Tau Protein Expression Research Articles

Prolonged Antibiotic Use Worsens Neuroinflammation and Increases the Risk of Neurodegeneration via Elevated Expression of Systemic IL‐6 in Gulf War Illness Symptom Persistence Murine Model

Prolonged use of fluoroquinolone class of antibiotics has been studied widely. This class of antibiotic has been reported to have side effects linked to cardiovascular, gastrointestinal and neuronal ramifications following long-term usage. Though the Veterans Affairs has reported a recent drop in antibiotic prescriptions, it is still used in higher number of veterans and use of fluoroquinolones is no exception. Gulf War Illness (GWI) pathology is widely believed to be the result of environmental co-exposures and use of the pyridostigmine bromide pills. Advancing our recent studies on GWI pathology in a mouse model we hypothesized that prolonged use (5 months) of fluoroquinolones coupled with Neomycin might augment poor outcomes in systemic inflammation and neuroinflammation. In this study using a symptom persistence mouse model of GWI, we studied the combinatorial effect of prolonged broad spectrum antibiotic Neomycin and Enrofloxacin treatment for 5 months. Expression of serum proinflammatory cytokine IL-6 saw a sharp increase in mice co-exposed with antibiotics and GW chemicals group (GW-Ab) over GW chemical treated group only (GW). Results also showed decreased expression of blood brain barrier (BBB) tight junction protein Claudin 5 in GW-Ab group when compared to GW group. There was an increased microglial activation, expression of cytokine IL-1β, IL-6 and 3-nitrotyrosine and decreased expression of brain derived neurotrophic factor (BDNF) was also observed in GW-Ab group when compared to GW group. To study whether observed disruption of BBB membrane integrity, increased neuroinflammation had any effect on neurodegeneration and neuroplasticity, we probed the mouse brain for Tau and BDNF receptor expression. Results showed that there was an increased expression of phospho Tau (neurodegenerative marker) and decreased expression of phospho-tropomycin receptor kinase B (TrkB)-receptor of BDNF in GW-Ab group when compared to GW group. Interestingly, elevated expression of glycoprotein 130, a receptor for IL-6 trans signaling was also observed in GW-Ab over GW group. This led us to infer that circulatory IL-6 might be an active mediator in worsening brain pathology observed in GW-Ab, especially since IL-6 has been reported to cross BBB through disruption of tight junction proteins. Mechanistically, studies in mouse astrocytes primed with IL-6 also showed a decreased expression of TrkB with increased expression of Tau protein and further confirmed our in vivo results. Thus we conclude that prolonged antibiotic usage exacerbated GWI-associated neuroinflammation and neurodegeneration in GWI symptom persistence.

Application of neurotrophic factor-secreting cells (astrocyte - Like cells) in the in-vitro Alzheimer’s disease-like pathology on the human neuroblastoma cells

This study investigated physical proximity and paracrine activity of neurotrophic factor-secreting cells (NTF-SCs) on beta-amyloid treated cells. Mesenchymal stem cells (MSCs) - to-NTF-SCs (Astrocyte –like cells) trans-differentiation was confirmed using immunofluorescence staining of GFAP. BDNF and NGF levels were measured by ELISA. To mimic AD-like condition, SH-SY5Y cells were exposed to 10 μM Aβ1–42. SH-SY5Y cells were allocated into Control; and Aβ1–42-treated cells. Treated cells were further classified into three subgroups including Aβ1–42 cells, Aβ1–42 cells + NTF-SCs (CM) and Aβ1–42 cells + NTF-SCs co-culture. Cell viability was measured by MTT assay. Anti-inflammatory and anti-tau hyperphosphorylation effects of NTF-SCs were assessed via monitoring TNF-α and hyperphosphorylated Tau protein expression level respectively. To explore the impact of NTF-SCs on synaptogenesis and synaptic functionality, real-time PCR assay was performed to measure the expression of synapsine 1, homer 1 and ZIF268. The level of synaptophysin was monitored via immunofluorescence staining. Data showed MSCs potential in trans-differentiating toward NTF-SCs indicated with enhanced GFAP expression (p < 0.05). ELISA assay confirmed the superiority of NTF-SCs in releasing NGF and BDNF compared to the MSCs (p < 0.05). Aβ significantly induced SH-SY5Y cells death while juxtacrine and paracrine activity of NTF-SCs significantly blunted these conditions (p < 0.05). Trans-differentiated cells had potential to reduce Tau hyperphosphorylation and TNF-α level after treatment with Aβ through juxtacrine and paracrine mechanisms (p < 0.05). Moreover, NTF-SCs significantly increased the expression rate of synapsin 1, homer 1 and zif 268 genes in Aβ-treated cells compared to matched-control group coincided with induction of synaptophysin at the protein level(p < 0.05). NTF-SCs reversed AD-like neuropathological alterations in SH-SY5Y cells via paracrine and juxtacrine mechanisms.

