Effects of a Dehydroevodiamine-Derivative on Synaptic Destabilization and Memory Impairment in the 5xFAD, Alzheimer's Disease Mouse Model

Behavioral and pathological characteristics of 5xFAD female mice in the early stage

Alzheimer's disease (AD) is a central nervous system degenerative disease with insidious onset and gradual development caused by selective and progressive loss of neurons. The 5xFAD mouse is a relatively mature disease model of AD. However, the behavioral research on 5xFAD female mouse is more focused on the changes of late memory function, and the exploration of its early behavioral and pathological changes is still incomplete. This research aims to explore the changes in memory function, emotional function (including anxiety and depression), motor ability, amyloid plaques, glial cell response and neurogenesis in the hippocampus of female 5xFAD mice in the early stage, laying a foundation for a comprehensive exploration of the disease mechanism of AD. The results of this study found that early 4-month-old female 5xFAD mice mainly showed a decline in memory function without other dysfunction. Accompanied by a large amount of amyloid protein plaques deposited in the hippocampus, it induced the response of microglia and astrocytes, and neurogenesis decreased significantly with age, especially in early female 5xFAD mice, which resulted in a decrease in the number of new neurons. This may be an important reason for the decline in memory function of female 5xFAD mice in the early stage.

Hearing modulation affects Alzheimer's disease progression linked to brain inflammation: a study in mouse models

BACKGROUND

Recent studies have identified hearing loss (HL) as a primary risk factor for Alzheimer's disease (AD) onset. However, the mechanisms linking HL to AD are not fully understood. This study explored the effects of drug-induced hearing loss (DIHL) on the expression of proteins associated with AD progression in mouse models.

METHODS

DIHL was induced in 5xFAD and Tg2576 mice aged 3 to 3.5 weeks using kanamycin (700 mg/kg, subcutaneous) and furosemide (600 mg/kg, intraperitoneal). The accumulation and expression of beta-amyloid (Aβ), ionized calcium-binding adaptor molecule 1 (Iba1), and glial fibrillary acidic protein (GFAP) were measured through immunohistochemistry and immunoblotting. Additionally, the expression of proteins involved in the mammalian target of rapamycin (mTOR) pathway, including downstream effectors p70 ribosomal S6 kinase (p70S6K) and S6, as well as proinflammatory cytokines, was analyzed.

RESULTS

Compared to control conditions, HL led to a significant increase in the accumulation of Aβ in the hippocampus and cortex. Elevated levels of neuroinflammatory markers, including Iba1 and GFAP, as well as proinflammatory cytokines such as interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-alpha (TNF-α), were observed. Moreover, DIHL enhanced phosphorylation of mTOR, p70S6K, and S6, indicating activation of the mTOR pathway.

CONCLUSIONS

HL significantly increases Aβ accumulation in the brain. Furthermore, HL activates astrocytes and microglia, leading to increased neuroinflammation and thereby accelerating AD progression. These findings strongly suggest that HL contributes autonomously to neuroinflammation, highlighting the potential for early intervention in HL to reduce AD risk.

Dehydroevodiamine Alleviates Doxorubicin-Induced Cardiomyocyte Injury by Regulating Neuregulin-1/ErbB Signaling

Background: Doxorubicin (DOX) is a widely used antitumor drug; however, its use is limited by the risk of serious cardiotoxicity. Dehydroevodiamine (DHE) is a quinazoline alkaloid which has antiarrhythmic effects. The aim of this study was to investigate the protective effect of DHE on doxorubicin-induced cardiotoxicity (DIC) and its potential mechanism. Materials and Methods: Rat H9c2 cardiomyocytes were exposed to DOX for 24 h to establish a DOX-induced cardiomyocyte injury model. DHE and ErbB inhibitor AG1478 were used to treat H9c2 cells to investigate their effects. Cell counting kit-8 (CCK-8) and lactate dehydrogenase (LDH) release assays were used to evaluate cell viability. Flow cytometry and caspase-3 activity assay were used to detect apoptosis. Western blot was used to detect the expression levels of apoptosis-related proteins and neuregulin-1 (NRG1)/ErbB pathway-related proteins. The levels of proinflammatory cytokines and markers of oxidative stress were also detected, respectively. Quantitative polymerase chain reaction (qPCR) was used to detect mRNA expression levels of hub genes. Results: DHE enhanced cardiomyocyte viability and decreased LDH release in a concentration- and time-dependent manner. DHE also significantly inhibited DOX-induced cardiomyocyte apoptosis, inflammation, and oxidative stress. Bioinformatics analysis showed that the protective mechanism of DHE against DIC was related to ErbB signaling pathway. DOX treatment significantly reduced NRG1, p-ErbB2, and p-ErbB4 protein expression levels in cardiomyocytes, while DHE pretreatment reversed this effect. ErbB inhibitor AG1478 reversed the protective effect of DHE on cardiomyocytes. Conclusion: DHE protects cardiomyocytes against DOX by regulating NRG1/ErbB pathway. DHE may be a potential agent for the prevention and treatment of DIC.

