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Increasing evidence implicates endothelial dysfunction in the pathogenesis of Alzheimer's disease (AD). Nitric oxide (NO) derived from endothelial NO synthase (eNOS) is essential in maintaining cerebrovascular function and can modulate the production and clearance of amyloid beta (Aβ). APPswe/PSdE1 (APP/PS1) mice display age-related Aβ accumulation and memory deficits. In order to make the model more clinically relevant with an element of endothelial dysfunction, we generated APP/PS1/eNOS Show less

Metformin (MET) is among the most consumed drugs around the world, and thus, it is considered the uppermost drug in mass discharged into water settings. Nonetheless, data about the deleterious consequences of MET on water organisms are still scarce and require further investigation. Herein, we aimed to establish whether or not chronic exposure to MET (1, 20, and 40 μg/L) may alter the swimming behavior and induce neurotoxicity in Danio rerio adults. After 4 months of exposure, MET-exposed fish exhibited less swimming activity when compared to control fish. Moreover, compared with the control group, MET significantly inhibited the activity of AChE and induced oxidative damage in the brain of fish. Concerning gene expression, MET significantly upregulated the expression of Nrf1, Nrf2, BAX, p53, BACE1, APP, PSEN1, and downregulated CASP3 and CASP9. Although MET did not overexpress the CASP3 gene, we saw a meaningful rise in the activity of this enzyme in the blood of fish exposed to MET compared to the control group, which we then confirmed by a high number of apoptotic cells in the TUNEL assay. Our findings demonstrate that chronic exposure to MET may impair fish swimming behavior, making them more vulnerable to predators. Show less

Type2 diabetes mellitus is a progressive metabolic disorder characterized by β-cell dysfunction with the increase in hepatic glucose synthesis and insulin resistance which leads to microvascular complications like diabetic encephalopathy that impairs cognitive dysfunctions, and dementia. The green and leafy vegetables of Show less

We determined the effectiveness of absolute binding free energy (ABFE) calculations to refine the selection of active compounds in virtual compound screening, a setting where the more commonly used relative binding free energy approach is not readily applicable. To do this, we conducted baseline docking calculations of structurally diverse compounds in the DUD-E database for three targets, BACE1, CDK2 and thrombin, followed by ABFE calculations for compounds with high docking scores. The docking calculations alone achieved solid enrichment of active compounds over decoys. Encouragingly, the ABFE calculations then improved on this baseline. Analysis of the results emphasizes the importance of establishing high quality ligand poses as starting points for ABFE calculations, a nontrivial goal when processing a library of diverse compounds without informative co-crystal structures. Overall, our results suggest that ABFE calculations can play a valuable role in the drug discovery process. Show less

Alzheimer disease (AD), a progressive neurodegenerative disorder, is mainly caused by the interaction of genetic and environmental factors. The impact of environmental factors on the genetic mutation in the amyloid precursor protein (APP) is not well characterized. We hypothesized that endoplasmic reticulum (ER) stress would promote disease for the patient carrying the APP D678H mutation. Therefore, we analyzed the impact of a familial AD mutation on amyloid precursor protein (APP D678H) under ER stress. Induced pluripotent stem cells (iPSCs) from APP D678H mutant carrier was differentiated into neurons, which were then analyzed for AD-like changes. Immunocytochemistry and whole-cell patch-clamp recording revealed that the derived neurons on day 28 after differentiation showed neuronal markers and electrophysiological properties similar to those of mature neurons. However, the APP D678H mutant neurons did not have significant alterations in the levels of amyloid-β (Aβ) and phosphorylated tau (pTau) compared to its isogenic wild-type neurons. Only under ER stress, the neurons with the APP D678H mutation had more Aβ and pTau via immune detection assays. The higher level of Aβ in the APP D678H mutant neurons was probably due to the increased level of β-site APP cleaving enzyme (BACE1) and decreased level of Aβ-degrading enzymes under ER stress. Increased Aβ and pTau under ER stress reduced the N-methyl-D-aspartate receptor (NMDAR) in Western blot analysis and altered electrophysiological properties in the mutant neurons. Our study provides evidence that the interaction between genetic mutation and ER stress would induce AD-like changes. Cover Image for this issue: https://doi.org/10.1111/jnc.15420. Show less