Simultaneous Detection of Six Isoforms of Tau Protein in Human Cerebrospinal Fluid by Multidimensional Mass Spectrometry-Based Targeted Proteomics

Abnormal expression of Tau protein can cause the development of Alzheimer's disease (AD). So far, much evidence has demonstrated that Tau has multiple isoforms. These isoforms are suggested to have distinct physiological roles and contribute unequally to the progress of AD. Thus, detection of individual Tau isoforms may be helpful to better understand the link between clinical outcome and Tau status and to further improve AD diagnosis and treatment. However, few studies have been conducted on absolute quantification of Tau isoforms, probably due to high sequence homology and also low abundance of these isoforms in biofluids such as cerebrospinal fluid (CSF). Therefore, mass spectrometry-based targeted proteomics was attempted here. This targeted proteomics approach can principally measure a protein of interest at the surrogate peptide level, yet little has been done to detect protein isoforms, probably due to lack of isoform-specific surrogate peptides in mass spectrometry. In this study, separations in more dimensions were added, including immunoprecipitation (IP) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for sample pretreatment and systems of linear equations for post-lab data extraction. Moreover, the reliability of the approach including IP enrichment, gel separation, and linear algebra algorithms was discussed. As a result, each isoform of Tau protein can be individually detected and quantified. Using IP enrichment, ∼250-fold enhancement of sensitivity was achieved. The ultimate LOQ was 0.50 nM. Finally, this multidimensional mass spectrometry-based targeted proteomics assay was validated and applied to simultaneous quantitative analysis of six Tau isoforms in CSF of AD patients.

Alginate-Derived Mannuronate Oligosaccharide Attenuates Tauopathy through Enhancing Autophagy.

Polymannuronate (PM) is an acidic polysaccharide prepared from alginate, contained in edible brown seaweeds. An unsaturated mannuronate oligosaccharide (MOS) is an enzymatically depolymerized oligosaccharide prepared from PM. The effects of MOS on attenuating tauopathy were studied in HEK293/Tau cells and primary triple transgenic (3×Tg) neurons. MOS inhibited heparin-induced aggregation of the Tau-K18 oligomer and suppressed the levels of phosphorylated Tau protein. MOS treatment reduced the activity of glycogen synthase kinase-3β (GSK-3β) by decreasing its phosphorylation levels on the sites of Y216 and increasing phosphorylation levels on the sites of S9. MOS treatment increased the ratio of LC3-II/LC3-I levels and reduced the expression of p62, indicating an increase in autophagy. Finally, MOS-induced decrease in Tau protein expression was attenuated by the addition of an autophagy inhibitor, confirming the involvement of autophagy. These data support MOS as a promising functional food or potential pharmaceutics for attenuating Tau protein-related disease.

MicroRNA-146a regulates the expression of the Aβ1-42 protein in Alzheimer's disease.

To investigate the expression and clinical significance of microRNA-146a, Aβ1-42, and tau protein in the peripheral blood of patients with Alzheimer's disease (AD). A total of 98 AD patients admitted to our hospital were selected as the experimental group and 50 healthy individuals were selected as the control group. The correlations between microRNA-146a, Aβ1-42, and tau protein were analyzed using receiver operating curves to evaluate the value of microRNA-146a in predicting AD. Bioinformatics analysis was performed to preliminarily explore the possible mechanisms of microRNA-146a in the pathogenesis of AD. MicroRNA-146a, Aβ1-42 and tau protein were differentially expressed between AD patients and healthy individuals (p<0.05). microRNA-146a was negatively correlated with Aβ1-42 (r=-0.882, p<0.05) but was not correlated with tau protein (p>0.05). The ROC curve showed that the area under the curve for microRNA-146a could be used to predict AD with an accuracy of 0.879 (95% CI 0.812-0.947). Bioinformatics analysis showed that the differentially expressed genes (DEGs) of microRNA-146a may be involved in the pathogenesis of AD through the regulation of multiple signaling pathways, including the Toll-like receptor signaling pathway, the neurotransmitter regulatory signaling pathways, and other pathways that affect the inflammatory response, synapse formation, and other biological processes. MicroRNA-146a, Aβ1-42 and tau protein are differentially expressed in the peripheral blood of AD patients. These proteins may be involved in the pathogenesis of AD by regulating the activity of multiple signaling pathways and the expression of the Aβ1-42 protein.