Rbm8a regulates neurogenesis and reduces Alzheimer's disease-associated pathology in the dentate gyrus of 5×FAD mice

Alzheimer's disease is a prevalent and debilitating neurodegenerative condition that profoundly affects a patient's daily functioning with progressive cognitive decline, which can be partly attributed to impaired hippocampal neurogenesis. Neurogenesis in the hippocampal dentate gyrus is likely to persist throughout life but declines with aging, especially in Alzheimer's disease. Recent evidence indicated that RNA-binding protein 8A (Rbm8a) promotes the proliferation of neural progenitor cells, with lower expression levels observed in Alzheimer's disease patients compared with healthy people. This study investigated the hypothesis that Rbm8a overexpression may enhance neurogenesis by promoting the proliferation of neural progenitor cells to improve memory impairment in Alzheimer's disease. Therefore, Rbm8a overexpression was induced in the dentate gyrus of 5×FAD mice to validate this hypothesis. Elevated Rbm8a levels in the dentate gyrus triggered neurogenesis and abated pathological phenotypes (such as plaque formation, gliosis reaction, and dystrophic neurites), leading to ameliorated memory performance in 5×FAD mice. RNA sequencing data further substantiated these findings, showing the enrichment of differentially expressed genes involved in biological processes including neurogenesis, cell proliferation, and amyloid protein formation. In conclusion, overexpressing Rbm8a in the dentate gyrus of 5×FAD mouse brains improved cognitive function by ameliorating amyloid-beta-associated pathological phenotypes and enhancing neurogenesis.

A systematic review and meta-analysis of tau phosphorylation in mouse models of familial Alzheimer's disease

Transgenic models of familial Alzheimer's disease (AD) serve as valuable tools for probing the molecular mechanisms associated with amyloid-beta (Aβ)-induced pathology. In this meta-analysis, we sought to evaluate levels of phosphorylated tau (p-tau) and explore potential age-related variations in tau hyperphosphorylation, within mouse models of AD. The PubMed and Scopus databases were searched for studies measuring soluble p-tau in 5xFAD, APPswe/PSEN1de9, J20 and APP23 mice. Data were extracted and analyzed using standardized procedures. For the 5xFAD model, the search yielded 36 studies eligible for meta-analysis. Levels of p-tau were higher in 5xFAD mice relative to control, a difference that was evident in both the carboxy-terminal (CT) and proline-rich (PR) domains of tau. Age negatively moderated the relationship between genotype and CT phosphorylated tau in studies using hybrid mice, female mice, and preparations from the neocortex. For the APPswe/PSEN1de9 model, the search yielded 27 studies. Analysis showed tau hyperphosphorylation in transgenic vs. control animals, evident in both the CT and PR regions of tau. Age positively moderated the relationship between genotype and PR domain phosphorylated tau in the neocortex of APPswe/PSEN1de9 mice. A meta-analysis was not performed for the J20 and APP23 models, due to the limited number of studies measuring p-tau levels in these mice (<10 studies). Although tau is hyperphosphorylated in both 5xFAD and APPswe/PSEN1de9 mice, the effects of ageing on p-tau are contingent upon the model being examined. These observations emphasize the importance of tailoring model selection to the appropriate disease stage when considering the relationship between Aβ and tau, and suggest that there are optimal intervention points for the administration of both anti-amyloid and anti-tau therapies.

Therapeutic Effects of the major alkaloid constituents of Evodia rutaecarpa in Alzheimer's disease

Since the report of Alzheimer's disease (AD) in 1907, it has garnered widespread attention due to its intricate pathogenic mechanisms, significant impact on patients' lives, and the substantial burden it places on society. Presently, effective treatments for AD remain elusive. Recent pharmacological studies on the traditional East Asian herb, Evodia rutaecarpa, have revealed that the bioactive alkaloid components within it can ameliorate AD-related cognitive impairments and neurological damage through various pathways, including anti-inflammatory, antioxidant, and anti-acetylcholinesterase activities. Consequently, this article provides an overview of the pharmacological effects and research status of the four main alkaloid components found in Evodia concerning AD. We hope this article will serve as a valuable reference for experimental and clinical research on the use of Evodia in AD prevention and treatment.

