Protective Effects of 6-(Methylsulfinyl)hexyl Isothiocyanate on Aβ1-42-Induced Cognitive Deficit, Oxidative Stress, Inflammation, and Apoptosis in Mice

The Unfolded Protein Response in a Murine Model of Alzheimer's Disease: Looking for Predictors

Alzheimer's disease (AD) represents the most frequent type of dementia worldwide, and aging is the most important risk factor for the sporadic form of the pathology. The endoplasmic reticulum (ER), the main cellular actor involved in proteostasis, appears significantly compromised in AD due to the accumulation of the β-amyloid (Aβ) protein and the phosphorylated Tau protein. Increasing protein misfolding activates a specific cellular response known as Unfolded Protein Response (UPR), which orchestrates the recovery of ER function. The aim of the present study was to investigate the role of UPR in a murine model of AD induced by intracerebroventricular (i.c.v.) injection of Aβ1-42 oligomers at 3 or 18 months. The oligomer injection in aged animals induced memory impairment, oxidative stress, and the depletion of glutathione reserve. Furthermore, the RNA sequencing and the bioinformatic analysis performed showed the enrichment of several pathways involved in neurodegeneration and protein regulations. The analysis highlighted the significant dysregulation of the protein kinase RNA-like ER kinase (PERK), inositol-requiring protein 1α (IRE1α) and activating transcription factor 6 (ATF-6). In turn, ER stress affected the PI3K/Akt/Gsk3β and MAPK/ERK pathways, highlighting Mapkapk5 as a potential marker, whose regulation could lead to the definition of new pharmacological and neuroprotective strategies to counteract AD.

Dietary glucosinolates derived isothiocyanates: chemical properties, metabolism and their potential in prevention of Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent form of dementia affecting millions of people worldwide. It is a progressive, irreversible, and incurable neurodegenerative disorder that disrupts the synaptic communication between millions of neurons, resulting in neuronal death and functional loss due to the abnormal accumulation of two naturally occurring proteins, amyloid β (Aβ) and tau. According to the 2018 World Alzheimer's Report, there is no single case of an Alzheimer's survivor; even 1 in 3 people die from Alzheimer's disease, and it is a growing epidemic across the globe fruits and vegetables rich in glucosinolates (GLCs), the precursors of isothiocyanates (ITCs), have long been known for their pharmacological properties and recently attracted increased interest for the possible prevention and treatment of neurodegenerative diseases. Epidemiological evidence from systematic research findings and clinical trials suggests that nutritional and functional dietary isothiocyanates interfere with the molecular cascades of Alzheimer's disease pathogenesis and prevent neurons from functional loss. The aim of this review is to explore the role of glucosinolates derived isothiocyanates in various molecular mechanisms involved in the progression of Alzheimer's disease and their potential in the prevention and treatment of Alzheimer's disease. It also covers the chemical diversity of isothiocyanates and their detailed mechanisms of action as reported by various in vitro and in vivo studies. Further clinical studies are necessary to evaluate their pharmacokinetic parameters and effectiveness in humans.

Therapeutic Candidates for Alzheimer's Disease: Saponins

Drug development for Alzheimer's disease, the leading cause of dementia, has been a long-standing challenge. Saponins, which are steroid or triterpenoid glycosides with various pharmacological activities, have displayed therapeutic potential in treating Alzheimer's disease. In a comprehensive review of the literature from May 2007 to May 2023, we identified 63 references involving 40 different types of saponins that have been studied for their effects on Alzheimer's disease. These studies suggest that saponins have the potential to ameliorate Alzheimer's disease by reducing amyloid beta peptide deposition, inhibiting tau phosphorylation, modulating oxidative stress, reducing inflammation, and antiapoptosis. Most intriguingly, ginsenoside Rg1 and pseudoginsenoside-F11 possess these important pharmacological properties and show the best promise for the treatment of Alzheimer's disease. This review provides a summary and classification of common saponins that have been studied for their therapeutic potential in Alzheimer's disease, showcasing their underlying mechanisms. This highlights the promising potential of saponins for the treatment of Alzheimer's disease.