Prevention of β-amyloid-induced toxicity in a differentiated neuronal (IMR32) cell line by Khaya grandifololia (Welw) C. DC.

Alzheimer’s disease (AD) belongs to the class of neurodegenerative disorder and is biochemically characterized by amyloid-β (Aβ) plaques deposition, accumulation of neurofibrillary tangles (NFTs) accumulation and ultimately neuronal loss. Even though, the progress made in developing efficient AD therapy, there is no effective drug capable to stop and/or slow down AD progression. In the current article, we investigated the neuroprotective effect of Khaya grandifololia crude extract and fraction 2 against Aβ 42 -induced cytotoxicity and hyperphosphorylation of tau protein in differentiated neuronal cells (IMR32). Reactive oxygen species production, apoptosis and mitochondrial dynamics and function, synaptic protein, and tau phosphorylation were evaluated using fluorescence microscopy and immunoblotting. Cell viability was assessed using the MTT assay. Findings revealed that exposure of differentiated IMR32 cells to Aβ 42 alone induced the impairment of mitochondrial dynamics, decrease synaptic protein expression and increase hyperphosphorylation of tau protein (phospho tau181). In contrast, the presence of crude extract and KGf2 significantly inhibited the cleavage of Caspase-3 activation. In addition, the levels of synaptic proteins (Symptosomal associated protein 25 and Synaptosin) and superoxide dismutase were restored upon treatment with crude extract and fraction 2. Hyperphosphorylation of tau protein (Thr181) and ERK (Thr202/Tyr205) activities were also significantly reduced after treatment with crude extract and fraction 2. Our findings suggest that KG extract is a potential source for candidate drug against AD and may contribute to the development of efficient therapeutic strategy against AD.

Artemether Attenuates Aβ25-35-Induced Cognitive Impairments by Downregulating Aβ, BACE1, mTOR and Tau Proteins.

Alzheimer's disease (AD) is clinically characterized as a progressive cognitive impairment and behavioral disorder. Pathological hallmarks of AD include extracellular senile plaques (SPs), intracellular neurofibrillary tangles (NFTs) and massive neuronal loss. Although the exact cause of AD is not well understood, a mounting body of evidence has demonstrated that the pathogenesis of AD is associated with oxidative stress, neu-roinflammation, and amyloid beta (Aβ) induced neural apoptosis. Moreover, overexpression of β-secretase 1 (BACE1), Aβ, mammalian target of rapamycin (mTOR), and Tau proteins are closely related to cognitive symptoms in AD. Studies have demonstrated that artemether, an antimalarial drug with acceptable side effects, possesses protective effects against neuroinflammation and oxidative stress. Importantly, artemether can easily penetrate the blood brain barrier, thereby representing an ideal drug candidate for AD treatment. The effect of artemether on memory protection and the associated molecular mechanisms were investigated in an Aβ25-35 induced cognitive impairments rat model. Results of the in vivo study showed that oral administration of artemether significantly attenuated Aβ25-35-induced cognitive impairment in rats. Results of the in vitro study revealed that artemether significantly downregulated the endogenous expression of Aβ, BACE1, mTOR, and Tau proteins in N2a cells. The beneficial effect of artemether against Aβ 25-35-induced cognitive impairments was attributable to the downregulation of the expression of Aβ, BACE1, mTOR, and Tau proteins, suggesting the potential of artemether as an effective, neuronal protective, and multi-targeted drug candidate for AD treatment.

Factors of Cell Degeneration or Death caused by Mutant Tau Protein

Tau protein is a microtubule associated protein mainly expressed in neurons. Under pathological conditions, Tau protein is abnormally hyperphosphorylated and separated from microtubules. Abnormal Tau aggregates form nerve fiber tangles, which are insoluble aggregates in the brain. It is due to the microtubule rupture caused by Tau protein dysfunction and it is associated with neurofibrillar degeneration in Alzheimer's disease.This paper studies several reports and research on the structure and function of Tau protein, the role of Tau protein in pathological diseases and its relationship with neurodegenerative diseases. This paper concludes that Tau protein has undergone abnormal modification and aggregation in many neurodegenerative diseases, but the specific type of Tau protein that causes neurotoxicity, as well as the pathogenesis of its phosphorylation and functional injury inducing nerve apoptosis, are still not fully understood. Various abnormal modifications of Tau protein occur under pathological conditions, and fatal cascade events occur at different stages of neuron apoptosis. Therefore, the causes and effects of cytotoxicity mediated by Tau protein are very complicated. Different or even opposite conclusions are sometimes drawn in Tau protein-mediated neurodegeneration studies. This may be due to differences in Tau protein type, gene mutation and protein expression level.