TNEA therapy promotes the autophagic degradation of NLRP3 inflammasome in a transgenic mouse model of Alzheimer's disease via TFEB/TFE3 activation

BACKGROUND

The impairment in the autophagy-lysosomal pathway (ALP) and the activation of NLR family pyrin domain containing 3 (NLRP3) inflammasome represent two molecular events leading to neurodegeneration and neuroinflammation in Alzheimer's disease (AD), a devastating neurodegenerative disorder without a cure. Previously we demonstrated the cognitive-enhancing effect of a combined electroacupuncture (EA) therapy termed TNEA in a transgenic mouse model of AD, involving activation of transcription factor EB (TFEB), a master regulator of ALP. However, whether and how TNEA inhibits NLRP3 inflammasome via TFEB-mediated ALP in AD remains to be investigated.

METHODS

5xFAD mice overexpressing amyloid-β (Aβ) were treated with TNEA or EA on its composing acupoints (GB13 and GV24). The changes in the signaling pathways regulating NLRP3 inflammasome, the association of NLRP3 inflammasome with ALP, and the roles of TFEB/TFE3 in mice brains were determined by immunoblots, immunohistochemistry and AAV-mediated knockdown assays.

RESULTS

TNEA inhibits the activation of NLRP3 inflammasome and the release of active interleukin 1β (IL1B) in the hippocampi of 5xFAD mice. Mechanistically, TNEA promoted the autophagic degradation of inflammasome components via activating both TFEB and TFE3 by modulating kinases including AMPK and AKT. The composing acupoints in TNEA showed synergistic effects on regulating these molecular events and memory improvement.

CONCLUSION

Our findings suggest that TNEA attenuates AD-associated memory impairment via promoting TFEB/TFE3-mediated autophagic clearance of Aβ and NLRP3 inflammasome, and partially reveal the molecular basis of combined acupoints therapy originated from ancient wisdom.

The pharmacokinetics profiles, pharmacological properties, and toxicological risks of dehydroevodiamine: A review

Dehydroevodiamine (DHE) is a quinazoline alkaloid isolated from Evodiae Fructus (EF, Wuzhuyu in Chinese, Rutaceae family), a well-known traditional Chinese medicine (TCM) which is clinically applied to treat headache, abdominal pain, menstrual pain, abdominal distension, vomiting, acid regurgitation, etc. Modern research demonstrates that DHE is one of the main components of EF. In recent years, DHE has received extensive attention due to its various pharmacological activities. This review is the first to comprehensively summarize the current studies on pharmacokinetics profiles, pharmacological properties, and toxicological risks of DHE in diverse diseases. Pharmacokinetic studies have shown that DHE has a relatively good oral absorption effect in the mean concentration curves in rat plasma and high absorption in the gastrointestinal tract. In addition, distribution re-absorption and enterohepatic circulation may lead to multiple blood concentration peaks of DHE in rat plasma. DHE possesses a wide spectrum of pharmacological properties in the central nervous system, cardiovascular system, and digestive system. Moreover, DHE has anti-inflammatory effects via downregulating pro-inflammatory cytokines and inflammatory mediators. Given the favorable pharmacological activity, DHE is expected to be a potential drug candidate for the treatment of Alzheimer's disease, chronic stress, amnesia, chronic atrophic gastritis, gastric ulcers, and rheumatoid arthritis. In addition, toxicity studies have suggested that DHE has proarrhythmic effects and can impair bile acid homeostasis without causing hepatotoxicity. However, further rigorous and well-designed studies are needed to elucidate the pharmacokinetics, pharmacological effects, potential biological mechanisms, and toxicity of DHE.

The novel estrogen receptor modulator STX attenuates Amyloid-β neurotoxicity in the 5XFAD mouse model of Alzheimer's disease

Based on previous evidence that the non-steroidal estrogen receptor modulator STX mitigates the effects of neurotoxic Amyloid-β (Aβ) in vitro, we have evaluated its neuroprotective benefits in a mouse model of Alzheimer's disease. Cohorts of 5XFAD mice, which begin to accumulate cerebral Aβ at two months of age, were treated with orally-administered STX starting at 6 months of age for two months. After behavioral testing to evaluate cognitive function, biochemical and immunohistochemical assays were used to analyze key markers of mitochondrial function and synaptic integrity. Oral STX treatment attenuated Aβ-associated mitochondrial toxicity and synaptic toxicity in the brain, as previously documented in cultured neurons. STX also moderately improved spatial memory in 5XFAD mice. In addition, STX reduced markers for reactive astrocytosis and microgliosis surrounding amyloid plaques, and also unexpectedly reduced overall levels of cerebral Aβ in the brain. The neuroprotective effects of STX were more robust in females than in males. These results suggest that STX may have therapeutic potential in Alzheimer's Disease.