Preconditioning adipose-derived mesenchymal stem cells with dimethyl fumarate promotes their therapeutic efficacy in the brain tissues of rats with Alzheimer's disease

AIM

Transplantation of mesenchymal stem cell (MSC) has been suggested to be a promising method for treating neurodegenerative conditions, including Alzheimer's disease (AD). However, the poor survival rate of transplanted MSCs has limited their therapeutic application. This study aimed to evaluate whether preconditioning MSCs with dimethyl fumarate (DMF), a Nrf2 inducer, could enhance MSC therapeutic efficacy in an amyloid-β (Aβ_1-42)-induced AD rat model.

METHODS

The survival and antioxidant capacity of MSCs treated with DMF were assessed in vitro. Aβ_1-42 intrahippocampal injection was used to create a rat model of AD. Following the transplantation of MSCs preconditioned with DMF and using the Morris blue maze test, spatial learning and memory were assessed. Using RT-qPCR, we evaluated the gene expression related to apoptosis and neurotrophins in the hippocampus region.

RESULTS

Treatment with DMF enhanced cell survival and Nrf2 protein expression in MSCs in vitro. Preconditioning with DMF also enhanced the efficacy of transplanted MSCs in rescuing learning and spatial memory deficits in Aβ-AD rats. Besides, DMF preconditioning enhanced the neuroprotective effect of transplanted MSCs in the hippocampus of rats treated with Aβ_1-42 by decreasing the expression of apoptotic markers (Bax, caspase 3, and cytochrome c), and elevating the expression of the anti-apoptotic marker Bcl2 and neurotrophins, including BDNF and NGF.

CONCLUSION

Preconditioning MSCs with DMF boosted the therapeutic efficacy of these cells; therefore, it could serve as a targeted strategy for increasing the therapeutic efficacy of MSCs in treating neurodegenerative disorders, including AD.

Clinical effects of wasabi extract containing 6-MSITC on myalgic encephalomyelitis/chronic fatigue syndrome: an open-label trial

BACKGROUND

Wasabi (Eutrema japonicum) is a common pungent spice used in Japan. 6-Methylsulfinylhexyl isothiocyanate (6-MSITC) found in the rhizome of wasabi has been shown to have anti-inflammatory and antioxidant effects, as well as improve neuroinflammation and memory. Therefore, we hypothesized that these effects would be beneficial for treating myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The present study was conducted to investigate the effectiveness of wasabi extract containing 6-MSITC on ME/CFS in an open-label trial.

METHODS

Fifteen patients (3 males, 12 females, 20-58 years old) were orally administered wasabi extract (9.6 mg of 6-MSITC/day) for 12 weeks. The following parameters and test results were compared pre- and post-treatment: performance status (PS), self-rating questionnaires, pressure pain threshold (PPT) on the occiput, Trail Making test-A (TMT-A), and hemodynamic patterns determined by an active standing test.

RESULTS

After treatment with 6-MSITC, PS improved significantly (p = 0.001). Although the scores on the 11-item Chalder Fatigue scale (CFS-11) and numerical rating scale (NRS) of fatigue did not show significant changes, subjective symptoms improved significantly, including headache frequency (4.1 to 3.0 times/week, p = 0.001) and myalgia (4.1 to 2.4 times/week, p = 0.019), NRS brain fog scores (5.7 to 4.5, p = 0.011), difficulty finding appropriate words (4.8 to 3.7, p = 0.015), photophobia (4.8 to 3.5, p = 0.008), and the Profile of Mood Status vigor score (46.9 to 50.0, p = 0.045). The PPT of the right occiput (17.3 to 21.3 kPa, p = 0.01) and TMT-A scores (53.0 to 38.1 s, p = 0.007) also changed, suggesting reduced pain sensitivity, and improved cognitive function, respectively. Orthostatic patterns determined by a standing test did not show remarkable changes. There were no serious adverse reactions.

