Alleviation of behavioral deficits, amyloid-ß deposition, and mitochondrial structure damage associated with mitophagy upregulation in AD animal models via AAV9-IGF-1 treatment.

By safeguarding the neurological system, insulin-like growth factor 1 (IGF-1) may have a role in the etiology of Alzheimer's disease (AD). The mechanism and signaling route, however, remain unclear. This research aimed to investigate the impact of IGF-1 on AD as well as its possible mechanism and signaling route. In this work, intracerebroventricular AAV9-IGF-1 was delivered to APP/PS1 transgenic mice. Following therapy, the Morris water maze and passive avoidance tests were administered to evaluate spatial learning and memory. The elevated plus maze, the open field test, and the sucrose preference test were used to evaluate anxious-depressive-like behavior. Thioflavin S staining was employed to visualize Aß deposition, and ELISA was used to determine the quantities of soluble Aß1-40 and Aß1-42. Transmission electron microscopy was used to view the mitochondrial structure and mitophagy vesicles. The protein expression levels of PINK1, Parkin, and LC3-II/LC3-I were finally determined by Western blotting. AAV9-IGF-1 therapy enhanced spatial learning and memory, relieved anxious-depressive-like behavior impairments, lowered amyloid-ß deposition, and decreased levels of soluble Aß1-40 and Aß1-42. In addition, AAV9-IGF-1 therapy restored mitochondrial integrity and increased the number of mitophagy in transgenic mice expressing APP/PS1. These results indicate that IGF-1 is protective for APP/PS1 mice. The mechanism of the favorable benefits mediated by IGF-1 was connected to an increase in mitophagy, which might give a novel therapy target in the future.

Catalpol Ameliorates Neurotoxicity in N2a/APP695swe Cells and APP/PS1 Transgenic Mice.

Alzheimer's disease (AD) causes progressive decline of memory and cognitive deficits. Because of its complicated pathogenesis, the prevention and therapy of AD remain an enormous challenge. It has been reported that catalpol possessed neuroprotective effects against AD. However, the involved mechanism still needs to be intensively studied. Therefore, the effects of catalpol on N2a/APP695swe cells and APP/PS1 mice were identified in the current study. Catalpol could improve cytotoxicity according to CCK-8 assay and ameliorate cellular morphological changes in N2a/APP695swe cells. Neuronal structural damage in the hippocampal CA1 region of APP/PS1 AD mice was improved according to HE staining and immunohistochemistry of NeuN. Meanwhile, catalpol administration ameliorated cognitive deficits confirmed by behavior performance of APP/PS1 mice. Hoechst 33,342 staining and Annexin V-FITC/PI double staining demonstrated that catalpol could reduce apoptosis in N2a/APP695swe cells. Likewise, TUNEL staining also manifested that catalpol significantly reduced apoptosis in hippocampal CA1 region of APP/PS1 mice. Catalpol administration also could improve mitochondrial functions indicated by the ameliorative mitochondrial morphology, the decreased ROS generation, and the increased MMP in N2a/APP695swe cells. Subsequently, catalpol restrained oligomerization of Aß1-42, verified by a reduced ThT fluorescence dose- and time-dependently. Additionally, both Aß1-40 and Aß1-42 aggregation were decreased in N2a/APP695swe cells and APP/PS1 mice administrated with catalpol confirmed by ELISA and western blot. Western blot also showed that catalpol facilitated the phosphorylation of AKT and GSK3ß, and impeded the expression of BACE1 both in vivo and in vitro. Finally, a slight alteration in lactylation, 2-hydroxyisobutyrylation, and phosphorylation were found in N2a/APP695swe cells treated with catalpol. Together, these findings manifested that catalpol served a neuroprotective effect in AD and might be a novel and expecting prophylactic or curative candidate for AD or neurodegenerative diseases therapy.

Stem Cell Therapy for Alzheimer's Disease.