Effect of cx-DHED on Abnormal Glucose Transporter Expression Induced by AD Pathologies in the 5xFAD Mouse Model

Alzheimer’s disease (AD) is a form of dementia associated with abnormal glucose metabolism resulting from amyloid-beta (Aβ) plaques and intracellular neurofibrillary tau protein tangles. In a previous study, we confirmed that carboxy-dehydroevodiamine∙HCl (cx-DHED), a derivative of DHED, was effective at improving cognitive impairment and reducing phosphorylated tau levels and synaptic loss in an AD mouse model. However, the specific mechanism of action of cx-DHED is unclear. In this study, we investigated how the cx-DHED attenuates AD pathologies in the 5xFAD mouse model, focusing particularly on abnormal glucose metabolism. We analyzed behavioral changes and AD pathologies in mice after intraperitoneal injection of cx-DHED for 2 months. As expected, cx-DHED reversed memory impairment and reduced Aβ plaques and astrocyte overexpression in the brains of 5xFAD mice. Interestingly, cx-DHED reversed the abnormal expression of glucose transporters in the brains of 5xFAD mice. In addition, otherwise low O-GlcNac levels increased, and the overactivity of phosphorylated GSK-3β decreased in the brains of cx-DHED-treated 5xFAD mice. Finally, the reduction in synaptic proteins was found to also improve by treatment with cx-DHED. Therefore, we specifically demonstrated the protective effects of cx-DHED against AD pathologies and suggest that cx-DHED may be a potential therapeutic drug for AD.

Medha Plus - A novel polyherbal formulation ameliorates cognitive behaviors and disease pathology in models of Alzheimer's disease

Alzheimer's disease (AD) is a multi-faceted neurodegenerative disorder that leads to drastic cognitive impairments culminating in death. Pathologically, it is characterized by amyloid-β (Aβ) plaques, neurofibrillary tangles and neurodegeneration in brain. Complete cure of AD remains elusive to date. Available synthetic drugs only provide symptomatic reliefs targeting single molecule, hence, are unable to address the multi-factorial aspects in AD pathogenesis. It is imperative to develop combinatorial drugs that address the multiple molecular targets in AD. We show a unique polyherbal formulation of Brahmi, Mandukaparni, Shankhpushpi, Yastimadhu, Kokilaksha and Shunthi called 'Medha Plus' (MP), conventionally used for improving memory and reducing anxiety, was able to ameliorate cognitive deficits and associated pathological hallmarks of AD. Viability assays revealed that MP prevented Aβ-induced loss of neurites as well as neuronal apoptosis in cellular models. An array of behavioral studies showed that MP was able to recover AD-associated memory deficits in both Aβ-injected rats and 5XFAD mice. Immunohistochemical studies further revealed that MP treatment reduced Aβ depositshpi and decreased apoptotic cell death in the hippocampus. Enzymatic assays demonstrated anti-oxidative and anti-acetyl cholinesterase properties of MP especially in hippocampus of Aβ-injected rats. An underlying improvement in synaptic plasticity was observed with MP treatment in 5XFAD mice along with an increased expression of phospho-Akt at serine 473 indicating a role of PI3K/Akt signaling in correcting these synaptic deficits. Thus, our strong experiment-driven approach shows that MP is an incredible combinatorial drug that targets multiple molecular targets with exemplary neuroprotective properties and is proposed for clinical trial.

MicroPET Imaging Assessment of Brain Tau and Amyloid Deposition in 6 × Tg Alzheimer’s Disease Model Mice

Alzheimer’s disease (AD) is characterized by the deposition of extracellular amyloid plaques and intracellular accumulation of neurofibrillary tangles (NFT). Amyloid beta (Aβ) and tau imaging are widely used for diagnosing and monitoring AD in clinical settings. We evaluated the pathology of a recently developed 6 × Tg − AD (6 × Tg) mouse model by crossbreeding 5 × FAD mice with mice expressing mutant (P301L) tau protein using micro-positron emission tomography (PET) image analysis. PET studies were performed in these 6 × Tg mice using [¹⁸F]Flutemetamol, which is an amyloid PET radiotracer; [¹⁸F]THK5351 and [¹⁸F]MK6240, which are tau PET radiotracers; moreover, [¹⁸F]DPA714, which is a translocator protein (TSPO) radiotracer, and comparisons were made with age-matched mice of their respective parental strains. We compared group differences in standardized uptake value ratio (SUVR), kinetic parameters, biodistribution, and histopathology. [¹⁸F]Flutemetamol images showed prominent cortical uptake and matched well with 6E10 staining images from 2-month-old 6 × Tg mice. [¹⁸F]Flutemetamol images showed a significant correlation with [¹⁸F]DPA714 in the cortex and hippocampus. [¹⁸F]THK5351 images revealed prominent hippocampal uptake and matched well with AT8 immunostaining images in 4-month-old 6 × Tg mice. Moreover, [¹⁸F]THK5351 images were confirmed using [¹⁸F]MK6240, which revealed significant correlations in the cortex and hippocampus. Uptake of [¹⁸F]THK5351 or [¹⁸F]MK6240 was highly correlated with [¹⁸F]Flutemetamol in 4-month-old 6 × Tg mice. In conclusion, PET imaging revealed significant age-related uptake of Aβ, tau, and TSPO in 6 × Tg mice, which was highly correlated with age-dependent pathology.

