BACKGROUND: Potential protection against the neurotoxic damages of high levels of fluoride on rats and SH-SY5Y cells by extract of Ginkgo biloba leaves, as well as underlying mechanisms, were examined. METHODS: The rats were divided randomly into 4 groups, i.e., control, treatment with the extract (100 mg/kg body weight, gavage once daily), treatment with fluoride (50 ppm F- in drinking water) and combined treatment with both; SH-SY5Y cells exposed to fluoride and fluoride in combination with the extract or 4-Amino-1,8-naphthalimide (4-ANI), an inhibitor of poly (ADP-ribose) polymerase-1 (PARP-1). Spatial learning and memory in the rats were assessed employing Morris water maze test; the contents of fluoride in brains and urine by fluoride ion-selective electrode; cytotoxicity of fluoride was by CCK-8 kit; the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and the content of malondialdehyde (MDA) by appropriate kits; the level of 8-hydroxydeoxyguanosine (8-OHdG) was by ELISA; the content of ROS and frequency of apoptosis by flow cytometry; the expressions of phospho-histone H2A.X(Ser139), PARP-1, poly (ADP-ribose) (PAR) and Sirtuin-1 (SIRT1) by Western blotting or immunofluorescence. RESULTS: The rats with prolong treatment of fluoride exhibited dental fluorosis, the increased contents of fluoride in brains and urine and the declined ability of learning and memory. In the hippocampus of the rats and SH-SY5Y cells exposed to fluoride, the levels of ROS, MDA, apoptosis, 8-OHdG and the protein expressions of histone H2A.X(Ser139), PARP-1 and PAR were all elevated; the activities of SOD and GSH-Px and the protein expression of SIRT1 reduced. Interestingly, the treatment of Ginkgo biloba extract attenuated these neurotoxic effects on rats and SH-SY5Y cells exposed to fluoride and the treatment of 4-ANI produced a neuroprotective effect against fluoride exposure. CONCLUSION: Ginkgo biloba extract attenuated neurotoxic damages induced by fluoride exposure to rats and SH-SY5Y cells and the underlying mechanism might involve the inhibition of PARP-1 and the promotion of SIRT1.

Activation of α7 Nicotinic Acetylcholine Receptor by its Selective Agonist Improved Learning and Memory of Amyloid Precursor Protein/Presenilin 1 (APP/PS1) Mice via the Nrf2/HO-1 Pathway.

BACKGROUND To reveal the mechanism underlying the effect of alpha7 nicotinic acetylcholine receptor (nAChR) on neurodegeneration in Alzheimer disease (AD), the influence of the receptor on recognition in APP/PS1 mice was evaluated by using its selective agonist (PNU-282987). MATERIAL AND METHODS APP/PS1 and wild-type (WT) mice were treated with PNU or saline, respectively, for 7 days at the ages of 6 and 10 months. RESULTS Morris water maze analysis showed that both at 6 and 10 months of age, PNU treatment enhanced the learning and memory of APP/PS1 mice. However, PNU treatment did not alter the number of senile plaques. Furthermore, a higher protein expression of Nrf2/HO-1, ADAM10, SYP, and SNAP-25, and a lower level of oxidative stress, were observed in the hippocampus of APP/PS1 mice treated with PNU compared with the control group. CONCLUSIONS The results indicated that the activation of alpha7 nAChR by PNU improved the learning and memory of mice carrying the APP/PS1 mutation, regulated the levels of enzymes that mediate APP metabolization to reduce ß-amyloid peptide damage, and decreased the level of oxidative stress and maintained synaptic plasticity, in which the mechanism might be enhancement of the Nrf2/HO-1 pathway.

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.

An inexpensive anaerobic chamber for the genetic manipulation of strictly anaerobic bacteria.

Strictly anaerobic bacteria are important to both human health and industrial usage. These bacteria are sensitive to oxygen, therefore, it is preferable to manipulate these microbes in an anaerobic chamber. However, commercial anaerobic chambers (CACs) are expensive, making them less accessible to scientists with a limited budget, especially to those in developing countries. The high price of commercial chambers has hindered, at least partially, the progress of research on anaerobes in developing countries. In the research presented here, we developed an inexpensive and reliable anaerobic chamber and successfully achieved routine maintenance of eleven strictly anaerobic bacterial strains. Furthermore, genetic manipulation examples have been set for both Clostridioidesdifficile 630 and Clostridiumbeijerinckii NCIMB 8052 strains to validate that the chamber could applied to advanced genetic engineering of strictly anaerobes. C. difficile and C. beijerinckii were both genetically manipulated in this chamber, showing it's utility for the genetic engineering of anaerobes. Most importantly, the anaerobic chamber was 76% - 88% less expensive than a CACs and has similar functionality with regards to the cultivation and manipulation of strictly anaerobic bacteria. The anaerobic chamber described in this study will promote the research of anaerobes in developing counties and scientists who have limited research budgets.

Mangiferin prevents the impairment of mitochondrial dynamics and an increase in oxidative stress caused by excessive fluoride in SH-SY5Y cells.