CONCLUSION

This study suggests that 6-MSITC improves PS as well as subjective symptoms such as pain and cognitive dysfunction, and psychological vitality of patients with ME/CFS. It also improved cognitive performance and increased pain thresholds in these patients. 6-MSITC may be a promising therapeutic option especially for improving cognitive dysfunction associated with ME/CFS.

Effects of Subtoxic Concentrations of Atrazine, Cypermethrin, and Vinclozolin on microRNA-Mediated PI3K/Akt/mTOR Signaling in SH-SY5Y Cells

Endocrine-disrupting chemicals (EDCs) are different natural and synthetic chemicals that may interfere with several mechanisms of the endocrine system producing adverse developmental, metabolic, reproductive, and neurological effects in both human beings and wildlife. Among pesticides, numerous chemicals have been identified as EDCs. MicroRNAs (miRNAs) can regulate gene expression, making fine adjustments in mRNA abundance and regulating proteostasis. We hypothesized that exposure to low doses of atrazine, cypermethrin, and vinclozolin may lead to effects on miRNA expression in SH-SY5Y cells. In particular, the exposure of SH-SY5Y cells to subtoxic concentrations of vinclozolin is able to downregulate miR-29b-3p expression leading to the increase in the related gene expression of ADAM12 and CDK6, which may promote a pro-oncogenic response through the activation of the PI3K/Akt/mTOR pathway and counteracting p53 activity. A better understanding of the molecular mechanisms of EDCs could provide important insight into their role in human disease.

Involvement of AMP-activated Protein Kinase α/Nuclear Factor (Erythroid-derived 2) Like 2-iniatived Signaling Pathway in Cytoprotective Effects of Wasabi 6-(Methylsulfinyl) Hexyl Isothiocyanate

6-(Methylsulfinyl) hexyl isothiocyanate (6-MSITC) is an active ingredient present in Wasabi, which is a popular pungent spice used in Japanese cuisine. Our previous studies suggested that the primary antioxidant activity of 6-MSITC may link to other biological activity. This study aimed to clarify how the antioxidant activity of 6-MSITC contributes to preventing overloaded lipid stress in hepatic cell model. HepG2 cells were treated with 6-MSITC at defined concentrations and times in normal medium or in combined fatty acids (CFA) medium, and the targeted proteins were detected by Western blotting. The kinetic data revealed that 6-MSITC activated AMP-activated protein kinase α (AMPKα) and nuclear factor (erythroid-derived 2) like 2 (Nrf2), and then enhanced the protein expression of Forkhead box protein O1 (FOXO1) and Sirtuin1 as well as that of the Nrf2 target proteins, NAD(P)H:quinone oxidoreductase 1 (NQO1) and heme oxygenase (HO-1). Furthermore, lipid metabolic stress was mimicked in HepG2 cells by overloading CFA. 6-MSITC significantly alleviated CFA-induced formation of thiobarbituric acid reactive substances and fat accumulation. Signaling analysis data revealed that 6-MSITC enhanced phosphorylation of AMPKα, upregulated the expression of Nrf2, NQO1, heme oxygenase 1, FOXO1, and Siruin1, and downregulated the expression of PPARα. Taken together, our results suggested that the AMPKα/Nrf2-mediated signaling pathways might be involved in the cytoprotective effects of Wasabi 6-MSITC against metabolic lipid stress.

Novel Prenylated Indole Alkaloids with Neuroprotection on SH-SY5Y Cells against Oxidative Stress Targeting Keap1–Nrf2

Oxidative stress has been implicated in the etiology of Parkinson’s disease (PD). Molecules non-covalently binding to the Keap1–Nrf2 complex could be a promising therapeutic approach for PD. Herein, two novel prenylated indole alkaloids asperpenazine (1), and asperpendoline (2) with a scarce skeleton of pyrimido[1,6-a]indole were discovered from the co-cultivated fungi of Aspergillus ochraceus MCCC 3A00521 and Penicillium sp. HUBU 0120. Compound 2 exhibited potential neuroprotective activity on SH-SY5Y cells against oxidative stress. Molecular mechanism research demonstrated that 2 inhibited Keap1 expression, resulting in the translocation of Nrf2 from the cytoplasm to the nucleus, activating the downstream genes expression of HO-1 and NQO1, leading to the reduction in reactive oxygen species (ROS) and the augment of glutathione. Molecular docking and dynamic simulation analyses manifested that 2 interacted with Keap1 (PDB ID: 1X2R) via forming typical hydrogen and hydrophobic bonds with residues and presented less fluctuation of RMSD and RMSF during a natural physiological condition.