Inflammation and Rho-Associated Protein Kinase-Induced Brain Changes in Vascular Dementia

Patients with vascular dementia, caused by cerebral ischemia, experience long-term cognitive impairment due to the lack of effective treatment. The mechanisms of and treatments for vascular dementia have been investigated in various animal models; however, the insufficient information on gene expression changes that define pathological conditions hampers progress. To investigate the underlying mechanism of and facilitate treatment development for vascular dementia, we established a mouse model of chronic cerebral hypoperfusion, including bilateral carotid artery stenosis, by using microcoils, and elucidated the molecular pathway underlying vascular dementia development. Rho-associated protein kinase (ROCK) 1/2, which regulates cellular structure, and inflammatory cytokines (IL-1 and IL-6) were upregulated in the vascular dementia model. However, expression of claudin-5, which maintains the blood–brain barrier, and MAP2 as a nerve cell-specific factor, was decreased in the hippocampal region of the vascular dementia model. Thus, we revealed that ROCK pathway activation loosens the tight junction of the blood–brain barrier and increases the influx of inflammatory cytokines into the hippocampal region, leading to neuronal death and causing cognitive and emotional dysfunction. Our vascular dementia model allows effective study of the vascular dementia mechanism. Moreover, the ROCK pathway may be a target for vascular dementia treatment development in the future.

The potential anti-amyloidogenic candidate, SPA1413, for Alzheimer's disease

BACKGROUND AND PURPOSE

Recently, isoflavone derivatives have been shown to have neuroprotective effects against neurological disorders. For instance, genistein attenuated the neuroinflammation and amyloid-β accumulation in Alzheimer's disease animal models, suggesting the potential for use to prevent and treat Alzheimer's disease.

EXPERIMENTAL APPROACH

Here, 50 compounds, including isoflavone derivatives, were constructed and screened for the inhibitory effects on amyloid-β₄₂ fibrilization and oligomerization using the high-throughput screening formats of thioflavin T assay and multimer detection system, respectively. The potential neuroprotective effect of t3-(4-hydroxyphenyl)-2H-chromen-7-ol (SPA1413), also known as dehydroequol, idronoxil or phenoxodiol, was evaluated in cells and in 5xFAD (B6SJL) transgenic mouse, a model of Alzheimer's disease.

KEY RESULTS

SPA1413 had a potent inhibitory action on both amyloid-β fibrilization and oligomerization. In the cellular assay, SPA1413 prevented amyloid-β-induced cytotoxicity and reduced neuroinflammation. Remarkably, the oral administration of SPA1413 ameliorated cognitive impairment, decreased amyloid-β plaques and activated microglia in the brain of 5xFAD (B6SJL) transgenic mouse.

CONCLUSION AND IMPLICATIONS

Our results strongly support the repurposing of SPA1413, which has already received fast-track status from the US Food and Drug Administration (FDA) for cancer treatment, for the treatment of Alzheimer's disease due to its potent anti-amyloidogenic and anti-neuroinflammatory actions.

Therapeutic effects and potential mechanism of dehydroevodiamine on N-methyl-N'-nitro-N-nitrosoguanidine-induced chronic atrophic gastritis

BACKGROUNDS

Dehydroevodiamine (DHE) is a quinazoline alkaloid isolated from a Chinese herbal medicine, named Euodiae Fructus (Wu-Zhu-Yu in Chinese). This study aimed to investigate the therapeutic effects and potential mechanism of DHE on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced chronic atrophic gastritis (CAG) based on integrated approaches.

METHODS

Therapeutic effects of DHE on serum biochemical indices and histopathology of gastric tissue in MNNG-induced CAG rats were analyzed. MNNG-induced GES-1 human gastric epithelial cell injury model was established. Cell viability and proliferation was quantified by a cell counting kit-8 assay. Cell morphology and mitochondrial membrane potential (MMP) were detected by a high content screening (HCS) assay. Cell migration and invasion were detected by a Transwell chamber. Moreover, UHPLC-Q-TOF/MS was performed to investigate the potential metabolites and signaling pathway affecting the protective effects of DHE on MNNG-induced cell migration and invasion of GES-1. Furthermore, in view of the key role of angiogenesis in the transformation of inflammation and cancer, this study explored relative mRNA and protein expression levels of HIF-1α-mediated VEGF pathway in vivo and in vitro by RT-PCR and Western Blotting, respectively.

