Brain Of Mouse Model Research Articles

Water Diffusion in the Brain of Chronic Hypoperfusion Model Mice: A Study Considering the Effect of Blood Flow.

Purpose:Chronic cerebral hypoperfusion model mice were created by unilateral common carotid artery occlusion (UCCAO) surgery, which does not cause cerebral infarction, but which does cause long-term reduction in cerebral blood flow (CBF) to the occluded side. Cognitive dysfunction in this mouse model has been demonstrated in behavioral experiments, but neuron density change was not found in a previous positron emission tomography (PET) study. As a next step, in this study we investigated the injury of neuronal fibers in chronic cerebral hypoperfusion model mice using diffusion tensor imaging (DTI).Methods:In diffusion-weighted imaging (DWI), not only the diffusion of water but also the capillary flow in the voxel, i.e., intravoxel incoherent motion (IVIM), contributes to the signal. Thus, we used DTI to evaluate DWI signal changes in the brains of chronic hypoperfusion model mice at 4 weeks after UCCAO while monitoring the possible influence of CBF change using arterial spin-labeling (ASL) MRI.Results:Simple t-tests indicated that there were significant differences in CBF between the control and occluded sides of the brain, but there was no significant difference for the mean diffusivity (MD) or fractional anisotropy (FA). However, as Pearson correlation analysis showed that MD was strongly correlated with CBF, analysis-of-covariance (ANCOVA) was then performed using CBF as a covariate and a significant difference in MD between the contra- and ipsilateral sides was found. Performing a similar procedure for the FA found no significant differences.Conclusion:The results suggest the injury of neuronal fibers due to chronic hypoperfusion. It is also suggested that CBF-related signal changes should be considered when DWI-based information is used for pathological diagnosis.

VEGFR2 alteration in Alzheimer\u2019s disease

Alzheimer’s disease (AD) is a common disorder of progressive cognitive decline among elderly subjects. Angiogenesis-related factors including vascular endothelial growth factor (VEGF) might be involved in the pathogenesis of AD. Soluble form of the VEGF receptor is likely to be an intrinsic negative counterpart of VEGF. We measured the plasma levels of VEGF and its two soluble receptors (sVEGFR1 and sVEGFR2) in 120 control subjects, 75 patients with mild cognitive impairment, and 76 patients with AD using ELISA. Plasma levels of VEGF in patients with AD were higher than those in healthy control subjects. However, plasma levels of sVEGFR1 and sVEGFR2 were lower in patients with AD than in healthy control subjects. Levels of VEGFR2 mRNA were significantly decreased in human umbilical vein endothelial cells after amyloid-beta treatment. Further, protein levels of VEGFR2 were also decreased in the brains of AD model mice. In addition, we show that the expression of sVEGFR2 and VEGFR2 was also decreased by the transfection with the Notch intracellular domain. These results indicate that the alterations of VEGF and its two receptors levels might be associated with those at risk for Alzheimer’s disease.

Neuron-specific methylome analysis reveals epigenetic regulation and tau-related dysfunction of BRCA1 in Alzheimer’s disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease characterized by pathology of accumulated amyloid β (Aβ) and phosphorylated tau proteins in the brain. Postmortem degradation and cellular complexity within the brain have limited approaches to molecularly define the causal relationship between pathological features and neuronal dysfunction in AD. To overcome these limitations, we analyzed the neuron-specific DNA methylome of postmortem brain samples from AD patients, which allowed differentially hypomethylated region of the BRCA1 promoter to be identified. Expression of BRCA1 was significantly up-regulated in AD brains, consistent with its hypomethylation. BRCA1 protein levels were also elevated in response to DNA damage induced by Aβ. BRCA1 became mislocalized to the cytoplasm and highly insoluble in a tau-dependent manner, resulting in DNA fragmentation in both in vitro cellular and in vivo mouse models. BRCA1 dysfunction under Aβ burden is consistent with concomitant deterioration of genomic integrity and synaptic plasticity. The Brca1 promoter region of AD model mice brain was similarly hypomethylated, indicating an epigenetic mechanism underlying BRCA1 regulation in AD. Our results suggest deterioration of DNA integrity as a central contributing factor in AD pathogenesis. Moreover, these data demonstrate the technical feasibility of using neuron-specific DNA methylome analysis to facilitate discovery of etiological candidates in sporadic neurodegenerative diseases.