Previous studies both invivo and in vitro have revealed that high levels of fluoride cause neurotoxicity. Mangiferin has been reported to possess antioxidant, antiapoptotic, and anti-inflammatory properties. The present study was designed to characterize the mechanisms by which mangiferin protects against NaF-induced neurotoxicity. Increased levels of proapoptotic Bax, Caspase-3, Caspase-9, and cleaved-caspase 3, as well as a decreased level of antiapoptotic Bcl-2 induced by fluoride in human neuroblastoma SH-SY5Y cells, these effects were prevented by pretreatment of mangiferin. In addition, mangiferin attenuated the enhancement of p-JNK, reductions of Nrf2 and HO-1, and increased level of the mitochondrial fission proteins Drp1 caused by fluoride. Moreover, oxidative stress, as reflected in the levels of reactive oxygen species, 8-hydroxy-2'-deoxyguanosine, and 4-hydroxynonenal, was elevated by fluoride and these effects were again ameliorated by mangiferin. In conclusion, protection by mangiferin against fluoride-induced neurotoxicity involves normalizing the impaired mitochondrial apoptotic pathway and dynamics and reducing oxidative stress via inactivation of the JNK and activation of the Nrf2/HO-1 pathways.

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.

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.

Expression levels of the α7 nicotinic acetylcholine receptor in the brains of patients with Alzheimer's disease and their effect on synaptic proteins in SH-SY5Y cells.

Alzheimer's disease (AD) is a chronic neurodegenerative, and abnormal aggregation of the neurotoxic ß amyloid (Aß) peptide is an early event in AD. The present study aimed to determine the correlation between the nicotinic acetylcholine receptor α7 subunit (α7 nAChR) and Aß in the brains of patients with AD, and to investigate whether the increased expression levels of the α7 nAChR could alter the neurotoxicity of Aß. The expression levels of α7 nAChR and Aß in the brains of patients with AD and healthy brains were analyzed using immunofluorescence. Moreover, SH­SY5Y cells were used to stably overexpress or silence α7 nAChR expression levels, prior to the treatment with or without 1 µmol/l Aß1­42 oligomer (AßO). The mRNA and protein expression levels of α7 nAChR, synaptophysin (SYP), postsynaptic density of 95 kDa (PSD­95) and synaptosomal­associated protein of 25 kDa (SNAP­25) were subsequently analyzed using reverse transcription­quantitative PCR and western blotting. In addition, the concentration of acetylcholine (ACh) and the activity of acetylcholinesterase (AChE) were analyzed using spectrophotometry, while the cell apoptotic rate was determined using flow cytometry. The expression of Aß in the brains of patients with AD was found to be significantly increased, whereas the expression of α7 nAChR was significantly decreased compared with the healthy control group. In vitro, the expression levels of α7 nAChR were significantly increased or decreased following the overexpression or silencing of the gene, respectively. Consistent with these observations, the mRNA and protein expression levels of SYP, PSD­95 and SNAP­25 were also significantly increased following the overexpression of α7 nAChR and decreased following the genetic silencing of the receptor. In untransfected or negative control cells, the expression levels of these factors and the apoptotic rate were significantly reduced following the exposure to AßO, which was found to be attenuated by α7 nAChR overexpression, but potentiated by α7 nAChR RNA silencing. However, no significant differences were observed in either the ACh concentration or AChE activity following transfection. Collectively, these findings suggested that α7 nAChR may protect the brains of patients with AD against Aß, as α7 nAChR overexpression increased the expression levels of SYP, SNAP­25 and PSD­95, and attenuated the inhibitory effect of Aß on the expression of these synaptic proteins and cell apoptosis. Overall, this indicated that α7 nAChR may serve an important neuroprotective role in AD.

Silent Mating-Type Information Regulation 2 Homolog 1 Attenuates the Neurotoxicity Associated with Alzheimer Disease via a Mechanism Which May Involve Regulation of Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-α.

To investigate the neuroprotective role of silent mating-type information regulation 2 homolog 1 (SIRT1) in Alzheimer disease (AD), brain tissues from patients with AD and APP/PS1 mice as well as primary rat neurons exposed to oligomers of amyloid-ß peptide were examined. The animals were treated with resveratrol (RSV) or suramin for 2 months. Cell cultures were treated with RSV, suramin, and the peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α) stimulator ZLN005. Cells were transiently transfected with PGC-1α silencing RNA. The level of SIRT1 in brain tissues from patients with AD and APP/PS1 mice, including nuclear and mitochondrial proteins, as well as in primary neurons exposed to oligomers of amyloid-ß peptide, was decreased. Overexpression of APP/PS1 impaired learning and memory of mice; produced more senile plaques, disrupted membranes, and resulted in broken or absent cristae of mitochondria in the brain; decreased levels of A disintegrin and metallopeptidase domain 10, beta-secretase 2, 8-oxoguanine DNA glycosylase-1, PGC-1α, and NAD+; and increased levels of beta-secretase 1 and apoptosis. Interestingly, these changes were attenuated significantly by RSV treatment but enhanced by suramin administration. By activating PGC-1α but inhibiting SIRT1, apoptotic cell death was significantly decreased; however, by activating SIRT1 but inhibiting PGC-1α with small interfering PGC-1α, these levels remained unchanged. These findings indicate that SIRT1 may protect against AD-associated neurotoxicity, which might involve PGC-1α regulation.