Alzheimer's disease (AD) is the most common neurodegenerative disease caused by eventually aggregated amyloid ß (Aß) plaques in degenerating neurons of the aging brain. These aggregated protein plaques mainly consist of Aß fibrils and neurofibrillary tangles (NFTs) of phosphorylated tau protein. Even though some cholinesterase inhibitors, NMDA receptor antagonist, and monoclonal antibodies were developed to inhibit neurodegeneration or activate neural regeneration or clear off the Aß deposits, none of the treatment is effective in improving the cognitive and memory dysfunctions of the AD patients. Thus, stem cell therapy represents a powerful tool for the treatment of AD. In addition to discussing the advents in molecular pathogenesis and animal models of this disease and the treatment approaches using small molecules and immunoglobulins against AD, we will focus on the stem cell sources for AD using neural stem cells (NSCs); embryonic stem cells (ESCs); and mesenchymal stem cells (MSCs) from bone marrow, umbilical cord, and umbilical cord blood. In particular, patient-specific-induced pluripotent stem cells (iPS cells) are proposed as a future prospective and the challenges for the treatment of AD.

Zerumbone ameliorates behavioral impairments and neuropathology in transgenic APP/PS1 mice by suppressing MAPK signaling.

BACKGROUND: Alzheimer's disease (AD) is a major clinical problem, but there is a distinct lack of effective therapeutic drugs for this disease. We investigated the potential therapeutic effects of zerumbone, a subtropical ginger sesquiterpene, in transgenic APP/PS1 mice, rodent models of AD which exhibit cerebral amyloidosis and neuroinflammation. METHODS: The N9 microglial cell line and primary microglial cells were cultured to investigate the effects of zerumbone on microglia. APP/PS1 mice were treated with zerumbone, and non-cognitive and cognitive behavioral impairments were assessed and compared between the treatment and control groups. The animals were then sacrificed, and tissues were collected for further analysis. The potential therapeutic mechanism of zerumbone and the signaling pathways involved were also investigated by RT-PCR, western blot, nitric oxide detection, enzyme-linked immunosorbent assay, immunohistochemistry, immunofluorescence, and flow cytometry analysis. RESULTS: Zerumbone suppressed the expression of pro-inflammatory cytokines and induced a switch in microglial phenotype from the classic inflammatory phenotype to the alternative anti-inflammatory phenotype by inhibiting the mitogen-activated protein kinase (MAPK)/nuclear factor-kappa B signaling pathway in vitro. After a treatment period of 20 days, zerumbone significantly ameliorated deficits in both non-cognitive and cognitive behaviors in transgenic APP/PS1 mice. Zerumbone significantly reduced ß-amyloid deposition and attenuated pro-inflammatory microglial activation in the cortex and hippocampus. Interestingly, zerumbone significantly increased the proportion of anti-inflammatory microglia among all activated microglia, potentially contributing to reduced ß-amyloid deposition by enhancing phagocytosis. Meanwhile, zerumbone also reduced the expression of key molecules of the MAPK pathway, such as p38 and extracellular signal-regulated kinase. CONCLUSIONS: Overall, zerumbone effectively ameliorated behavioral impairments, attenuated neuroinflammation, and reduced ß-amyloid deposition in transgenic APP/PS1 mice. Zerumbone exhibited substantial anti-inflammatory activity in microglial cells and induced a phenotypic switch in microglia from the pro-inflammatory phenotype to the anti-inflammatory phenotype by inhibiting the MAPK signaling pathway, which may play an important role in its neuroprotective effects. Our results suggest that zerumbone is a potential therapeutic agent for human neuroinflammatory and neurodegenerative diseases, in particular AD.

Enhanced Anti-Amyloid Effect of Combined Leptin and Pioglitazone in APP/PS1 Transgenic Mice.