Prophylactic effects of sporoderm-removed Ganoderma lucidum spores in a rat model of streptozotocin-induced sporadic Alzheimer's disease

Ethnopharmacological relevanceGanoderma lucidum (G. lucidum, Lingzhi), also known as “immortality mushroom” has been broadly used to improve health and longevity for thousands of years in Asia. G. lucidum and its spores have been used to promote health, based on its broad pharmacological and therapeutic activity. This species is recorded in Chinese traditional formula as a nootropic and has been suggested to improve cognitive dysfunction in Alzheimer's disease. However, little is known about the nootropic effects and molecular mechanism of action of G. lucidum spores. Aim of the studyThe present study investigated the protective effects of sporoderm-deficient Ganoderma lucidum spores (RGLS) against learning and memory impairments and its mechanism of action. Materials and methodsIn the Morris water maze, the effects of RGLS on learning and memory impairments were evaluated in a rat model of sporadic Alzheimer's disease that was induced by an intracerebroventricular injection of streptozotocin (STZ). Changes in amyloid β (Aβ) expression, Tau expression and phosphorylation, brain-derived neurotrophic factor (BDNF), and the BDNF receptor tropomyosin-related kinase B (TrkB) in the hippocampus were evaluated by Western blot. ResultsTreatment with RGLS (360 and 720 mg/kg) significantly enhanced memory in the rat model of STZ-induced sporadic Alzheimer's disease and reversed the STZ-induced increases in Aβ expression and Tau protein expression and phosphorylation at Ser199, Ser202, and Ser396. The STZ-induced decreases in neurotrophic factors, including BDNF, TrkB and TrkB phosphorylation at Tyr816, were reversed by treatment with RGLS. ConclusionThese findings indicate that RGLS prevented learning and memory impairments in the present rat model of STZ-induced sporadic Alzheimer's disease, and these effects depended on a decrease in Aβ expression and Tau hyperphosphorylation and the modulation of BDNF-TrkB signaling in the hippocampus.

Identifying early markers of synaptic dysfunction in a mouse model of tauopathy

AbstractBackgroundSynaptic degeneration is currently the best correlate of cognitive decline in Alzheimer’s Disease. Tau pathology, one of the hallmarks of the disease, correlates well with synaptic degeneration and has been shown to abnormally mislocate to synapses in the disease. This process is thought to induce changes in the activity, number and structure of synapses leading to widespread synaptic dysfunction prior to neurodegeneration. However, the precise mechanistic and functional changes are unclear. Therefore, identifying early markers of synaptic dysfunction will provide novel insights into mechanistic changes that precede neurodegeneration and underlie symptomatic onset in tauopathy.MethodTo investigate this, we used a multi‐faceted approach to characterise synaptic changes in the somatosensory cortex of the rTg4510 model of tauopathy, just prior (5.5 months) and post (7.5 months) neurodegeneration. Synaptic, neuronal and network function was assessed using in vitro and in vivo whole‐cell patch clamp electrophysiology, which allows for post‐hoc complementary analysis of morphology in recorded neurons. Protein expression of glutamatergic receptors, synaptic markers and tau were also quantified in crude synaptosomes by western blot.ResultPrior to neurodegeneration, glutamatergic synaptic function was altered (decreased NMDA:AMPA ratio) and dendritic structure was altered (increased branching proximal to soma). Protein expression of synaptic markers and AMPA receptors were significantly decreased in the somatosensory cortex. Post neurodegeneration, a reduction in AMPA mediated synaptic communication was observed (sEPSC frequency), matched with a progressive decrease in AMPA receptor expression and the synaptic marker, PSD95.ConclusionOur results suggest that glutamatergic signalling is altered differently at the regional and single cell level just prior to neurodegeneration. For example, whilst regional AMPA receptor expression decreases pre‐neurodegeneration in the brain, it appears to be partially compensated for functionally within single neurons and the larger network. We predict that there may be a degree of compensation within the network, which when past a threshold leads to widescale network alterations and symptomatic changes. Deconstructing how functional compensation occurs in the brain in neurodegenerative diseases will shed light on how to delay symptomatic onset in tauopathies.