Integrated approach reveals diet, APOE genotype and sex affect immune response in APP mice

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder that is influenced by genetic and environmental risk factors, such as inheritance of ε4 allele of APOE (APOE4), sex and diet. Here, we examined the effect of high fat diet (HFD) on amyloid pathology and expression profile in brains of AD model mice expressing human APOE isoforms (APP/E3 and APP/E4 mice). APP/E3 and APP/E4 mice were fed HFD or Normal diet for 3months. We found that HFD significantly increased amyloid plaques in male and female APP/E4, but not in APP/E3 mice. To identify differentially expressed genes and gene-networks correlated to diet, APOE isoform and sex, we performed RNA sequencing and applied Weighted Gene Co-expression Network Analysis. We determined that the immune response network with major hubs Tyrobp/DAP12, Csf1r, Tlr2, C1qc and Laptm5 correlated significantly and positively to the phenotype of female APP/E4-HFD mice. Correspondingly, we found that in female APP/E4-HFD mice, microglia coverage around plaques, particularly of larger size, was significantly reduced. This suggests altered containment of the plaque growth and sex-dependent vulnerability in response to diet. The results of our study show concurrent impact of diet, APOE isoform and sex on the brain transcriptome and AD-like phenotype.

Transplantation of rat bone marrow-derived mesenchymal stem cells regulates oxidative stress in Alzheimer’s disease transgenic mouse model

Background: It is widely recognized that increased oxidative damage on neurons is an early event in Alzheimer’s disease (AD). It has been reported that mesenchymal stem cells (MSC) can reduce oxidative stress on many kinds of disease. Our group have shown that the changes in redox status of the AD model mouse brain can be visualized noninvasively using three-dimensional electron paramagnetic resonance (EPR) imaging (Free Radic Biol Med. 2015).

REGULATION OF Aβ- OR ROS-MEDIATED NEURITE DEGENERATION BY AK5

Adenylate kinases (AKs) play a key role in nucleotide metabolism via nucleotide phosphoryl exchange. A new member of this family, Ak5, has recently been identified, but its function remains unknown. In this study, we find that neuronal Ak5 mediates amyloid-beta (Ab) or ROS-mediated neurite degeneration and neurotoxicity. Cell-based functional screening was performed using cell-based tau aggregation assay and cDNA expression library. Primary cortical or hippocampal neurons from mouse embryos (E16 or E18) were prepared and seeded on poly-L-lysine-coated glass cover slips. For Immunocytochemistry, Cells were double-stained with Ak5 and beta-tubulin and washed with PBS before the incubation with FITC-conjugated or TRITC-conjugated secondary antibodies. In vitro microtubule assay was performed using purified AK5 and tubulins. We found that Ak5 is mainly expressed in the hippocampus and cortex of the mouse brains. Compared to AK1, purified Ak5 protein shows little kinase activity in vitro. From pull-down and LC/MS/MS analysis, we found the microtubules as an interaction partner of Ak5 in the mouse brains. Ak5 expression is significantly up-regulated in the neuronal cells exposed to Ab and hydrogen peroxides (H2O2). Also ectopic expression of Ak5 lead to neurite degeneration and neuronal death. Interestingly, Ak5 antagonizes the interaction of tau with microtubules in vitro and in cells. Furthermore, expression of Ak5 is increased in the brains of AD model mice and patients. We conclude that Ak5 plays a novel role in Ab- or ROS-mediated neurite degeneration via its competitive binding with tau to microtubules, providing insight into a mechanism for tau-mediated neurodegeneration in AD. Reference: Park H, Kam TI, Kim Y, Choi H, Gwon Y, Kim C, Koh JY, Jung YK (2012) Neuropathogenic role of adenylate kinase-1 in Aβ-mediated tau phosphorylation via AMPK and GSK3β. Hum Mol Genet 21: 2725–2737. Solaroli N, Panayiotou C, Johansson M, Karlsson A (2009) Identification of two active functional domains of human adenylate kinase 5. FEBS Lett 583: 2872–2876.