We profile genome-wide histone 3 lysine 27 acetylation (H3K27ac) of 3 major brain cell types from hippocampus and dorsolateral prefrontal cortex (dlPFC) of subjects with and without Alzheimer's Disease (AD). We confirm that single nucleotide polymorphisms (SNPs) associated with late onset AD (LOAD) show a strong tendency to reside in microglia-specific gene regulatory elements. Despite this significant colocalization, we find that microglia harbor more acetylation changes associated with age than with amyloid-β (Aβ) load. In contrast, we detect that an oligodendrocyte-enriched glial (OEG) population contains the majority of differentially acetylated peaks associated with Aβ load. These differential peaks reside near both early onset risk genes ( Show less

All clinical BACE1-inhibitor trials for the treatment of Alzheimer's Disease (AD) have failed due to insufficient efficacy or side effects like worsening of cognitive symptoms. However, the scientific evidence to date suggests that BACE1-inhibition could be an effective preventative measure if applied prior to the accumulation of amyloid-beta (Aβ)-peptide and resultant impairment of synaptic function. Preclinical studies have associated BACE1-inhibition-induced cognitive deficits with decreased dendritic spine density. Therefore, we investigated dose-dependent effects of BACE1-inhibition on hippocampal dendritic spine dynamics in an APP knock-in mouse line for the first time. We conducted Show less

Alzheimer's disease (AD) is a devastating neurodegenerative disorder without a cure. Hence, developing an effective treatment or protective agent is crucial for public health. The present study aims to characterize orange peel extract (OPE) through in vitro and in silico studies. Furthermore, it examines the protective effect of OPE against experimentally-induced Alzheimer's disease in rats. The total phenolic and flavonoid content of OPE was 255.86 ± 1.77 and 52.06 ± 1.74 (mg/100 g), respectively. Gallic acid, the common polyphenol in OPE detected by HPLC was 3388.60 μg/100 g. OPE antioxidant IC Show less

Alzheimer's disease (AD) is a neurodegenerative disease characterized by memory loss and cognitive dysfunction in the elderly, with amyloid-beta (Aβ) deposition and hyperphosphorylation of tau protein as the main pathological feature. Nuclear factor 2 (Nrf2) is a transcription factor that primarily exists in the cytosol of hippocampal neurons, and it is considered as an important regulator of autophagy, oxidative stress, and inflammation. Total saikosaponins (TS) is the main bioactive component of Show less

Previous studies have shown that ovarian estrogens are involved in the occurrence and pathology of Alzheimer's disease (AD) through regulation on hippocampal synaptic plasticity and spatial memory; however, the underlying mechanisms have not yet been elucidated at the genomic scale. In this study, we established the postmenopausal estrogen-deficient model by ovariectomy (OVX). Then, we used high-throughput Affymetrix Clariom transcriptomics and found 143 differentially expressed genes in the hippocampus of OVX mice with the absolute fold change ≥ 1.5 and P < 0.05. GO analysis showed that the highest enrichment was seen in long-term memory. Combined with the response to steroid hormone enrichment and GeneMANIA network prediction, the serum and glucocorticoid-regulated kinase 1 gene (Sgk1) was found to be the most potent candidate for ovarian estrogenic regulation. Sgk1 overexpression viral vectors (oSgk1) were then constructed and injected into the hippocampus of OVX mice. Morris water maze test revealed that the impaired spatial learning and memory induced by OVX was rescued by Sgk1 overexpression. Additionally, the altered expression of synaptic proteins and actin remodeling proteins and changes in CA1 spine density and synapse density induced by OVX were also significantly reversed by oSgk1. Moreover, the OVX-induced increase in Aβ-producing BACE1 and Aβ and the decrease in insulin degrading enzyme were significantly reversed by oSgk1. The above results show that multiple pathways and genes are involved in ovarian estrogenic regulation of the function of the hippocampus, among which Sgk1 may be a novel potent target against estrogen-sensitive hippocampal dysfunctions, such as Aβ-initiated AD. Show less

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by behavioral and psychological symptoms in addition to cognitive impairment and loss of memory. The exact pathogenesis and genetic background of AD are unclear and there remains no effective treatment option. Sarcosine, an n-methyl derivative of glycine, showed a promising therapeutic strategy for some cognitive disorders. To our knowledge, the impacts of sarcosine supplementation against AD have not yet been elucidated. Therefore, we aimed to determine the neuroprotective potential of sarcosine in Show less