Expression of mutant human tau protein drives synaptic loss in Caenorhabditis elegans

AbstractBackgroundTau aggregation is associated with many neurodegenerative diseases, and inter‐neuronal neurofibrillary lesions composed of tau are a defining characteristic of various tauopathies, including Alzheimer’s disease. Additionally, mutations in human tau have been linked to several neurodegenerative disorders with varying phenotypic effects. How tau aggregation results in altered neuronal function is complex and not yet fully understood. Animal models are powerful tools to probe tau aggregation‐dependent phenotypes. However, they can take a long time to mature and give phenotypes, are created in different genetic backgrounds and can require death of the animal to visualize outcomes. Thus, new models that can avoid some of these issues can facilitate a better understanding of tauopathies.MethodWe have generated multiple lines of transgenic C. elegans expressing different variants of the longest isoform of human tau (htau40) in neurons to better understand how aggregation might cause subsequent downstream events leading to increased toxicity. We have used synaptic markers to examine the consequences of tau aggregation on synaptic integrity during aging.ResultWhen broadly expressed throughout the nervous system an aggregation prone htau40 variant (3PO) or an FTDP‐17 associated mutation (P301L) resulted in decreased lifespan, as well as a decreased locomotor capability as animals aged. Decreased lifespan, along with cognitive and motor defects, are associated with human tauopathies, suggesting our model is reproducing consequences relevant to human disorders. When we selectively express mutated htau40 in the GABAergic motorneurons, we find an age‐associated decline in the number of GABAergic motor neuron synapses, importantly, in the absence of other indicators of neuronal degeneration, i.e. axons and cell bodies were still intact. We have also begun testing mutations in C. elegans orthologs of known Alzheimer’s risk factors and found that loss of the LAR‐like receptor tyrosine phosphatase enhances the synaptic loss due to mutations in htau40.ConclusionC. elegans models of tauopathies permit an analysis of synaptic phenotypes in living animals. Our model can be used to probe both tau variants and other genetic modifiers to better understand how tau aggregation impacts neuronal homeostasis and function.

Tau hyperphosphorylation in the retinal ganglion cells is attenuated upon silencing of SHP2 phosphatase

AbstractBackgroundHuman and animal studies demonstrate that both amyloid precursor protein and phosphorylated Tau which are hallmark proteins associated with Alzheimer’s disease (AD) pathology are perturbed in the retinal tissues. The accumulation of pTau in the retina in addition to the brain tissue suggests eye as a valuable structure for disease diagnosis and to study the disease mechanisms in neurodegenerative disease. Recent studies in human tissues and animal models have established a molecular overlap of AD with glaucoma in the eyes and both the diseases demonstrate altered amyloid beta and Tau phosphorylation profile. We show that Shp2 interacts with Tau protein in retina and silencing this phosphatase in the retinal ganglion cells using AAV2 mediated gene therapy can protect the retina.MethodAnimal model of ocular hypertension was generated by repeat administration of polystyrene beads into the anterior chamber of rat eyes for 8 weeks resulting in sustained elevation of intraocular pressure (20.84±1.65 mmHg). Tau expression changes were investigated both in the animal model and human tissues obtained from the Sydney Eye bank (n=3) using immunohistochemical and WB. Silencing of Shp2 expression in the inner retina was achieved using intravitreal administration of AAV2 constructs under the control of CAG hybrid promoter. The animals were monitored for 2 months after Shp2 silencing and effects on Tau protein expression studied (n=48).ResultIncreased Tau Ser404 phosphorylation was observed in both human glaucoma retinas (p&lt;0.02; student t‐test) and in the animal model of glaucoma (p&lt;0.05) in the WB and immunohistochemical analysis. Shp2 silencing (82±4%) was achieved using AAV2 administration and transduction was monitored using GFP staining. A 7.5±3‐fold downregulation Shp2 expression was achieved using shRNAmir that resulted in significant reduction of pTau Ser404 levels in the inner retina (p&lt;0.028, Bornferroni post‐hoc test) indicating a regulatory effect of the phosphatase on the pTau levels.ConclusionThis study demonstrates that TauSer404 phosphorylation in the retina in vivo is regulated by Shp2 phosphatase. Targeted gene therapy approaches to modulate Shp2 expression can be used as a novel strategy to reduce Tau pathology in the neural tissues in various neurodegenerative disorders.

Alzheimer's disease improved through the activity of mitochondrial chain complexes and their gene expression in rats by boswellic acid.