BACKGROUND: Alzheimer's disease (AD) has challenged single-target therapeutic strategies, raising the possibility that combined therapies may offer a more effective treatment strategy. OBJECTIVE: There is substantial evidence for the efficacy of leptin (L) (neuroprotective hormone) and pioglitazone (P) (anti-inflammatory agent) as monotherapies in AD. We have previously shown that combination treatment of L+P in APP/PS1 mice at the onset of pathology significantly improved memory and reduced brain Aß levels relative to control mice. In this new study, we sought to replicate our previous findings in a new cohort of APP/PS1 mice to further confirm whether the combined treatment of L+P is superior to each treatment individually. METHODS: We have re-evaluated the effects of L+P co-treatment in APP/PS1 mice using thioflavin-S staining, MOAß immunolabeling, and enzyme-linked immunosorbent assay (ELISA) to examine effects on Aß levels and pathology, relative to animals that received L or P individually. RESULTS: We demonstrated that a combination of L and P significantly enhances the anti-Aß effect of L or P in the hippocampus of APP/PS1 mice. CONCLUSION: Our findings suggest that combining L and P significantly enhances the anti-Aß effect of L or P in the hippocampus of APP/PS1 mice and maybe a potential new effective strategy for AD therapy.

Amelioration of Behavioral Impairments and Neuropathology by Antiepileptic Drug Topiramate in a Transgenic Alzheimer's Disease Model Mice, APP/PS1.

Alzheimer's disease (AD) is a neurodegenerative disease that is the main cause of dementia in the elderly. The aggregation of ß-amyloid peptides is one of the characterizing pathological changes of AD. Topiramate is an antiepileptic drug, which in addition, is used in the treatment of many neuropsychiatric disorders. In this study, the therapeutic effects of topiramate were investigated in a transgenic mouse model of cerebral amyloidosis (APP/PS1 mice). Before, during, and after topiramate treatment, behavioral tests were performed. Following a treatment period of 21 days, topiramate significantly ameliorated deficits in nest-constructing capability as well as in social interaction. Thereafter, brain sections of mice were analyzed, and a significant attenuation of microglial activation as well as ß-amyloid deposition was observed in sections from topiramate-treated APP/PS1 mice. Therefore, topiramate could be considered as a promising drug in the treatment of human AD.

Dl-3-n-Butylphthalide Inhibits NLRP3 Inflammasome and Mitigates Alzheimer's-Like Pathology via Nrf2-TXNIP-TrX Axis.

AIMS: Oxidative stress and neuroinflammation play important roles in the pathology of Alzheimer's disease (AD). Thioredoxin-interacting protein (TXNIP), an endogenous inhibitor of antioxidant thioredoxin, is suspected to be an important modulator of oxidative stress and inflammation. However, the underlying mechanism involved in the abnormal homeostasis of TXNIP-thioredoxin (TrX) in AD pathogenesis remains unclear. RESULTS: Using the Swedish mutant form of APP (APPswe)/PSEN1dE9 transgenic mouse (APP/PS1) and human-derived neuronal cells as model systems, we disclosed the impairment of the nuclear factor erythroid 2-related factor 2 (Nrf2)-TXNIP-TrX signaling in Alzheimer's-like pathology. We observed that the immune staining of TXNIP was increased in postmortem AD brain. The chronic accumulation of inflammatory mediator in neuronal cells facilitates interactions of TXNIP-nucleotide binding oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3) and NLRP3-ASC, which increases ß-amyloid (Aß) secretion. The antioxidant Dl-3-n-butylphthalide (Dl-NBP) is commonly used for cerebral ischemia treatment. In our study, we elucidated for new mechanisms by which Dl-NBP enhanced TrX activity, suppressed TXNIP, and ameliorated neuronal apoptosis in the APP/PS1 mouse brains. In human glioblastoma A172 cells and neuroblastoma SH-SY5Y cells, we delineated the Dl-NBP-mediated signaling pathways by which Dl-NBP-dependent upregulation of Nrf2 mediated the reciprocal regulation of reducing proinflammatory cytokine and inhibiting Aß production in the glial and neuronal cells overexpressing APPswe. INNOVATION: Our data provide a novel insight into the molecular mechanism that impairments of Nrf2-TXNIP-TrX system may be involved in the imbalance of cellular redox homeostasis and inflammatory damage in the AD brain. CONCLUSION: Dl-NBP treatment could suppress TXNIP-NLRP3 interaction and inhibit NLRP3 inflammasome activation via upregulating Nrf2. These findings may provide an instrumental therapeutic approach for AD. Antioxid. Redox Signal. 00, 000-000.