β-ALANYL-3-METHYL-L-HISTIDINE, ANSERINE, AMELIORATES COGNITIVE DEFICITS IN AGED APPSWE/PSEN1DE9 ALZHEIMER’S DISEASE MODEL MOUSE THROUGH THE IMPROVEMENT OF BLOOD VESSEL DYSFUNCTION AS WELL AS GLIAL NEUROINFLAMMATORY REACTIONS

We have recently discovered that a formula containing imidazole dipeptides improve cognitive functions of healthy elderly people. In this study, we tested whether anserine would improve the cognitive declines in aged AD model mice. In addition, to elucidate the effect of anserine on the AD model mouse, we investigated the blood vessel dysfunction as well as the glial neuroinflammatory reactions occurred in aged AD model mice. B6C3-Tg (APPswe/PSEN1dE9) 85Dbo/J AD model transgenic mouse was used in this study. We prepared the two groups of aged AD model mice for the anserine and placebo treated group. To assess the effect of anserine for the memory function, we performed the Morris Water Maze (MWM) test. The levels of Aβ accumulations in the hippocampus were evaluated by histochemical staining and ELISA. In AD model mice, inflammation often appears inducing the glial neuroinflammatory reactions and the dysfunction of the blood vessel system. To evaluate the extent of the glial inflammatory reactions, we performed immunostaining for astrocytes and microglia. The amount of inflammatory cytokine IL-1β was compared between the two groups by ELISA. To evaluate the blood vessels dysfunction, we used tomato lectin and anti-PDGFR-β to visualize the vascular endothelial cells and the capillary pericytes, respectively. In the probe test of the MWM, the memory decline was recovered by the treatment of anserine. Anserine had no effect on the formation of the senile plaques and the accumulation of Aβ1–42. Whereas, the decrease of the expression of astrocyte and inflammatory cytokine IL-1β was detected in the anserine treated group. An increasing coverage rate of pericyte was observed in the anserine treatment group. This data indicated that the anserine treatment protected blood vessel system of AD model mouse brain and then suppressed the neuroinflammation in the brain of AD model mouse. The administration of anserine in the aged AD model mice showed the improvement of the cognitive declines. The anserine treatment showed the improvement toward blood vessel dysfunction as well as glial neuroinflammatory reactions. Through these favorable functions, it is possible that the treatment of anserine may contribute to the improvement of the cognitive functions of AD patients.

Poly(trehalose) Nanoparticles Prevent Amyloid Aggregation and Suppress Polyglutamine Aggregation in a Huntington's Disease Model Mouse.