Protections against toxicity in the brains of rat with chronic fluorosis and primary neurons exposed to fluoride by resveratrol involves nicotinic acetylcholine receptors.

Protection of Resveratrol (RSV) against the neurotoxicity induced by high level of fluoride was investigated. Sprague-Dawley (SD) rats and their offspring, as well as cultures of primary neurons were divided randomly into four groups: untreated (control); treated with 50 mg RSV/kg/ (once daily by gavage) or (20 M in the cultured medium); exposed to 50 ppm F- in drinking water or 4 mmol/l in the cultured medium; and exposed to fluoride then RSV as above. The adult rats were treated for 7 months and the offspring sacrificed at 28 days of age; the cultured neurons for 48 h. For general characterization, dental fluorosis was assessed and the fluoride content of the urine measured (by fluoride-electrode) in the rates and the survival of cultured neurons monitored with the CCK-8 test. The spatial learning and memory of rats were assessed with the Morris water maze test. The levels of α7 and α4 nicotinic acetylcholine receptors (nAChRs) were quantified by Western blotting; and the activities of superoxide dismutase (SOD) and catalase (CAT), and the levels of malondialdehyde (MDA) and H2O2 assayed biochemically. The results showed that chronic fluorosis resulted in the impaired learning and memory in rats and their offspring, and more oxidative stress in both rat brains and cultured neurons, which may be associated the lower levels of α7 and α4 nAChR subunits. Interestingly, RSV attenuated all of these toxic effects by fluorosis, indicating that protection against the neurotoxicity of fluoride by RSV might be in mechanism involved enhancing the expressions of these nAChRs.

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.

Activation of α7 nAChR by PNU-282987 improves synaptic and cognitive functions through restoring the expression of synaptic-associated proteins and the CaM-CaMKII-CREB signaling pathway.

Ligands of nicotinic acetylcholine receptors (nAChRs) are widely considered as potential therapeutic agents. The present study used primary hippocampus cells and APPswe/PSEN1dE9 double-transgenic mice models to study the possible therapeutic effect and underlying mechanism of the specific activation of α7 nAChR by PNU-282987 in the pathogenesis of Alzheimer's disease. The results indicated that activation of α7 nAChR attenuated the Aß-induced cell apoptosis, decreased the deposition of Aß, increased the expression of synaptic-associated proteins, and maintained synaptic morphology. Furthermore, in the APP/PS1_DT mice model, activation of α7 nAChR attenuated Aß-induced synaptic loss, reduced the deposition of Aß in the hippocampus, maintained the integral structure of hippocampus-derived synapse, and activated the calmodulin (CaM)-calmodulin-dependent protein kinase II (CaMKII)-cAMP response element-binding protein signaling pathway by upregulation of its key signaling proteins. In addition, activation of α7 nAChR improved the learning and memory abilities of the APP/PS1_DT mice. Collectively, the activation of α7 nAChR by PNU-282987 attenuated the toxic effect of Aß in vivo and in vitro, which including reduced deposition of Aß in the hippocampus, maintained synaptic morphology by partially reversing the expression levels of synaptic-associated proteins, activation of the Ca2+ signaling pathway, and improvement of the cognitive abilities of APP/PS1_DT mice.

Lithium chloride reduced the level of oxidative stress in brains and serums of APP/PS1 double transgenic mice via the regulation of GSK3ß/Nrf2/HO-1 pathway.

Aim: The aim of this study is to investigate whether lithium chloride (LiCl) can regulate glycogen synthase kinase-3ß (GSK3ß)/nuclear factor E2 related factor（Nrf2）/heme oxygenase-1 (HO-1) pathway to reduce the injury of oxidative stress in APP/PS1 double transgenic mice.Materials and Methods: The APP/PS1 double transgenic and wild-type (WT) mice were divided randomly into four groups, i.e. WT, WT + LiCl (LiCl 100 mg/kg by gavage once daily), the transgenic + LiCl and the transgenic groups. The expressions of phosphor-GSK3ß (ser9), Nrf2 and HO-1 at protein levels were detected by Western blotting. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and the content of malondialdehyde (MDA) were measured by related detection kits. Nissl bodies in different brain regions were examined by Nissl staining.Results: The decreased protein levels of phosphor-GSK3ß (ser9), Nrf2 and HO-1, the declined activities of SOD and GSH-Px, the increased content of MDA and the decreased Nissl bodies in neurons were observed in the brains or serums of APP/PS1 mice as compared with WT. The treatment with LiCl attenuated these changes in the levels of GSK3ß/Nrf2/HO-1 pathway and oxidative stress as well as Nissl bodies induced by APP/PS1 mutation.Conclusion: LiCl reversed the declined activities of SOD and GSH-Px and the increased content of MDA as well as the decreased Nissl bodies in neurons in the brains or serums of APP/PS1 mice, the mechanism of which may be involved in the down-regulation of the activity of GSK3ß and consequently enhances the expressions of Nrf2 and HO-1.

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.