The foremost neurodegenerative disease is Alzheimer's (AD), which is characterized as a gradual decrease in memory, cognitive function, and also personal changes occurred. This study aims to assess the role of boswellic bioactive component in control Alzheimer's disease through enhancing mitochondrial electron transport chain complexes in the rat model. Rats were divided into five equal groups: the control group (G1), boswellic acid control group (G2), AD disease group (G3), boswellic acid -pre-treated group (G4) and boswellic acid-treated group (G5). At the end of the experiment, blood glucose level, tau protein, different neurochemicals parameters (dopamine, acetylcholine), L-malondialdehyde (MDA) levels, and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities was determined. Also, GLUT2 and mitochondrial electron transport chain complexes were evaluated. As a result, an increase in hippocampus glucose, tau protein expression, MDA and GLUT2 in the AD group (G3) compared to control groups (G1 and G2) has been recorded. These parameters were declined after pre (G4) and treated (G5) by boswellic acid. The neurochemicals, antioxidants parameters, four mitochondrial chain complexes activities and their gene expression in the hippocampus of the AD group were decreased compared to the control groups (G1 and G2). In contrast, pre and treated groups by boswellic acid (G4 and G5, respectively) have shown an increase in antioxidants parameters, and the activities of four mitochondrial complexes, with the best improvement in the pre-treated group (G4), then treated group (G5). In conclusion; the boswellic acid improved the antioxidant and mitochondrial complexes in Alzheimer's disease.

Electroacupuncture Improves Cognitive Function in Senescence-Accelerated P8 (SAMP8) Mice via the NLRP3/Caspase-1 Pathway.

Background. Clinically, electroacupuncture (EA) is the most common therapy for aging-related cognitive impairment (CI). However, the underlying pathomechanism remains unidentified. The aims of this study were to observe the effect of EA on cognitive function and explore the potential mechanism by which EA acts on the NLRP3/caspase-1 signaling pathway. Main Methods. Thirty male SAMP8 mice were randomly divided into the model, the 2 Hz EA and 10 Hz EA groups. Ten male SAMR1 mice were assigned to the control group. Cognitive function was assessed through the Morris water maze test. Hippocampal morphology and cell death were observed by HE and TUNEL staining, respectively. The serum IL-1β, IL-6, IL-18, and TNF-α levels were measured by ELISA. Hippocampal NLRP3, ASC, caspase-1, GSDM-D, IL-1β, IL-18, Aβ, and tau proteins were detected by Western blotting. Key Findings. Cognitive function, hippocampal morphology, and TUNEL-positive cell counts were improved by both EA frequencies. The serum IL-1β, IL-6, IL-18, and TNF-α levels were decreased by EA treatment. However, 10 Hz EA reduced the number of TUNEL-positive cells in the CA1 region and serum IL-1β and IL-6 levels more effectively than 2 Hz EA. NLRP3/caspase-1 pathway-related proteins were significantly downregulated by EA, but 2 Hz EA did not effectively reduce ASC protein expression. Interestingly, both EA frequencies failed to reduce the expression of Aβ and tau proteins. Significance. The effects of 10 Hz EA at the GV20 and ST36 acupoints on the NLRP3/caspase-1 signaling pathway may be a mechanism by which this treatment relieves aging-related CI in mice.

Functional Interactions of Tau Phosphorylation Sites That Mediate Toxicity and Deficient Learning in Drosophila melanogaster.

Hyperphosphorylated Tau protein is the main component of the neurofibrillary tangles, characterizing degenerating neurons in Alzheimer’s disease and other Tauopathies. Expression of human Tau protein in Drosophila CNS results in increased toxicity, premature mortality and learning and memory deficits. Herein we use novel transgenic lines to investigate the contribution of specific phosphorylation sites previously implicated in Tau toxicity. These three different sites, Ser238, Thr245, and Ser262 were tested either by blocking their phosphorylation, by Ser/Thr to Ala substitution, or pseudophosphorylation, by changing Ser/Thr to Glu. We validate the hypothesis that phosphorylation at Ser262 is necessary for Tau-dependent learning deficits and a “facilitatory gatekeeper” to Ser238 occupation, which is linked to Tau toxicity. Importantly we reveal that phosphorylation at Thr245 acts as a “suppressive gatekeeper”, preventing phosphorylation of many sites including Ser262 and consequently of Ser238. Therefore, we elucidate novel interactions among phosphosites central to Tau mediated neuronal dysfunction and toxicity, likely driven by phosphorylation-dependent conformational plasticity.