Prevention and therapeutic strategies for various neurodegenerative diseases focus on inhibiting protein fibrillation, clearing aggregated protein plaques from the brain, and lowering protein-aggregate-induced toxicity. We have designed poly(trehalose) nanoparticles that can inhibit amyloid/polyglutamine aggregation under extra-/intracellular conditions, reduce such aggregation-derived cytotoxicity, and prevent polyglutamine aggregation in a Huntington's disease (HD) model mouse brain. The nanoparticles have a hydrodynamic size of 20-30 nm and are composed of a 6 nm iron oxide core and a zwitterionic polymer shell containing ∼5-12 wt % covalently linked trehalose. The designed poly(trehalose) nanoparticles are 1000-10000 times more efficient than molecular trehalose in inhibiting protein fibrillation in extra-cellular space, in blocking aggregation of polyglutamine-containing mutant huntingtin protein in model neuronal cells, and in suppressing mutant huntingtin aggregates in HD mouse brain. We show that the nanoparticle form of trehalose with zwitterionic surface charge and a trehalose multivalency (i.e., number of trehalose molecules per nanoparticle) of ∼80-200 are crucial for efficient brain targeting, entry into neuronal cells, and suppression of mutant huntingtin aggregation. The present work shows that nanoscale trehalose can offer highly efficient antiamyloidogenic performance at micromolar concentration, compared with millimollar to molar concentrations for molecular trehalose. This approach can be extended to in vivo application to combat protein-aggregation-derived neurodegenerative diseases.

Ebselen ameliorates β-amyloid pathology, tau pathology, and cognitive impairment in triple-transgenic Alzheimer's disease mice.

Alzheimer's disease (AD) is a progressive neurodegenerative disease which is clinically characterized by memory loss and cognitive decline caused by protein misfolding and aggregation. Imbalance between free radicals and the antioxidant system is a prominent and early feature in the neuropathology of AD. Selenium (Se), a vital trace element with excellent antioxidant potential, is preferentially retained in the brain in Se-limited conditions and has been reported to provide neuroprotection through resisting oxidative damage. In this paper, we studied for the first time the potential of Ebselen, a lipid-soluble selenium compound with GPx-like activity, in the treatment of cognitive dysfunction and neuropathology of triple-transgenic AD (3×Tg-AD) mice, AD model cell, and primary culture. We demonstrated that Ebselen inhibited oxidative stress in both AD model cells and mouse brains with increasing GPx and SOD activities and meanwhile reduced p38 mitogen-activated protein kinases activities. By decreasing the expression of amyloid precursor protein and β-secretase, Ebselen reduced the levels of Aβ in AD neurons and mouse brains, especially the most toxic oligomeric form. Besides, mislocation of phosphorylated tau in neurons and phosphorylation levels of tau protein at Thr231, Ser396, and Ser404 residues were also inhibited by Ebselen, probably by its regulatory roles in glycogen synthase kinase 3β and protein phosphatase 2A activity. In addition, Ebselen mitigated the decrease of synaptic proteins including synaptophysin and postsynaptic density protein 95 in AD model cells and neurons. Consequently, the spatial learning and memory of 3×Tg-AD mice were significantly improved upon Ebselen treatment. This study provides a potential novel therapeutic approach for the prevention of AD.

Semi-automatic synthesis and biodistribution of N-(2-18F-fluoropropionyl)-bis(zinc (II)-dipicolylamine) (18F-FP-DPAZn2) for AD model imaging

BackgroundPhosphatidylserine (PS)-targeting positron emission tomography (PET) imaging with labeled small-molecule tracer is a crucial non-invasive molecule imaging method of apoptosis. In this study, semi-automatic radiosynthesis and biodistribution of N-(2-18F-fluoropropionyl)-bis(zinc(II)-dipicolylamine) (18F-FP-DPAZn2), as a potential small-molecule tracer for PET imaging of cell death in Alzheimer’s disease (AD) model, were performed.Methods18F-FP-DPAZn2 was synthesized on the modified PET-MF-2V-IT-I synthesizer. Biodistribution was determined in normal mice and PET images of AD model were obtained on a micro PET-CT scanner.ResultsWith the modified synthesizer, the total decay-corrected radiochemical yield of 18F-FP-DPAZn2 was 35 ± 6% (n = 5) from 18F− within 105 ± 10 min. Biodistribution results showed that kidney has the highest uptake of 18F-FP-DPAZn2. The uptake of radioactivity in brain kept at a relatively low level during the whole observed time. In vivo 18F-FP-DPAZn2 PET images demonstrated more accumulation of radioactivity in the brain of AD model mice than that in the brain of normal mice.ConclusionsThe semi-automatic synthetic method provides a slightly higher radiochemical yield and shorter whole synthesis time of 18F-FP-DPAZn2 than the manual operation method. This improved method can give enough radioactivity and high radiochemical purity of 18F-FP-DPAZn2 for in vivo PET imaging. The results show that 18F-FP-DPAZn2 seems to be a potential cell death tracer for AD imaging.