PPARγ agonist-loaded PLGA-PEG nanocarriers as a potential treatment for Alzheimer's disease: in vitro and in vivo studies.

OBJECTIVE: The first aim of this study was to develop a nanocarrier that could transport the peroxisome proliferator-activated receptor agonist, pioglitazone (PGZ) across brain endothelium and examine the mechanism of nanoparticle transcytosis. The second aim was to determine whether these nanocarriers could successfully treat a mouse model of Alzheimer's disease (AD). METHODS: PGZ-loaded nanoparticles (PGZ-NPs) were synthesized by the solvent displacement technique, following a factorial design using poly (lactic-co-glycolic acid) polyethylene glycol (PLGA-PEG). The transport of the carriers was assessed in vitro, using a human brain endothelial cell line, cytotoxicity assays, fluorescence-tagged nanocarriers, fluorescence-activated cell sorting, confocal and transmission electron microscopy. The effectiveness of the treatment was assessed in APP/PS1 mice in a behavioral assay and by measuring the cortical deposition of ß-amyloid. RESULTS: Incorporation of PGZ into the carriers promoted a 50x greater uptake into brain endothelium compared with the free drug and the carriers showed a delayed release profile of PGZ in vitro. In the doses used, the nanocarriers were not toxic for the endothelial cells, nor did they alter the permeability of the blood-brain barrier model. Electron microscopy indicated that the nanocarriers were transported from the apical to the basal surface of the endothelium by vesicular transcytosis. An efficacy test carried out in APP/PS1 transgenic mice showed a reduction of memory deficit in mice chronically treated with PGZ-NPs. Deposition of ß-amyloid in the cerebral cortex, measured by immunohistochemistry and image analysis, was correspondingly reduced. CONCLUSION: PLGA-PEG nanocarriers cross brain endothelium by transcytosis and can be loaded with a pharmaceutical agent to effectively treat a mouse model of AD.

Acute Down-regulation of BDNF Signaling Does Not Replicate Exacerbated Amyloid-ß Levels and Cognitive Impairment Induced by Cholinergic Basal Forebrain Lesion.

Degeneration of basal forebrain cholinergic neurons (BFCNs) precedes hippocampal degeneration and pathological amyloid-beta (Aß) accumulation, and underpins the development of cognitive dysfunction in sporadic Alzheimer's disease (AD). We hypothesized that degeneration of BFCNs causes a decrease in neurotrophin levels in innervated brain areas, which in turn promotes the development of Aß pathology and cognitive impairment. Here we show that lesion of septo-hippocampal BFCNs in a pre-symptomatic transgenic amyloid AD mouse model (APP/PS1 mice) increases soluble Aß levels in the hippocampus, and induces cognitive deficits in a spatial memory task that are not seen in either unlesioned APP/PS1 or non-transgenic littermate control mice. Furthermore, the BFCN lesion results in decreased levels of brain-derived neurotrophic factor (BDNF). However, viral knockdown of neuronal BDNF in the hippocampus of APP/PS1 mice (in the absence of BFCN loss) neither increased the level of Aß nor caused cognitive deficits. These results suggest that the cognitive decline and Aß pathology induced by BFCN loss occur independent of dysfunctional neuronal BDNF signaling, and may therefore be directly underpinned by reduced cholinergic neurotransmission.

Running exercise protects against myelin breakdown in the absence of neurogenesis in the hippocampus of AD mice.