The β-site Amyloid precursor protein Cleaving Enzyme 1 (BACE1) is an extensively studied therapeutic target for Alzheimer's disease (AD), owing to its role in the production of neurotoxic amyloid beta (Aβ) peptides. However, despite numerous BACE1 inhibitors entering clinical trials, none have successfully improved AD pathogenesis, despite effectively lowering Aβ concentrations. This can, in part, be attributed to an incomplete understanding of BACE1, including its physiological functions and substrate specificity. We propose that BACE1 has additional important physiological functions, mediated through substrates still to be identified. Thus, to address this, we computationally analysed a list of 533 BACE1 dependent proteins, identified from the literature, for potential BACE1 substrates, and compared them against proteins differentially expressed in AD. We identified 15 novel BACE1 substrates that were specifically altered in AD. To confirm our analysis, we validated Protein tyrosine phosphatase receptor type D (PTPRD) and Netrin receptor DCC (DCC) using Western blotting. These findings shed light on the BACE1 inhibitor failings and could enable the design of substrate-specific inhibitors to target alternative BACE1 substrates. Furthermore, it gives us a greater understanding of the roles of BACE1 and its dysfunction in AD. Show less

D-galactose (D-gal) induced senescence in rodents is a widely used model for assessment of molecules affecting brain ageing. Chronic administration of D-gal causes neuroinflammation leading to cognitive deficit and memory impairment which represent Alzheimer's dementia. In present study, we investigated the neuroprotective effects of the natural phenol, p-Coumaric acid (PCA) and its underlying mechanism in the chronic D-gal treated mice. Subcutaneous administration of D-gal (150 mg/kg) to Swiss albino mice for 42 consecutive days resulted in cognitive impairment as observed in Morris water maize (MWM) and Y maze test, which was ameliorated by concurrent treatment with PCA (80 mg/kg, and 100 mg/kg, p.o.). Importantly, PCA treatment attenuated the D-gal induced oxidative stress and significantly inhibited acetylcholinesterase (AChE) activity in mice brain. Furthermore, PCA treatment significantly lowered levels of inflammatory marker nuclear factor kappa B (NFκB) and reduced levels of proapoptotic enzyme caspase3. We also observed that PCA treatment exhibited β-secretase enzyme (BACE1) inhibitory effect. However, our results revealed that PCA treatment failed to decrease the level of advanced glycation end products both in vitro and in vivo. Taken together, current study demonstrated the significant neuroprotective effect of PCA against D-gal induced oxidative stress, neuroinflammation, cognitive impairment and apoptosis. Show less

Plants have immensely contributed to the drug discovery for neurodegenerative diseases. Herein, we undertook the phytochemical investigation of Nardostachys jatamansi (D.Don) DC. rhizomes followed by semisynthetic modifications to discover cholinesterase (ChE) and beta-site amyloid precursor protein cleaving enzyme 1 (BACE-1) inhibitors. The 8-acetyl-7-hydroxycoumarin isolated from the bioactive extract moderately inhibits acetylcholinesterase (AChE) and BACE-1 with IC Show less

Oxidative stress (OS) and c-Jun N-terminal kinase (JNK) are both key indicators implicated in neuro-inflammatory signalling pathways and their respective neurodegenerative diseases. Drugs targeting these factors can be considered as suitable candidates for treatment of neuronal dysfunction and memory impairment. The present study encompasses beneficial effects of a naturally occurring triterpenoid, friedelin, against scopolamine-induced oxidative stress and neurodegenerative pathologies in mice models. The treated animals were subjected to behavioural tests i.e., Y-maze and Morris water maze (MWM) for memory dysfunction. The underlying mechanism was determined via western blotting, antioxidant enzymes and lipid profile analyses. Molecular docking studies were carried out to predict the binding modes of friedelin in the binding pocket of p-JNK protein. The results reveal that scopolamine caused oxidative stress by (1) inhibiting catalase (CAT), peroxidase enzyme (POD), superoxide dismutase (SOD), and reduced glutathione enzyme (GSH); (2) the up-regulation of thiobarbituric acid reactive substances (TBARS) in mice brain; and (3) affecting the neuronal synapse (both pre- and post-synapse) followed by associated memory dysfunction. In contrast, friedelin administration not only abolished scopolamine-induced oxidative stress, glial cell activation, and neuro-inflammation but also inhibited p-JNK and NF-κB and their downstream signaling molecules. Moreover, friedelin administration improved neuronal synapse and reversed scopolamine-induced memory impairment accompanied by the inhibition of β-secretase enzyme (BACE-1) to halt amyloidogenic pathways of amyloid-β production. In summary, all of the results show that friedelin is a potent naturally isolated neuro-therapeutic agent to reverse scopolamine-induced neuropathology, which is characteristic of Alzheimer's disease. Show less