RESULTS

The results showed that the therapeutic effects of DHE on CAG rats were presented in down-regulation serum biochemical indices and alleviating histological damage of gastric tissue. Besides, DHE has an effect on increasing cell proliferation of GES-1 cells, ameliorating MNNG-induced gastric epithelial cell damage and mitochondrial dysfunction. In addition, DHE could inhibit MNNG induced migration and invasion of GES-1 cells. Cell metabolomics analyses showed that the protective effect of DHE on GES-1 cells is mainly associated with the regulation of inflammation metabolites and energy metabolism related pathways. It was found that DHE has a regulating effect on tumor angiogenesis and can inhibit the relative gene and protein expression of HIF-1α-mediated VEGF signaling pathway.

CONCLUSIONS

The present work highlighted the role of DHE ameliorated gastric injury in MNNG-induced CAG rats in vivo and GES-1 cell migration in vitro by inhibiting HIF-1α/VEGF angiogenesis pathway. These results suggest that DHE may be the effective components of Euodiae Fructus, which provides a new agent for the treatment of CAG.

Evaluation of the Therapeutic Effect of Lycoramine on Alzheimer's Disease in Mouse Model

BACKGROUND

Alzheimer's disease is one of the leading health problems characterized by the accumulation of Aβ and hyperphosphorylated tau that account for the senile plaque formations causing extensive cognitive decline. Many of the clinical diagnoses of Alzheimer's disease are made in the late stages, when the pathological changes have already progressed.

OBJECTIVE

The objective of this study is to evaluate the promising therapeutic effects of a natural compound, lycoramine, which has been shown to have therapeutic potential in several studies and to understand its mechanism of action on the molecular level via differential protein expression analyses.

METHODS

Lycoramine and galantamine, an FDA approved drug used in the treatment of mild to moderate AD, were administered to 12 month-old 5xFAD mice. Effects of the compounds were investigated by Morris water maze, immunohistochemistry and label- free differential protein expression analyses.

RESULTS

Here we demonstrated the reversal of cognitive decline via behavioral testing and the clearance of Aβ plaques. Proteomics analysis provided in-depth information on the statistically significant protein perturbations in the cortex, hippocampus and cerebellum sections to hypothesize the possible clearance mechanisms of the plaque formation and the molecular mechanism of the reversal of cognitive decline in a transgenic mouse model. Bioinformatics analyses showed altered molecular pathways that can be linked with the reversal of cognitive decline observed after lycoramine administration but not with galantamine.

CONCLUSION

Lycoramine shows therapeutic potential to halt and reverse cognitive decline at the late stages of disease progression, and holds great promise for the treatment of Alzheimer's disease.

Electroacupuncture ameliorates beta-amyloid pathology and cognitive impairment in Alzheimer disease via a novel mechanism involving activation of TFEB (transcription factor EB)

Alzheimer disease (AD) is the most prevalent neurodegenerative disorder leading to dementia in the elderly. Unfortunately, no cure for AD is available to date. Increasing evidence has proved the roles of misfolded protein aggregation due to impairment of the macroautophagy/autophagy-lysosomal pathway (ALP) in the pathogenesis of AD, and thus making TFEB (transcription factor EB), which orchestrates ALP, as a promising target for treating AD. As a complementary therapy, acupuncture or electroacupuncture (EA) has been commonly used for treating human diseases. Although the beneficial effects of acupuncture for AD have been primarily studied both pre-clinically and clinically, the real efficacy of acupuncture on AD remains inconclusive and the underlying mechanisms are largely unexplored. In this study, we demonstrated the cognitive-enhancing effect of three-needle EA (TNEA) in an animal model of AD with beta-amyloid (Aβ) pathology (5xFAD). TNEA reduced APP (amyloid beta (A4) precursor protein), C-terminal fragments (CTFs) of APP and Aβ load, and inhibited glial cell activation in the prefrontal cortex and hippocampus of 5xFAD. Mechanistically, TNEA activated TFEB via inhibiting the AKT-MAPK1-MTORC1 pathway, thus promoting ALP in the brains. Therefore, TNEA represents a promising acupuncture therapy for AD, via a novel mechanism involving TFEB activation.Abbreviations Aβ: β-amyloid; AD: Alzheimer disease; AIF1/IBA1: allograft inflammatory factor 1; AKT1: thymoma viral proto-oncogene 1; ALP: autophagy-lysosomal pathway; APP: amyloid beta (A4) precursor protein; BACE1: beta-site APP cleaving enzyme 1; CQ: chloroquine; CTFs: C-terminal fragments; CTSD: cathepsin D; EA: electroacupuncture; FC: fear conditioning; GFAP: glial fibrillary acidic protein; HI: hippocampus; LAMP1: lysosomal-associated membrane protein 1; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MAPK1/ERK2: mitogen-activated protein kinase 1; MAPT: microtubule-associated protein tau; MTORC1: mechanistic target of rapamycin kinase complex 1; MWM: Morris water maze; NFT: neurofibrillary tangles; PFC: prefrontal cortex; PSEN1: presenilin 1; SQSTM1/p62: sequestosome 1; TFEB: transcription factor EB; TNEA: three-needle electroacupuncture.