Neurogenesis might influence oligodendrogenesis and selectively instruct myelination in the mammalian brain. Running exercise could induce neurogenesis and protect the myelin sheaths in the dentate gyrus of AD mice. It is unclear whether running exercise can protect myelin sheaths in the absence of neurogenesis in the hippocampus of AD mice. Six-month-old male APP/PS1 transgenic mice were randomly assigned to a control group (Tg control) or a running group (Tg runner), and age-matched non-transgenic littermates were used as a wild-type group (WT control). The Tg runner mice were subjected to a running protocol for four months. The behaviors of the mice in the three groups were then assessed using the Morris water maze, and related quantitative parameters of the myelin sheaths within the CA1 field were investigated using unbiased stereological and electron microscopy techniques. Learning and spatial memory performance, CA1 volume, the volumes of the myelinated fibers, and myelin sheaths in the CA1 field were all significantly worse in the Tg control mice than in the WT control mice. Learning and spatial memory performance, CA1 volume and the volume of the myelin sheaths in the CA1 field were all significantly greater in the Tg runner mice than in the Tg control mice. These results reveal demyelinating lesions in the CA1 field of Alzheimer's disease (AD) mice and indicate that running exercise could protect against myelin sheath degeneration in the absence of neurogenesis, thereby reducing CA1 atrophy and delaying the onset and progression of AD.

Elevation of Divalent Metal Transporter 1 Protein in the Cerebellar Cortex of the APP/PS1 Transgenic Mouse / 中国医科大学学报

Objective To investigate the distribution of divalent metal transporter 1 (DMT1) in the cerebellum of APP/PS1 transgenic mouse. Methods Immunohistochemistry, immunofluorescence, and confocal laser scanning microscopy were used to analyze the relationship between DMTl and amyloid beta (Aβ) and their distribution in senile plaques. Western blotting was used to analyze DMT1 protein level in the APP/PS1 transgenic mouse cerebellum. Results DMTl and Aβ were mainly located in the amyloid plaques, which were predominately located in the molecular layer of the cerebellar cortex of the transgenic mouse. Only a few plaques could be seen in the Purkinje cell layer and granular layer. Confocal laser microscopy revealed the DMTl and Aβ were co-localized in senile plaques. Conclusion The abundant expression of DMTl protein suggests that DMTl and the divalent metal ions that it transports might be involved in the formation of Aβ senile plaques and other pathological processes in the cerebellum in Alzheimer' s disease.

Altered mechanisms of protein synthesis in frontal cortex in Alzheimer disease and a mouse model.

Expression of the nucleolar chaperones nucleolin (NCL) and nucleophosmin (NPM1), upstream binding transcription factor (UBTF), rRNA18S, rRNA28S, and several genes encoding ribosomal proteins (RPs) is decreased in frontal cortex area 8 at advanced stages of Alzheimer's disease (AD). This is accompanied by reduced protein levels of elongation factors eEF1A and eEF2. Changes are more marked in AD cases with rapid course (rpAD), as initiation factor eIF3η is significantly down-regulated and several RP genes up-regulated in rpAD when compared with typical AD. These changes contrast with those seen in APP/PS1 transgenic mice used as a model of AD-like ß-amyloidopathy; Ncl mRNA, rRNA18S, rRNA28S and seven out of fifteen assessed RP genes are up-regulated in APP/PS1 mice aged 20 months; only eEF2 protein levels are reduced in transgenic mice. Our findings show marked altered expression of molecules linked to the protein synthesis machinery from the nucleolus to the ribosome in frontal cortex at terminal stages of AD which differs from that seen in APP/PS1 transgenic mice, thus further suggesting that molecular signals in mouse models do not apply to real human disease counterparts.

Identification of Circulating miR-125b as a Potential Biomarker of Alzheimer's Disease in APP/PS1 Transgenic Mouse.

Alzheimer's disease (AD) is the most common form of dementia, characterized by progressive decline in cognitive abilities of the affected individuals. Biological markers are essential to identify individuals at early stages of the disease for timely therapeutic intervention. Currently, pathological biomarkers are detected either through cerebrospinal fluid analysis or brain imaging, or postmortem, all of which are expensive, invasive, or time consuming. Recently, some studies have shown that circulating miR-125b, miR-181c, miR-9, miR-191-5p, miR-26b-3p, and miR-28-3p may be biomarkers of AD. However, those potential biomarkers are not validated in an AD mouse model. In the current study, we found that circulating miR-125b, miR-9, and miR-191-5p are downregulated, and miR-28-3p is upregulated in an APP/PS1 transgenic mouse model of AD. Furthermore, the correlation analysis shows a positive correlation between the expression of miR-125b and cognitive function of the APP/PS1 transgenic mouse. Moreover, we also determined that the level of serum miR-125b, miR-9, and miR-191-5p were reversed in EGCG-treated APP/PS1 transgenic mouse models. Finally, the expression of miR-125b was significantly downregulated in EGCG-treated SH-SY5Y cells.