Dual-functional nanoparticles for precise drug delivery to Alzheimer’s disease lesions: Targeting mechanisms, pharmacodynamics and safety

Alzheimer’s disease (AD) is the most common form of dementia and is characterized by the cerebral accumulation of extracellular amyloid plaques. In a previous study, this histopathological hallmark was used as a target on a dual-functional nanoparticle (TQNP) to deliver biotechnological drugs, such as the H102 peptide, a β-sheet breaker, to AD lesions precisely. This delivery system could reduce the amyloid-β (Aβ) burden in the brains of AD model mice, as well as ameliorated the memory impairment of the mice. Regretfully, the mechanism how nanoparticles penetrated the BBB and subsequently targeted to the plaques is still unclear. In this study, the internalization, subcellular fate and transportation of the nanoparticles on bEnd.3 cells and an in vitro BBB model, demonstrated that TQNP could be taken up through various routes, including caveolae-mediated endocytosis, suggesting that some of TQNP were able to cross the BBB intact. Then, the TQNP were visualized to specifically bind to the Aβ plaques. TQNP targeting to amyloid plaques might lead to enhanced therapeutic efficacy, which was further evaluated in APP/PS1 transgenic mice. The TQNP/H102 obtained better ability in decreasing amyloid plaques, increasing Aβ-degrading enzymes, reducing tau protein phosphorylation, protecting synapses and improving the spatial learning and memory of transgenic mice than nanoparticles modified with a single ligand. And good biocompatibility of TQNP was indicated with subacute toxicity assays. In conclusion, TQNP was a valuable nanodevice for the precise delivery for biotechnological drugs to treat AD.

Increased acetylation of Peroxiredoxin1 by HDAC6 inhibition leads to recovery of A\u03b2-induced impaired axonal transport

BackgroundReduction or inhibition of histone deacetylase 6 (HDAC6) has been shown to rescue memory in mouse models of Alzheimer’s disease (AD) and is recently being considered a possible therapeutic strategy. However, the restoring mechanism of HDAC6 inhibition has not been fully understood.Methods and resultsHere, we found that an anti-oxidant protein Peroxdiredoxin1 (Prx1), a substrate of HDAC6, malfunctions in Aβ treated cells, the brains of 5xFAD AD model mice and AD patients. Malfunctioning Prx1, caused by reduced Prx1 acetylation levels, was recovered by HDAC6 inhibition. Increasing acetylation levels of Prx1 by HDAC6 inhibition recovered elevated reactive oxygen species (ROS) levels, elevated Ca2+ levels and impaired mitochondrial axonal transport, sequentially, even in the presence of Aβ. Prx1 mutant studies on the K197 site for an acetylation mimic or silencing mutation support the results showing that HDAC6 inhibitor restores Aβ-induced disruption of ROS, Ca2+ and axonal transport.ConclusionsTaken together, increasing acetylation of Prx1 by HDAC6 inhibition has several beneficial effects in AD pathology. Here, we present the novel mechanism by which elevated acetylation of Prx1 rescues mitochondrial axonal transport impaired by Aβ. Therefore, our results suggest that modulation of Prx1 acetylation by HDAC6 inhibition has great therapeutic potential for AD and has further therapeutic possibilities for other neurodegenerative diseases as well.