Lister hooded rats as a novel animal model of attention-deficit/hyperactivity disorder

Appropriate animal models are necessary to determine the molecular and cellular mechanisms underlying attention-deficit/hyperactivity disorder (ADHD). This study used a battery of behavioral tests to compare Lister hooded rats (LHRs), an old outbred strain frequently used for autistic epilepsy research, with Wistar rats and spontaneously hypertensive rats (SHRs), a commonly used ADHD model. The open field, elevated plus maze, light/dark box, and drop tests demonstrated that LHRs were the most hyperactive animals and displayed the most inattentive- and impulsive-like behaviors, which are characteristics of ADHD. The radial arm maze, social interaction, and Morris water maze tests showed that LHRs did not display deficits characteristic of autism or intellectual disability. Although LHRs did not show different monoamine contents, the mRNA expression levels of various genes linked to ADHD (Cdh13, Drd5, Foxp2, Maoa, Sema6d, Slc9a9, and St3gal3) and tyrosine hydroxylase protein expression levels were lower in the prefrontal cortex of LHRs compared with that of Wistar rats or SHRs. c-Fos, synapsin I, and tau protein expression levels in the prelimbic region of the medial prefrontal cortex were also increased in LHRs compared with Wistar rats. Atomoxetine and guanfacine, commonly used non-stimulant treatments for ADHD, ameliorated ADHD-like behaviors in LHRs. These results suggest that LHRs can serve as a better ADHD model to develop novel pharmacological interventions.

Ellagic Acid Inhibits Neuroinflammation and Cognitive Impairment Induced by Lipopolysaccharides.

Neuroinflammation is a predisposing factor for the development of cognitive impairment and dementia. Among the new molecules that are currently being studied, ellagic acid (EA) has stood out for its neuroprotective properties. The present study investigated the effects of ellagic acid in the object recognition test, oxidative stress, cholinergic neurotransmission, glial cell expression, and phosphorylated Tau protein expression. For this, 32 male Wistar rats received an intraperitoneal (IP) application of lipopolysaccharides (LPS) at a dose of 250µg/kg or 0.9% saline solution (SAL) for 8 days. Two hours after the IP injections, the animals received 100mg/kg of EA or SAL via intragastric gavage. Behavioral parameters (open field test and object recognition) were performed on days 5, 6, and 7 of the experimental periods. The results showed that the treatment with EA in the LPS group was able to inhibit cognitive impairment, modulate the immune system response by significantly reducing glial cell expression, attenuating phosphorylated Tau and oxidative damage with consequent improvement in the antioxidant system, as well as preventing the increase of acetylcholinesterase activity. Thus, the neuroprotective effects of EA and its therapeutic potential in cognitive disorders secondary to neuroinflammation were demonstrated.

Effect of electroacupuncture on cyclin-dependent kinase 5 and Tau protein in hippocampus of SAMP8 mice

To observe the effect of electroacupuncture (EA) and manual acupuncture (MA) on learning-memory ability, changes of ultrastructure of neurons and expression of CDK5 and Tau proteins in hippocampus of SAMP8 mice，so as to explore its mechanisms underlying improvement of Alzheimer's disease (AD)．. A total of 45 male SAMP8 mice were randomly divided into model, EA and MA groups, with 15 mice in each group. The other 15 SAMR1 mice were used as the normal group. In the EA group, EA (2 Hz, 1 mA) was applied to bilateral "Shenshu"(BL23) and manual acupuncture was applied to "Baihui"(GV20) for 20 min. In the MA group, MA was applied to GV20 and bilateral BL23 for 20 min. Both group were treated once a day for 31 days, and with an interval of one day between every two 7 days. Morris water maze was performed to assess the animals' learning-memory ability. The morphological changes of hippocampal neurons were observed under transmission electron microscopy. The expression levels of CDK5, p25 and Tau-5 proteins in the hippocampus were detected by immunohistochemistry and Western blot, separately. ①Compared with the normal group, the average escape latency of Morris water maze test was prolonged in the model group(P<0.05, P<0.01), duration of swimming in the original platform quadrant and the number of original platform crossing were significantly shorter and less respectively (P<0.01). Compared with the model group, the average escape latency in the EA group was shortened (P<0.05, P <0.01), the duration of swimming in the original platform quadrant and the number of original platform crossing were significantly prolonged and increased (P<0.01); The average escape latency in the MA group was shortened (P<0.05, P <0.01)，and the duration of swimming in the original platform quadrant was prolonged (P<0.05). Compared with the EA group, the average escape latency of the MA group was prolonged (P<0.05), the duration of swimming in the original platform quadrant was shortened(P<0.05). ②Transmission electron microscopy revealed that the neurons in the hippocampal CA1 area had irregular shape and vague structure, reduction in size and number of mitochondria accompanied with swelling, and malformed changes of mitochondrial crest in the model group, which was relatively milder in both EA and MA groups. ③The expression levels of hippocampal Tau-5, p25 and CDK5 proteins were significantly up-regulated in the model group in contrast to the normal group (P<0.01, P<0.05), and obviously down-regulated in both EA and MA groups relevant to the model group (P<0.05, P<0.01). Compared with the EA group, the expression levels of p25 and CDK5 proteins were significantly increased in the MA group (P<0.05). EA of BL23 can improve the learning-memory ability in SAMP8 mice, which is associated with its effect in down-regulating the expression of hippocampal CDK5, p25 and Tau-5 proteins.