Protective Effects Of Isothiocyanates Against Alzheimer's Disease

Background:

The extensive search for a novel therapeutic agent against Alzheimer's Disease (AD) in medical and pharmaceutical research still continues. Despite a lot being explored about its therapeutics, there is still much more to learn in order to achieve promising therapeutic agents against ADAlzheimer's. Phytochemicals, especially secondary metabolites, are the major focus of the investigators for AD treatment.

Objective:

To describe major therapeutics targets of AD and the role of isothiocyanates (ITCs) in modulating these targets.

Methods:

Scientific databases, including Elsevier, Science Direct, Pub med, were explored. The explored literature was mainly journal publications on pathogenesis and targets of AD, and the effect of various ITCs in the modulation of these targets.

Results:

The major targets of AD include the Nrf-2/ARE signaling pathway, MAPKs pathway, GSK-3 signaling, and Ubiquitin-Protease system. ITCs, such as Sulforaphane, Allyl isothiocyanates, Moringin, 6-(methylsulfinyl) hexyl ITC, Phenethyl isothiocyanates, and Erucin, were reported to exert a protective effect against AD via modulating one of the several above mentioned targets.

Conclusion:

This article gives a detailed description of the therapeutic targets of AD and sheds light that phytochemicals, such as ITCs, can exert a protective effect against AD by targeting those pathways. However, properly designed research and clinical trials are required to include ITCs as a mainstream agent against AD.

Sulforaphane Causes Cell Cycle Arrest and Apoptosis in Human Glioblastoma U87MG and U373MG Cell Lines under Hypoxic Conditions

Glioblastoma multiforme (GBM) is the most prevalent and aggressive primary brain tumor. The median survival rate from diagnosis ranges from 15 to 17 months because the tumor is resistant to most therapeutic strategies. GBM exhibits microvascular hyperplasia and pronounced necrosis triggered by hypoxia. Sulforaphane (SFN), an isothiocyanate derived from cruciferous vegetables, has already demonstrated the ability to inhibit cell proliferation, by provoking cell cycle arrest, and leading to apoptosis in many cell lines. In this study, we investigated the antineoplastic effects of SFN [20-80 μM for 48 h] in GBM cells under normoxic and hypoxic conditions. Cell viability assays, flow cytometry, and Western blot results revealed that SFN could induce apoptosis of GBM cells in a dose-dependent manner, under both conditions. In particular, SFN significantly induced caspase 3/7 activation and DNA fragmentation. Moreover, our results demonstrated that SFN suppressed GBM cells proliferation by arresting the cell cycle at the S-phase, also under hypoxic condition, and that these effects may be due in part to its ability to induce oxidative stress by reducing glutathione levels and to increase the phosphorylation of extracellular signal-regulated kinases (ERKs). Overall, we hypothesized that SFN treatment might serve as a potential therapeutic strategy, alone or in combination, against GBM.

Sustained Hippocampal Neural Plasticity Questions the Reproducibility of an Amyloid-β-Induced Alzheimer's Disease Model

BACKGROUND

The use of Alzheimer's disease (AD) models obtained by intracerebral infusion of amyloid-β (Aβ) has been increasingly reported in recent years. Nonetheless, these models may present important challenges.

OBJECTIVE

We have focused on canonical mechanisms of hippocampal-related neural plasticity to characterize a rat model obtained by an intracerebroventricular (icv) injection of soluble amyloid-β42 (Aβ42).