Krüppel-like factor 4 regulates amyloid-β (Aβ)-induced neuroinflammation in Alzheimer’s disease

Alzheimer’s disease (AD), one of the most common neurodegenerative diseases, is characterized by extracellular deposition of amyloid-β (Aβ) peptide, and neuro-inflammatory processes mediated by microglial activation are known to play a pivotal role in AD. However, the expression pattern and function of Krüppel-like factor (KLF) 4 in AD remain unknown. In this study, KLF4 was found to be increased at both the gene and protein levels in response to incubation with oligomeric Aβ42 in a dose-dependent manner in BV2 microglial cells. An in vivo study also displayed that expression of KLF4 in the brains of J20 transgenic AD model mice was increased due to accumulation of Aβ. Mechanistically, activation of p53 resulting from an increase in phosphorylation at ser15 was verified as the mediator of the oligomeric Aβ42-induced expression of KLF4. Subsequent experiments have demonstrated that KLF4 silencing in BV2 cells attenuates oligomeric Aβ42-induced neuroinflammation by ameliorating the release of proinflammatory cytokines, such as tumor necrosis factor-a (TNF-α), interleukin (IL)-1β, IL-6, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). In addition, overexpression of KLF4 promoted oligomeric Aβ42-induced neuroinflammation by exacerbating the release of pro-inflammatory factors. These results suggest a KLF4 plays a potential role in oligomeric Aβ42-induced neurotoxicity and the pathogenesis of AD.

Cyclodextrin has conflicting actions on autophagy flux in vivo in brains of normal and Alzheimer model mice.

2-hydroxypropyl-β-cyclodextrin (CYCLO), a modifier of cholesterol efflux from cellular membrane and endo-lysosomal compartments, reduces lysosomal lipid accumulations and has therapeutic effects in animal models of Niemann-Pick disease type C and several other neurodegenerative states. Here, we investigated CYCLO effects on autophagy in wild-type mice and TgCRND8 mice-an Alzheimer's Disease (AD) model exhibiting β-amyloidosis, neuronal autophagy deficits leading to protein and lipid accumulation within greatly enlarged autolysosomes. A 14-day intracerebroventricular administration of CYCLO to 8-month-old TgCRND8 mice that exhibit moderately advanced neuropathology markedly diminished the sizes of enlarged autolysosomes and lowered their content of GM2 ganglioside and Aβ-immunoreactivity without detectably altering amyloid precursor protein processing or extracellular Aβ/β-amyloid burden. We identified two major actions of CYCLO on autophagy underlying amelioration of lysosomal pathology. First, CYCLO stimulated lysosomal proteolytic activity by increasing cathepsin D activity, levels of cathepsins B and D and two proteins known to interact with cathepsin D, NPC1 and ABCA1. Second, CYCLO impeded autophagosome-lysosome fusion as evidenced by the accumulation of LC3, SQSTM1/p62, and ubiquitinated substrates in an expanded population of autophagosomes in the absence of greater autophagy induction. By slowing substrate delivery to lysosomes, autophagosome maturational delay, as further confirmed by our in vitro studies, may relieve lysosomal stress due to accumulated substrates. These findings provide in vivo evidence for lysosomal enhancing properties of CYCLO, but caution that prolonged interference with cellular membrane fusion/autophagosome maturation could have unfavorable consequences, which might require careful optimization of dosage and dosing schedules.

New Implications for the Role for Ubiquilin-1 in Molecular Mechanisms of Alzheime's Disease: Interrelationship with BACE1