Amyloid-ß Derived from the Brain of the Alzheimer's Disease Transgenic Mouse Is Resistant to Proteolytic Digestion Due to Its Conformation.

The main pathological feature of Alzheimer's disease (AD) is the formation of abundant amyloid-ß (Aß) plaques in the human brain. Studies have reported that Aß from the AD brain is resistant to proteolytic digestion, which may explain why Aß cannot be readily eliminated from this organ. However, there are only a few studies that address this important question. We used the AD transgenic mouse (APP/PS1) model to show that Aß derived from the brain of the old mouse is resistant to proteolytic digestion. This was in contrast to the proteinase K-sensitive human Aß peptide, whose amino acid sequence was identical to that of AD mouse-derived Aß but whose conformation was different (i.e., the native protein, but not the peptide, folded into a three-dimensional conformation). To address this question, we denatured AD mouse-derived Aß with urea and found that Aß became proteinase K-sensitive. This phenomenon was concentration-dependent, and these results were confirmed by another protein denaturant, guanidinium hydrochloride. We recovered the conformation of the denatured AD mouse-derived Aß by eliminating urea and adding the human Aß peptide, and we found that human Aß was converted to the proteinase K-resistant form in the presence of partially undenatured AD mouse-derived Aß. However, upon the addition of the rat Aß peptide, there were no Aß proteinase K-resistant fragments. Our results show that the resistance of AD mouse-derived Aß to proteolytic digestion is dependent on the three-dimensional conformation of Aß. In summary, this study provides new insights on why Aß plaques fail to be degraded in the human brain.

Bioinformatics and co-expression network analysis of differentially expressed lncRNAs and mRNAs in hippocampus of APP/PS1 transgenic mice with Alzheimer disease.

APP/PS1 transgenic mice with Alzheimer disease (AD) are widely used as a reliable animal model in studies about behaviors, physiology, biochemistry and histomorphology of AD, but few studies have been conducted to investigate the role of lncRNAs in this model. In this study, lncRNA microarray was employed to detect the gene expression profile and lncRNA expression profile in the mouse brain. Then, bioinformatics was used to predict the differentially expressed genes related to AD (n=20). Among different lncRNAs (n=249), 99 were downregulated and 150 upregulated. Co-expression network was applied to analyze the co-expression of differential lncRNAs and different genes. In network, lncRNA Gm13498 and lncRNA 1700030L20Rik correlated with the most genes and their degrees were 6 and 5, respectively. Then, the function and signal transduction pathways related to the differentially co-expressed lncRNAs were analyzed with bioinformatics, and results showed that these lncRNAs were involved in the systemic development of neurons, intercellular communication, regulation of action potential of neurons, development and differentiation of oligodendrocytes, neurotransmitters transmission, and neuronal regeneration. Realtime PCR was employed to detect the expression of relevant lncRNAs and differentially expressed RNAs in 10 samples, and results were consistent with above findings from microarray.

[Expressions of synaptophysin and BDNF/Trk-B in cerebellum of APPswe/PS1dE9 transgenic mice].