METHODS

Animal behavior was evaluated in the elevated plus maze, Y-Maze spontaneous or forced alternation, Morris water maze, and open field, starting 2 weeks post-Aβ42 infusion. Hippocampal neurogenesis was assessed 3 weeks after Aβ42 injection. Aβ deposition, tropomyosin receptor kinase B levels, and neuroinflammation were appraised at 3 and 14 days post-Aβ42 administration.

RESULTS

We found that immature neuronal dendritic morphology was abnormally enhanced, but proliferation and neuronal differentiation in the dentate gyrus was conserved one month after Aβ42 injection. Surprisingly, animal behavior did not reveal changes in cognitive performance nor in locomotor and anxious-related activity. Brain-derived neurotrophic factor related-signaling was also unchanged at 3 and 14 days post-Aβ icv injection. Likewise, astrocytic and microglial markers of neuroinflammation in the hippocampus were unaltered in these time points.

CONCLUSION

Taken together, our data emphasize a high variability and lack of behavioral reproducibility associated with these Aβ injection-based models, as well as the need for its further optimization, aiming at addressing the gap between preclinical AD models and the human disorder.

Ficus erecta Thunb. Leaves Ameliorate Cognitive Deficit and Neuronal Damage in a Mouse Model of Amyloid-β-Induced Alzheimer's Disease

Alzheimer's disease (AD) pathogenesis is linked to amyloid plaque accumulation, neuronal loss, and brain inflammation. Ficus erecta Thunb. is a food and medicinal plant used to treat inflammatory diseases. Here, we investigated the neuroprotective effects of F. erecta Thunb. against cognitive deficit and neuronal damage in a mouse model of amyloid-β (Aβ)-induced AD. First, we confirmed the inhibitory effects of ethanol extracts of F. erecta (EEFE) leaves on Aβ aggregation in vivo and in vitro. Next, behavioral tests (passive avoidance task and Morris water maze test) revealed EEFE markedly improved cognitive impairment in Aβ-injected mice. Furthermore, EEFE reduced neuronal loss and the expression of neuronal nuclei (NeuN), a neuronal marker, in brain tissues of Aβ-injected mice. EEFE significantly reversed Aβ-induced suppression of cAMP response element-binding protein (CREB) phosphorylation and brain-derived neurotrophic factor (BDNF) expression, indicating neuroprotection was mediated by the CREB/BDNF signaling. Moreover, EEFE significantly suppressed the inflammatory cytokines interleukin 1beta (IL-1β) and tumor necrosis factor alpha (TNF-α), and expression of ionized calcium-binding adaptor molecule 1 (Iba-1), a marker of microglial activation, in brain tissues of Aβ-injected mice, suggesting anti-neuroinflammatory effects. Taken together, EEFE protects against cognitive deficit and neuronal damage in AD-like mice via activation of the CREB/BDNF signaling and upregulation of the inflammatory cytokines.

Pinoresinol diglucoside attenuates neuroinflammation, apoptosis and oxidative stress in a mice model with Alzheimer's disease

For Alzheimer's disease (AD), there is still no effective treatment strategy. Pinoresinol diglucoside (PDG) is one of the major lignans isolated from Eucommia ulmoides. It is endowed with multiple pharmacological activities, including anti-inflammatory, antioxidant and anticancer activities. In this study, we investigated the potential neuroprotective functions of PDG in AD. Mice model with AD was established adopting stereotactic hippocampal injection of Aβ1-42 (410 pmol/mouse), and 3 days later, mice were administrated with 5 and 10 mg/kg PDG by intragastric administration every day for 3 weeks. Morris water maze and Y-maze tests demonstrated that PDG treatment could markedly reverse Aβ1-42-induced memory impairment in mice. It is found that PDG restrained the release of proinflammatory cytokines (tumor necrosis factor α and interleukin 1β), reactive oxygen species and malondialdehyde, and promoted the activity of the antioxidant enzyme (superoxide dismutase and catalase) by quantitative real-time-PCR, colorimetric method and ELISA assay. Western blot assay results have shown that PDG could also upregulate the ratio of Bcl-2/Bax and downregulate cytochrome c and cleaved caspase-3 expressions, thereby inhibiting neuronal apoptosis. Furthermore, PDG also significantly reduced the expression of Toll-like receptor 4 (TLR4) and the activation of nuclear factor-κB (NF-κB) p65, and promoted nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) expressions. In conclusion, PDG can attenuate neuroinflammation, neuronal apoptosis and oxidative stress through the TLR4/NF-κB and Nrf2/HO-1 pathways, and ameliorate memory dysfunction induced by Aβ1-42 in mice.