Ample evidence links ubiquilins to the pathogenesis of various neurodegenerative disorders. Ubiquilin-1 (also called PLIC-1) is associated to the pathogenesis of Alzheimer’s disease (AD) both genetically and functionally as indicated by investigations in different in vitro and in vivo models and human brain. Previous studies by us and others have identified ubiquilin-1 as a central regulator of the metabolism, subcellular localization, trafficking, as well as accumulation and degradation of various neurodegenerative disease-linked proteins, including the AD-associated β-amyloid precursor protein (APP) and presenilins. Our recent report reveals a previously uncharacterized relationship between ubiquilin-1 and AD-associated β-site cleaving enzyme 1 (BACE1), the rate-limiting enzyme in the generation of the β-amyloid (Aβ) peptides, in cell-based model systems in vitro as well as in the brains of AD model mice in vivo and human patients. Our data suggest that ubiquilin-1 controls BACE1 levels and localization to the late endosomal compartment, the preferred cellular site for Aβ generation. Therefore, the observed decreased levels of ubiquilin-1 in AD brain may result in altered APP processing and Aβ accumulation. Here, we provide a short review on the links between ubiquilin-1 and mechanisms of AD and some other neurodegenerative diseases and then summarize the data in our recent report regarding the newly observed interrelationship between ubiquilin-1 and BACE1.

Human adipose-derived stem cells ameliorate repetitive behavior, social deficit and anxiety in a VPA-induced autism mouse model

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder characterized by impairments in social interaction and communication, and patients often display co-occurring repetitive behaviors. Although the global prevalence of ASD has increased over time, the etiology and treatments for ASD are poorly understood. Recently, some researchers have suggested that stem cells have therapeutic potential for ASD. Thus, in the present study, we investigated the therapeutic effects of human adipose-derived stem cells (hASCs), a kind of autologous mesenchymal stem cells (MSCs) isolated from adipose tissue, on valproic acid (VPA)-induced autism model mice. Human ASCs were injected into the neonatal pups (P2 or P3) intraventricularly and then we evaluated major behavior symptoms of ASD. VPA-treated mice showed increased repetitive behaviors, decreased social interactions and increased anxiety but these autistic behaviors were ameliorated through transplantation of hASCs. In addition, hASCs transplantation restored the alteration of phosphatase and tensin homolog (PTEN) expression and p-AKT/AKT ratio in the brains of VPA-induced ASD model mice. The decreased level of vascular endothelial growth factor (VEGF) and interleukin 10 (IL-10) by VPA were rescued in the brains of the hASC-injected VPA mice. With these results, we experimentally found hASCs’ therapeutic effects on autistic phenotypes in a ASD model mice for the first time. This animal model system can be used to elucidate further mechanisms of therapeutic effects of hASCs in ASD.

Reduced molecular size and altered disaccharide composition of cerebral chondroitin sulfate upon Alzheimer's pathogenesis in mice.

Alzheimer's disease (AD) is a progressive disorder leading to cognitive impairment and neuronal loss. Cerebral extracellular accumulation and deposition of amyloid ß plaques is a pathological hallmark of AD. Chondroitin sulfate (CS) is an extracellular component abundant in the brain. CS is a sulfated glycosaminoglycan covalently attached to a core protein, forming chondroitin sulfate proteoglycan. The structure of CS is heterogeneous with sulfation modification and elongation of the chain. The structural diversity of CS allows it to play various roles in the brain. Increasing evidence has shown that CS promotes aggregation of amyloid ß peptides into higher-order species such as insoluble amyloid ß fibrils. Difficulties in the structural analysis of brain CS, as well as its heterogeneity, limit the study of potential roles of CS in AD pathology. Here we established a microanalysis method with reversed-phase ion-pair high performance liquid chromatography and found that CS in the brains of Tg2576 AD model mice show a lower molecular size and an increased ratio of CS-B motif di-sulfated disaccharide. Our findings provide insight into the structural changes of cerebral CS upon Alzheimer's pathogenesis.