Spatial memory deficiency early in 6xTg Alzheimer's disease mouse model

Alzheimer’s disease (AD) is mainly characterized by the deposition of extracellular amyloid plaques and intracellular accumulation of neurofibrillary tangles (NFTs). While the recent 5xFAD AD mouse model exhibits many AD-related phenotypes and a relatively early and aggressive amyloid β production, it does not show NFTs. Here, we developed and evaluated a novel AD mouse model (6xTg-AD, 6xTg) by crossbreeding 5xFAD mice with mice expressing mutant (P301L) tau protein (MAPT). Through behavioral and histopathological tests, we analyzed cognitive changes and neuropathology in 6xTg mice compared to their respective parental strains according to age. Spatial memory deficits occurred in 6xTg mice at 2 months of age, earlier than they occurred in 5xFAD mice. Histopathological data revealed aggressive Aβ42 and p-tau accumulation in 6xTg mice. Microglial activation occurred in the cortex and hippocampus of 6xTg mice beginning at 2 months. In 6xTg model mice, the synaptic loss was observed in the cortex from 4 months of age and in the hippocampus from 6 months of age, and neuronal loss appeared in the cortex from 4 months of age and in the hippocampus 6 months of age, earlier than it is observed in the 5xFAD and JNPL3 models. These results showed that each pathological symptom appeared much faster than in their parental animal models. In conclusion, these novel 6xTg-AD mice might be an advanced animal model for studying AD, representing a promising approach to developing effective therapy.

A novel paradigm for assessing olfactory working memory capacity in mice

A decline in working memory (WM) capacity is suggested to be one of the earliest symptoms observed in Alzheimer's disease (AD). Although WM capacity is widely studied in healthy subjects and neuropsychiatric patients, few tasks are developed to measure this variation in rodents. The present study describes a novel olfactory working memory capacity (OWMC) task, which assesses the ability of mice to remember multiple odours. The task was divided into five phases: context adaptation, digging training, rule-learning for non-matching to a single-sample odour (NMSS), rule-learning for non-matching to multiple sample odours (NMMS) and capacity testing. During the capacity-testing phase, the WM capacity (number of odours that the mice could remember) remained stable (average capacity ranged from 6.11 to 7.00) across different testing sessions in C57 mice. As the memory load increased, the average errors of each capacity level increased and the percent correct gradually declined to chance level, which suggested a limited OWMC in C57 mice. Then, we assessed the OWMC of 5 × FAD transgenic mice, an animal model of AD. We found that the performance displayed no significant differences between young adult (3-month-old) 5 × FAD mice and wild-type (WT) mice during the NMSS phase and NMMS phase; however, during the capacity test with increasing load, we found that the OWMC of young adult 5 × FAD mice was significantly decreased compared with WT mice, and the average error was significantly increased while the percent correct was significantly reduced, which indicated an impairment of WM capacity at the early stage of AD in the 5 × FAD mice model. Finally, we found that FOS protein levels in the medial prefrontal cortex and entorhinal cortex after the capacity test were significantly lower in 5 × FAD than WT mice. In conclusion, we developed a novel paradigm to assess the capacity of olfactory WM in mice, and we found that OWMC was impaired in the early stage of AD.

In vivo Imaging With 18F-FDG- and 18F-Florbetaben-PET/MRI Detects Pathological Changes in the Brain of the Commonly Used 5XFAD Mouse Model of Alzheimer's Disease

Imaging biomarkers of Alzheimer's disease (AD) that are able to detect molecular changes in vivo and transgenic animal models mimicking AD pathologies are essential for the evaluation of new therapeutic strategies. Positron-emission tomography (PET) using either ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) or amyloid-tracers is a well-established, non-invasive tool in the clinical diagnostics of AD assessing two major pathological hallmarks. ¹⁸F-FDG-PET is able to detect early changes in cerebral glucose metabolism and amyloid-PET shows cerebral amyloid load. However, the suitability of ¹⁸F-FDG- and amyloid-PET in the widely used 5XFAD mouse model of AD is unclear as only a few studies on the use of PET biomarkers are available showing some conflicting results. The aim of this study was the evaluation of ¹⁸F-FDG-PET and amyloid-PET in 5XFAD mice in comparison to neurological deficits and neuropathological changes. Seven- and 12-month-old male 5XFAD mice showed a significant reduction in brain glucose metabolism in ¹⁸F-FDG-PET and amyloid-PET with ¹⁸F-Florbetaben demonstrated an increased cerebral amyloid deposition (n = 4-6 per group). Deficits in spatial reference memory were detected in 12-month-old 5XFAD mice in the Morris Water Maze (n = 10-12 per group). Furthermore, an increased plaque load and gliosis could be proven immunohistochemically in 5XFAD mice (n = 4-6 per group). PET biomarkers ¹⁸F-FDG and ¹⁸F-Florbetaben detected cerebral hypometabolism and increased plaque load even before the onset of severe memory deficits. Therefore, the 5XFAD mouse model of AD is well-suited for in vivo monitoring of AD pathologies and longitudinal testing of new therapeutic approaches.