Attenuation of Nrf2/Keap1/ARE in Alzheimer's Disease by Plant Secondary Metabolites: A Mechanistic Review

Alzheimer’s disease (AD) is a progressive neuronal/cognitional dysfunction, leading to disability and death. Despite advances in revealing the pathophysiological mechanisms behind AD, no effective treatment has yet been provided. It urges the need for finding novel multi-target agents in combating the complex dysregulated mechanisms in AD. Amongst the dysregulated pathophysiological pathways in AD, oxidative stress seems to play a critical role in the pathogenesis progression of AD, with a dominant role of nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein-1 (Keap1)/antioxidant responsive elements (ARE) pathway. In the present study, a comprehensive review was conducted using the existing electronic databases, including PubMed, Medline, Web of Science, and Scopus, as well as related articles in the field. Nrf2/Keap1/ARE has shown to be the upstream orchestrate of oxidative pathways, which also ameliorates various inflammatory and apoptotic pathways. So, developing multi-target agents with higher efficacy and lower side effects could pave the road in the prevention/management of AD. The plant kingdom is now a great source of natural secondary metabolites in targeting Nrf2/Keap1/ARE. Among natural entities, phenolic compounds, alkaloids, terpene/terpenoids, carotenoids, sulfur-compounds, as well as some other miscellaneous plant-derived compounds have shown promising future accordingly. Prevailing evidence has shown that activating Nrf2/ARE and downstream antioxidant enzymes, as well as inhibiting Keap1 could play hopeful roles in overcoming AD. The current review highlights the neuroprotective effects of plant secondary metabolites through targeting Nrf2/Keap1/ARE and downstream interconnected mediators in combating AD.

Krill Oil Attenuates Cognitive Impairment by the Regulation of Oxidative Stress and Neuronal Apoptosis in an Amyloid β-Induced Alzheimer's Disease Mouse Model

In the present study, we investigated the cognitive improvement effects and its mechanisms of krill oil (KO) in Aβ_25–35-induced Alzheimer’s disease (AD) mouse model. The Aβ_25–35-injected AD mouse showed memory and cognitive impairment in the behavior tests. However, the administration of KO improved novel object recognition ability and passive avoidance ability compared with Aβ_25–35-injected control mice in behavior tests. In addition, KO-administered mice showed shorter latency to find the hidden platform in a Morris water maze test, indicating that KO improved learning and memory abilities. To evaluate the cognitive improvement mechanisms of KO, we measured the oxidative stress-related biomarkers and apoptosis-related protein expressions in the brain. The administration of KO inhibited oxidative stress-related biomarkers such as reactive oxygen species, malondialdehyde, and nitric oxide compared with AD control mice induced by Aβ_25–35. In addition, KO-administered mice showed down-regulation of Bax/Bcl-2 ratio in the brain. Therefore, this study indicated that KO-administered mice improved cognitive function against Aβ_25–35 by attenuations of neuronal oxidative stress and neuronal apoptosis. It suggests that KO might be a potential agent for prevention and treatment of AD.

Common Protective Strategies in Neurodegenerative Disease: Focusing on Risk Factors to Target the Cellular Redox System

Neurodegenerative disease is an umbrella term for different conditions which primarily affect the neurons in the human brain. In the last century, significant research has been focused on mechanisms and risk factors relevant to the multifaceted etiopathogenesis of neurodegenerative diseases. Currently, neurodegenerative diseases are incurable, and the treatments available only control the symptoms or delay the progression of the disease. This review is aimed at characterizing the complex network of molecular mechanisms underpinning acute and chronic neurodegeneration, focusing on the disturbance in redox homeostasis, as a common mechanism behind five pivotal risk factors: aging, oxidative stress, inflammation, glycation, and vascular injury. Considering the complex multifactorial nature of neurodegenerative diseases, a preventive strategy able to simultaneously target multiple risk factors and disease mechanisms at an early stage is most likely to be effective to slow/halt the progression of neurodegenerative diseases.