Dilated Perivascular Space in the Midbrain May Reflect Dopamine Neuronal Degeneration in Parkinson’s Disease

Background: The imbalance between the production and clearance of alpha-synuclein and its consequent accumulation plays a pivotal role in the pathogenesis of Parkinson’s disease (PD). The diminished clearance of alpha-synuclein may be partly attributable to impaired interstitial fluid, which can be reflected by the extent of dilated perivascular space (dPVS). We studied the association between dPVS and dopamine neuronal degeneration.Method: We screened 71 healthy controls (HCs) and 88 patients from the Parkinson Progression Markers Initiative (PPMI) database. The dPVS was evaluated in different brain regions on axial T2-weighted images, and dopamine transporter (DAT) imaging data was used to elucidate the extent of dopaminergic neuronal degeneration. Patients with PD were further divided into two groups (SN + PD and SN − PD groups) according to whether dPVS was observed in the substantia nigra (SN). DAT uptake values and clinical scales were compared between the patients with PD and HCs and against dPVS scores. We also investigated the correlation between baseline dPVS scores and longitudinal DAT changes.Results: Relative to the HCs, patients with PD had more dPVS in the SN and basal ganglia (BG). PD patients with dPVS in the SN region exhibited greater expression of tau protein in cerebrospinal fluid (P = 0.038) and a trend towards decreased DAT binding (P = 0.086) relative to those without SN dPVS. No correlations were found between dPVS scores and DAT uptake values or between dPVS scores and longitudinal DAT changes.Conclusion: The dPVS in the SN of patients with PD may reflect the degeneration of dopaminergic neurons.

Coenzyme Q10 alleviates sevoflurane‑induced neuroinflammation by regulating the levels of apolipoprotein E and phosphorylated tau protein in mouse hippocampal neurons.

Sevoflurane may exert neurotoxic effects on the developing brain. Coenzyme Q10 (CoQ10) has been reported to reduce sevoflurane anesthesia-induced cognitive deficiency in 6-day-old mice. However, its specific mechanisms remain unknown. Apolipoprotein E (ApoE) has been reported to lead to the initiation of neurodegeneration in patients with Alzheimer's disease (AD) and may serve an important role in anesthesia-induced neurotoxicity. The present study aimed to reveal the role of ApoE in the pathogenesis of tau protein hyperphosphorylation and neuroinflammation enhancement caused by sevoflurane anesthesia, as well as the protective mechanism of CoQ10 in an anesthetic sevoflurane treatment model of primary mouse hippocampal neurons. For that purpose, the neurons were randomly assigned to the following groups: i) Control; ii) sevoflurane; iii) control+corn oil; iv) sevoflurane+corn oil; v) control+CoQ10; and vi) control+CoQ10. CoQ10 or corn oil alone was added to the medium on day 4 of neuron culture. The neurons in the sevoflurane group were treated with 21% O2, 5% CO2 and 4.1% sevoflurane for 4 h, whereas the control group only with 21% O2 and 5% CO2 on day 5. Samples were collected immediately after anesthesia or control treatment. ATP, superoxidase dismutase (SOD)1, ApoE mRNA, total ApoE, full-length ApoE, ApoE fragments, Tau5, Tau-PS202/PT205 (AT8), Tau-PSer396/404 (PHF1), tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β levels were measured with ELISA, quantitative PCR, western blotting and immunocytochemistry. The results of the present study indicated that sevoflurane anesthesia significantly decreased the ATP and SOD levels, but increased ApoE mRNA, total ApoE protein, full-length ApoE, ApoE fragments, phosphorylated tau (AT8 and PHF1) and neuroinflammatory factor (TNF-α, IL-6 and IL-1β) expression levels compared with those in the control group. The use of CoQ10 reversed the expression of these factors. These results suggested that sevoflurane treatment damaged mouse hippocampal neurons, which may be associated with the expression of ApoE and its toxic fragments. CoQ10 improved energy replenishment and inhibited oxidative stress, which may lead to a decrease in ApoE and phosphorylated tau protein expression, thus mitigating the sevoflurane-induced neuroinflammation in mouse hippocampal neurons.