Magnolol Ameliorates Behavioral Impairments and Neuropathology in a Transgenic Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is a common neurodegenerative disease characterized by progressive memory loss. Magnolol (MN), the main active ingredient of Magnolia officinalis, possesses anti-AD effects in several experimental models of AD. In this study, we aimed to explore whether MN could ameliorate the cognitive deficits in TgCRND8 transgenic mice and to elucidate its molecular mechanisms. Male TgCRND8 mice were orally administered with MN (20 and 40 mg/kg) daily for 4 consecutive months, followed by assessing the spatial learning and memory functions using the open-field, radial arm maze, and novel object recognition tests. The results demonstrated that MN (20 and 40 mg/kg) could markedly ameliorate the cognitive deficits in TgCRND8 mice. In addition, MN significantly increased the expression of postsynaptic density protein 93 (PSD93), PSD-95, synapsin-1, synaptotagmin-1, synaptophysin (SYN), and interleukin-10 (IL-10), while markedly reduced the protein levels of tumor necrosis factor alpha (TNF-α), IL-6, IL-1β, Aβ₄₀, and Aβ₄₂, and modulated the amyloid precursor protein (APP) processing and phosphorylation. Immunofluorescence showed that MN significantly suppressed the activation of microglia (Iba-1) and astrocytes (GFAP) in the hippocampus and cerebral cortex of TgCRND8 mice. Mechanistic studies revealed that MN could significantly increase the ratios of p-GSK-3β (Ser9)/GSK-3β, p-Akt (Ser473)/Akt, and p-NF-κB p65/NF-κB p65. These findings indicate that MN exerted cognitive deficits improving effects via suppressing neuroinflammation, amyloid pathology, and synaptic dysfunction through regulating the PI3K/Akt/GSK-3β and NF-κB pathways, suggesting that MN is a promising naturally occurring polyphenol worthy of further developing into a therapeutic agent for AD treatment.

VGF-derived peptide TLQP-21 modulates microglial function through C3aR1 signaling pathways and reduces neuropathology in 5xFAD mice

BACKGROUND

Multiomic studies by several groups in the NIH Accelerating Medicines Partnership for Alzheimer's Disease (AMP-AD) identified VGF as a major driver of Alzheimer's disease (AD), also finding that reduced VGF levels correlate with mean amyloid plaque density, Clinical Dementia Rating (CDR) and Braak scores. VGF-derived peptide TLQP-21 activates the complement C3a receptor-1 (C3aR1), predominantly expressed in the brain on microglia. However, it is unclear how mouse or human TLQP-21, which are not identical, modulate microglial function and/or AD progression.

METHODS

We performed phagocytic/migration assays and RNA sequencing on BV2 microglial cells and primary microglia isolated from wild-type or C3aR1-null mice following treatment with TLQP-21 or C3a super agonist (C3aSA). Effects of intracerebroventricular TLQP-21 delivery were evaluated in 5xFAD mice, a mouse amyloidosis model of AD. Finally, the human HMC3 microglial cell line was treated with human TLQP-21 to determine whether specific peptide functions are conserved from mouse to human.

RESULTS

We demonstrate that TLQP-21 increases motility and phagocytic capacity in murine BV2 microglial cells, and in primary wild-type but not in C3aR1-null murine microglia, which under basal conditions have impaired phagocytic function compared to wild-type. RNA sequencing of primary microglia revealed overlapping transcriptomic changes induced by treatment with TLQP-21 or C3a super agonist (C3aSA). There were no transcriptomic changes in C3aR1-null or wild-type microglia exposed to the mutant peptide TLQP-R21A, which does not activate C3aR1. Most of the C3aSA- and TLQP-21-induced differentially expressed genes were linked to cell migration and proliferation. Intracerebroventricular TLQP-21 administration for 28 days via implanted osmotic pump resulted in a reduction of amyloid plaques and associated dystrophic neurites and restored expression of subsets of Alzheimer-associated microglial genes. Finally, we found that human TLQP-21 activates human microglia in a fashion similar to activation of murine microglia by mouse TLQP-21.

CONCLUSIONS

These data provide molecular and functional evidence suggesting that mouse and human TLQP-21 modulate microglial function, with potential implications for the progression of AD-related neuropathology.