PPARγ agonist pioglitazone improves cerebellar dysfunction at pre-Aβ deposition stage in APPswe/PS1dE9 Alzheimer's disease model mice

Alzheimer's disease (AD) is one of the best known neurodegenerative diseases; it causes dementia and its pathological features include accumulation of amyloid β (Aβ) and neurofibrillary tangles (NFTs) in the brain. Elevated Cdk5 activity and CRMP2 phosphorylation have been reported in the brains of AD model mice at the early stage of the disease, but the significance thereof in human AD remains unelucidated. We have recently reported that Aβ accumulation in the cerebellum of AD model APPswe/PS1dE9 (APP/PS1) mice, and cerebellar dysfunctions, such as impairment of motor coordination ability and long-term depression (LTD) induction, at the pre-Aβ accumulation stage.In the present study, we found increased phosphorylation levels of CRMP2 as well as increased p35 protein levels in the cerebellum of APP/PS1 mice. Interestingly, we show that pioglitazone, an agonist of peroxisome proliferator-activated receptor γ, normalized the p35 protein and CRMP2 phosphorylation levels in the cerebellum. Impaired motor coordination ability and LTD in APP/PS1 mice were ameliorated by pioglitazone treatment at the pre-Aβ accumulation stage. These results suggest a correlation between CRMP2 phosphorylation and AD pathophysiology, and indicate the effectiveness of pioglitazone treatment at the pre-Aβ accumulation stage in AD model mice.

MGlu5 positive allosteric modulation normalizes synaptic plasticity defects and motor phenotypes in a mouse model of Rett syndrome.

Rett syndrome (RS) is a neurodevelopmental disorder that shares many symptomatic and pathological commonalities with idiopathic autism. Alterations in protein synthesis-dependent synaptic plasticity (PSDSP) are a hallmark of a number of syndromic forms of autism; in the present work, we explore the consequences of disruption and rescue of PSDSP in a mouse model of RS. We report that expression of a key regulator of synaptic protein synthesis, the metabotropic glutamate receptor 5 (mGlu5) protein, is significantly reduced in both the brains of RS model mice and in the motor cortex of human RS autopsy samples. Furthermore, we demonstrate that reduced mGlu5 expression correlates with attenuated DHPG-induced long-term depression in the hippocampus of RS model mice, and that administration of a novel mGlu5 positive allosteric modulator (PAM), termed VU0462807, can rescue synaptic plasticity defects. Additionally, treatment of Mecp2-deficient mice with VU0462807 improves motor performance (open-field behavior and gait dynamics), corrects repetitive clasping behavior, as well as normalizes cued fear-conditioning defects. Importantly, due to the rationale drug discovery approach used in its development, our novel mGlu5 PAM improves RS phenotypes and synaptic plasticity defects without evoking the overt adverse effects commonly associated with potentiation of mGlu5 signaling (i.e. seizures), or affecting cardiorespiratory defects in RS model mice. These findings provide strong support for the continued development of mGlu5 PAMs as potential therapeutic agents for use in RS, and, more broadly, for utility in idiopathic autism.

Region-specific changes in the distribution of transient receptor potential vanilloid 4 channel (TRPV4) in the central nervous system of Alzheimer’s disease model mice

Transient receptor potential vanilloid type 4 (TRPV4) channel is expressed in the central nervous system and its role in development of Alzheimer’s disease (AD) is largely unknown. To identify AD-related changes in the TRPV4 channel distribution in the central nervous system, we investigated the distribution and level changes of TRPV4 in brains of AD model mice. The expressions of TRPV4 in the brain of control mice, early stage and late stage AD model mice were compared using immunohistochemistry with antibodies recognizing TRPV4 on free floating sections and in addition we performed western blotting to supplement our findings. TRPV4 immunoreactivity was significantly increased in the cerebral cortex, hippocampal formation, striatum and thalamus of AD model mice compared with control mice. In the cerebral cortex, TRPV4 immunoreactivity was significantly increased in pyramidal cells of early stage and late stage AD model mice. In addition, TRPV4 immunoreactivity was increased in the hippocampal formation, striatum and thalamus of late stage AD model mice. This is the first demonstration of AD-related increases in TRPV4 expression in the brain and it may provide useful data for investigating the pathogenesis of AD-related neurodegenerative diseases. The regulation of TRPV4 in AD mouse model and its functional significance require further investigation.