OBJECTIVE: To observe the expressions of synaptophysin and BDNF/Trk-B in cerebellum of APPswe/PS1dE9 transgenic mice. METHODS: The healthy 9-month old APP/PS1 male mice (n1) and the same wild type male mice(n2) were divided into two groups, APP/PS1 group and wild-type(WT) group. The expressions of synaptophysin and brain-derived neurotrophic factor/tyrosine kinase B (BDNF/Trk-B) in cerebellum were determined by Western blot (n1=6; n2=6) and immunohistochemical(n1=4; n2=4).The possible synaptic changes in APP/PS1 group were observed by using electron microscopy. RESULTS: Compared with WT group, the expressions of synaptophsin and BDNF/Trk-B in cerebellum were decreased in APP/PS1 group. Increased width of the synaptic cleft and decreased thickness of postsynaptic density were also observed. CONCLUSIONS: In APP/PS1 group, expressions of synaptophsin and BDNF/Trk-B in cerebellum were decreased; changes in ultrastructure of synapses seemed to be widespread alterations. These findings suggest a possible association between expression of BDNF/TrkB and synaptic plasticity in AD cerebellum.

Enhanced penetration of exogenous EPCs into brains of APP/PS1 transgenic mice.

The aim of this study was to investigate the repair function of exogenous Endothelial progenitor cells (EPCs) for brain microvascular damage of the APP/PS1 transgenic mouse model of Alzheimer's disease (AD). This study used a density-gradient centrifugation method to isolate mononuclear cells (MNCs) from mouse bone marrow, which were subsequently seeded and cultured. Cells were characterized by morphology and detection of the surface markers CD34 and CD133 at different time points by immunofluorescence (IF) and flow cytometry (FCM). Then, EPCs were transfected with GFP adenoviral vectors (GFP-EPCs). Wild-type (WT) and APP/PS1 transgenic mice both received GFP-EPCs injection through the tail vein, and using a PBS buffer injection as the control. Seven days later, the animals' brain tissue was isolated. Expression of GFP was detected by quantitative polymerase chain reaction (qPCR) and western-blot (WB), while the fluorescence of GFP within the brains of mice was observed under a fluorescence microscope. Higher mRNA and protein expression of GFP, accompanied with increased green fluorescence, were detected in the brain of GFP-EPCs-injected APP/PS1 mice, as compared with GFP-EPCs-injected WT mice. The results show that the APP/PS1 transgenic mouse model of AD exhibited enhanced penetration of exogenous EPCs into brains than the WT mice.

BACE1 in the retina: a sensitive biomarker for monitoring early pathological changes in Alzheimer's disease.

Because of a lack of sensitive biomarkers, the diagnosis of Alzheimer's disease (AD) cannot be made prior to symptom manifestation. Therefore, it is crucial to identify novel biomarkers for the presymptomatic diagnosis of AD. While brain lesions are a major feature of AD, retinal pathological changes also occur in patients. In this study, we investigated the temporal changes in ß-site APP-cleaving enzyme 1 (BACE1) expression in the retina and brain to determine whether it could serve as a suitable biomarker for early monitoring of AD. APP/PS-1 transgenic mice, 3, 6 and 8 months of age, were used as an experimental group, and age-matched C57/BL6 wild-type mice served as the control group. In the Morris water maze test, there were no significant differences in escape latency or in the number of crossings in the target area among mice of different ages. Compared with wild-type mice, no changes in learning or memory abilities were detected in transgenic mice at 3 months of age. However, compared with wild-type mice, the escape latency was significantly increased in transgenic mice at 6 months, starting on day 3, and at 8 months, starting on day 2, during Morris water maze training. In addition, the number of crossings of the target area was significantly decreased in transgenic mice. The learning and memory abilities of transgenic mice were further worsened at 8 months of age. Immunohistochemical staining revealed no BACE1 plaques in wild-type mice at 3, 6 or 8 months or in transgenic mice at 3 months, but they were clearly found in the entorhinal cortex, hippocampus and prefrontal cortex of transgenic mice at 6 and 8 months. BACE1 expression was not detected in the retina of wild-type mice at 3 months, but weak BACE1 expression was detected in the ganglion cell layer, inner plexiform layer and outer plexiform layer at 6 and 8 months. In transgenic mice, BACE1 expression in the ganglion cell layer was increased at 3 months, and BACE1 expression in the ganglion cell layer, inner plexiform layer and outer plexiform layer was significantly increased at 6 and 8 months, compared with age-matched wild-type mice. Taken together, these results indicate that changes in BACE1 expression appear earlier in the retina than in the brain and precede behavioral deficits. Our findings suggest that abnormal expression of BACE1 in the retina is an early pathological change in APP/PS-1 transgenic mice, and that BACE1 might have potential as a biomarker for the early diagnosis of AD in humans.