Cinnamomum verum J. Presl. (Lauraceae), Myrtus communis L. (Myrtaceae), Ruta graveolens L. (Rutaaceae), Anethum graveolens L. (Apiaceae), Myristica fragrans Houtt. (Myristicaceae), and Crocus sativus L. (Iridaceae) have been recommended for improvement of memory via inhalation, in Iranian Traditional Medicine (ITM). In this respect, the essential oils (EOs) from those plants were obtained and evaluated for cholinesterase (ChE) inhibitory activity as ChE inhibitors are the available drugs in the treatment of Alzheimer's disease (AD). EOs obtained from the plants under investigation, were evaluated for their potential to inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in vitro based on the modified Ellman's method. The most potent EO was candidate for the investigation of its beta-secretase 1 (BACE1) inhibitory activity and neuroprotectivity. Among all EOs, C. verum demonstrated the most potent activity toward AChE and BChE with IC Potent BChE inhibitory activity of C. verum EO can be considered in the development of cinnamon based dietary supplements for the management of patients with advanced AD. Show less

Aberrant cleavage of the transmembrane protein, amyloid-beta precursor protein (ABPP), results in the overproduction of amyloid-beta (AB) peptides which can form senile plaques in the brain. These plaques can get lodged within synapses and disrupt neuronal communication ultimately leading to rampant neuron death. The rate-limiting enzyme in AB production is beta-site ABPP cleaving enzyme 1 (BACE1). In females, estrogen loss is associated with increases in AB and BACE1 content and activity. Exercise is known to have anti-amyloidogenic effects and may be able to alter BACE1 in cases of ovarian hormone depletion. This study aimed to examine the effects of physical activity on BACE1 in intact and ovariectomized female mice. Female C57BL/6 mice (24 weeks old) underwent bilateral ovariectomy (OVX; n=20) or SHAM surgery (SHAM; n=20). Mice were assigned to one of four groups (n=10/group) for 8 weeks: (1) sham (SHAM), (2) sham with a wheel (SHAM VWR), (3) ovariectomized (OVX), or (4) ovariectomized with a wheel (OVX VWR). Novel object recognition testing demonstrated that OVX mice had a lower percentage of novel object investigation time compared to SHAM. OVX mice also had higher prefrontal cortex BACE1 activity compared to SHAM (p<0.0001), while the OVX+VWR activity was not different from SHAM. Our results demonstrate that voluntary wheel running in an ovariectomized model prevented increases in BACE1 activity, maintained memory recall, and may provide a method of slowing the progression of Alzheimer's disease. Show less

Alzheimer's disease is a global public health problem and the most common form of dementia. Due to the failure of many single therapies targeting the two hallmarks, Aβ and Tau, and the multifactorial etiology of AD, there is now more and more interest in nutraceutical agents with multiple effects such as Show less

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder and the most common cause of dementia in the elderly. The complexity of AD has hindered the development of either a cure or a disease-modifying therapy to halt the disease progression. Numerous hypotheses were presented in order to explain the mechanisms underlying the pathogenesis of AD. Introduced in 1992, the "Amyloid Cascade Hypothesis" had a huge impact on the field and inspired the rise of various drug candidates, especially amyloid-beta (Aβ)-directed drugs; including beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitors. Adopted by a number of pharmaceutical companies, the development of BACE1 inhibitors has gained momentum in the past decade with promising results from experimental and early clinical-phase studies. Nevertheless, nearly all BACE1 inhibitors failed in later phases of clinical trials, due to safety and/or efficacy issues, and others were discontinued early in favor of second-generation small-molecule candidates. This paper aims to provide a comprehensive review of all BACE1 inhibitors to ever reach clinical trials, and we discuss the challenges and different perspectives on whether BACE1 inhibitors are to be reconsidered or revitalized in the future. Show less