FIBT versus florbetaben and PiB: a preclinical comparison study with amyloid-PET in transgenic mice.

BACKGROUND: Over the last decade, an increasing number of studies have been published on the use of amyloid-ß (Aß) PET imaging with different (18)F-radiopharmaceuticals for clinical characterization of Alzheimer's disease (AD) in different stages. However, distinct study cohorts and different quantification techniques allow only for an indirect comparison between the different tracers. Thus, the aim of this study was the direct intra-individual in vivo comparison of different Aß-targeted radiopharmaceuticals for PET imaging, including the newly developed agent [(18)F]FIBT. METHODS: A small group of four animals of a well-characterized APP/PS1 transgenic (tg) mouse model of AD and gender-matched control (ctl) animals underwent a sequential and standardized PET imaging regimen for direct comparison of [(18)F]FIBT, [(18)F]florbetaben, and [(11)C]PiB. The quantitative PET imaging data were cross-validated with the cerebral Aß plaque load as quantified ex vivo on histological sections. RESULTS: We found that FIBT (2-(p-methylaminophenyl)-7-(2-[(18)F]fluoroethoxy)imidazo[2,1-b]benzothiazole) compares favorably to florbetaben as a high-contrasting PET radiopharmaceutical for imaging Aß pathology. The excellent pharmacokinetics of FIBT in combination with its high-binding affinity towards Aß resulted in feasible high-contrast imaging of Aß with high global cortex to cerebellum standard uptake value ratio (SUVR) in 24-month-old tg mice (tg 1.68 ± 0.15 vs. ctl 0.95 ± 0.02). The SUVRs in transgenic versus control animals (SUVRtg/SUVRctl) for FIBT (1.78 ± 0.16) were similar to the ratios as observed in humans (SUVRAD/SUVRctl) for the established gold standard Pittsburgh compound B (PiB) (1.65 ± 0.41). CONCLUSIONS: This head-to-head PET tracer comparison study in mice indicated the good imaging properties of [(18)F]FIBT, such as high initial brain uptake, fast clearance of the brain, and high binding affinity towards Aß as directly compared to the established amyloid tracers. Moreover, the preclinical study design is recommendable for reliable assessment and comparison of novel radiopharmaceuticals.

Neuroprotective effect of the active components of three Chinese herbs on brain iron load in a mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative brain disorder and the most common cause of dementia. New treatments for AD are required due to its increasing prevalence in aging populations. The present study evaluated the effects of the active components of Epimedium, Astragalus and Radix Puerariae on learning and memory impairment, ß-amyloid (Aß) reduction and brain iron load in an APPswe/PS1ΔE9 transgenic mouse model of AD. Increasing evidence indicates that a disturbance of normal iron homeostasis may contribute to the pathology of AD. However, the underlying mechanisms resulting in abnormal iron load in the AD brain remain unclear. It has been hypothesized that the brain iron load is influenced by the deregulation of certain proteins associated with brain iron metabolism, including divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1). The present study investigated the effects of the active components of Epimedium, Astragalus and Radix Puerariae on the expression levels of DMT1 and FPN1. The treatment with the active components reduced cognitive deficits, inhibited Aß plaque accumulation, reversed Aß burden and reduced the brain iron load in AD model mice. A significant increase was observed in the levels of DMT1-iron-responsive element (IRE) and DMT1-nonIRE in the hippocampus of the AD mouse brain, which was reduced by treatment with the active components. In addition, the levels of FPN1 were significantly reduced in the hippocampus of the AD mouse brain compared with those of control mice, and these levels were increased following treatment with the active components. Thus, the present study indicated that the active components of Epimedium, Astragalus and Radix Puerariae may exert a neuroprotective effect against AD by reducing iron overload in the AD brain and may provide a novel approach for the development of drugs for the treatment of AD.