Being the most common form of dementia, Alzheimer's disease (AD) has a series of modifiable risk factors, including metal ions represented by aluminium. Aluminium (Al) exhibits its neurotoxic effects, especially mainly by affecting amyloid-β protein (Aβ) aggregation and Tau hyperphosphorylation. As reported in our previous study, the combination of Alpinia Oxyphylla Fructus and Schisandra Chinensis Fructus (AS) had a neuroprotective effect. This study aimed to evaluate the anti-AD effect of AS and the mechanism by which AS reduces the neurotoxic effect of Al. Firstly, we used aluminium-maltol (Al(mal) Show less

Neuritic plaques are one of the major pathological hallmarks of Alzheimer's disease. They are formed by the aggregation of extracellular amyloid-β protein (Aβ), which is derived from the sequential cleavage of amyloid-β precursor protein (APP) by β- and γ-secretase. BACE1 is the main β-secretase in the pathogenic process of Alzheimer's disease, which is believed to be a rate-limiting step of Aβ production. Presenilin 1 (PS1) is the active center of the γ-secretase that participates in the APP hydrolysis process. Mutations in the PS1 gene ( Show less

The interrelationships between neuronal viability, synaptic integrity, and microglial responses remain in infancy. In dealing with the question, we induced a stretch injury to evaluate the mechanical effects of trauma on rat primary cortical neurons and BV2 microglial cells in a transwell culture system. The viability of primary neurons and BV2 cells was determined by MTT. Synaptic integrity was evaluated by determining the expression of beta-secretase 1 (BACE1), amyloid-beta (Aβ), microtubule-associated protein 2 (MAP2), and synaptophysin (vehicle protein). Both CD16/32-positive (CD16/32 Show less

Acute and long-term paraquat (PQ) exposure produces hippocampal neurodegeneration and cognition decline. Although some mechanisms involved in these effects were found, the rest are unknown. PQ treatment, for 1 and 14 days, upregulated interferon-gamma signaling, which reduced insulin levels and downregulated the insulin pathway through phosphorylated-c-Jun N-terminal-kinase upregulation, increasing glucose levels and the production of Aβ Show less

Alzheimer's disease (AD) is a common neurodegenerative disorder with progressive cognitive impairment in the elderly. Beta-amyloid (Aβ) formation and its accumulation in the brain constitute one of the pathological hallmarks of AD. Until now, how to modulate Aβ formation in hippocampal neurons remains a big challenge. Herein, we investigated whether the exosomal transfer of microRNA (miR) relates to amyloid pathology in the recipient neuron cells. We isolated circulating small extracellular vesicles (sEVs) from AD patients and healthy controls, determined the miR-342-5p level in the sEVs by RT-PCR, and evaluated its diagnostic performance in AD. Then, we took advantage of biomolecular assays to estimate the role of miR-342-5p in modulating the amyloid pathway, including amyloid precursor protein (APP), beta-site APP cleaving enzyme 1 (BACE1), and Aβ42. Furthermore, we subjected HT22 cells to the sEVs from the hippocampal tissues of transgenic APP mice (Exo-APP) or C57BL/6 littermates (Exo-CTL), and the Exo-APP enriched with miR-342-5p mimics or the control to assess the effect of the sEVs' delivery of miR-342-5p on Aβ formation. We observed a lower level of miR-342-5p in the circulating sEVs from AD patients compared with healthy controls. MiR-342-5p participated in Aβ formation by modulating BACE1 expression, specifically binding its 3'-untranslated region (UTR) sequence. Exo-APP distinctly promoted Aβ42 formation in the recipient cells compared to Exo-CTL. Intriguingly, miR-342-5p enrichment in Exo-APP ameliorated amyloid pathology in the recipient cells. Our study indicated that miR-342-5p was dysregulated in human circulating sEVs from AD patients; sEV transfer of miR-342-5p ameliorates Aβ formation by modulating BACE1 expression. These findings highlight the promising potential of exosomal miRNAs in AD clinical therapy. Show less