Deterioration of cognitive function after transient cerebral ischemia with amyloid-β infusion-possible amelioration of cognitive function by AT2 receptor activation

Background

To promote understanding of the pathogenesis of cognitive impairment or dementia, we explored the potential interaction between transient cerebral ischemia and amyloid-β (Aβ) infusion in mediating cognitive decline and examined the possible ameliorative effect of angiotensin II type 2 (AT₂) receptor activation in vascular smooth muscle cells (VSMC) on this cognitive deficit.

Methods

Adult male wild-type mice (WT) and mice with VSMC-specific AT₂ receptor overexpression (smAT₂) were subjected to intracerebroventricular (ICV) injection of Aβ1-40. Transient cerebral ischemia was induced by 15 min of bilateral common carotid artery occlusion (BCCAO) 24 h after Aβ injection.

Results

Aβ injection in WT induced a cognitive decline, whereas BCCAO did not cause a significant cognitive deficit. In contrast, WT with BCCAO following Aβ injection exhibited more marked cognitive decline compared to Aβ injection alone, in concert with increases in superoxide anion production, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, and expression of p22phox, p40phox, monocyte chemoattractant protein (MCP)-1 and interleukin (IL)-1β in the hippocampus, and upregulation of RAGE (receptor for advanced glycation end product), an Aβ transporter. BCCAO following Aβ injection further enhanced neuronal pyknosis in the hippocampus, compared with BCCAO or Aβ injection alone. In contrast, smAT₂ did not show a cognitive decline, increase in oxidative stress, inflammation, and RAGE level or neuronal pyknosis, which were induced by BCCAO with/without Aβ injection in WT.

Conclusions

Transient cerebral ischemia might worsen Aβ infusion-mediated cognitive decline and vice versa, with possible involvement of amplified oxidative stress and inflammation and impairment of the RAGE-mediated Aβ clearance system, contributing to exaggerated neuronal degeneration. AT₂ receptor activation in VSMC could play an inhibitory role in this cognitive deficit.

Nrf2 Suppresses Oxidative Stress and Inflammation in App Knock-In Alzheimer's Disease Model Mice

Nrf2 (NF-E2-related-factor 2) is a stress-responsive transcription factor that protects cells against oxidative stresses. To clarify whether Nrf2 prevents Alzheimer's disease (AD), AD model App^{NL-G-F/NL-G-F} knock-in (App^NLGF ) mice were studied in combination with genetic Nrf2 induction model Keap1^FA/FA mice. While App^NLGF mice displayed shorter latency to escape than wild-type mice in the passive-avoidance task, the impairment was improved in App^NLGF ::Keap1^FA/FA mice. Matrix-assisted laser desorption ionization-mass spectrometry imaging revealed that reduced glutathione levels were elevated by Nrf2 induction in App^NLGF ::Keap1^FA/FA mouse brains compared to App^NLGF mouse brains. Genetic Nrf2 induction in App^NLGF mice markedly suppressed the elevation of the oxidative stress marker 8-OHdG and Iba1-positive microglial cell number. We also determined the plasmalogen-phosphatidylethanolamine (PlsPE) level as an AD biomarker. PlsPE containing polyunsaturated fatty acids was decreased in the App^NLGF mouse brain, but Nrf2 induction attenuated this decline. To evaluate whether pharmacological induction of Nrf2 elicits beneficial effects for AD treatment, we tested the natural compound 6-MSITC [6-(methylsulfinyl)hexyl isothiocyanate]. Administration of 6-MSITC improved the impaired cognition of App^NLGF mice in the passive-avoidance task. These results demonstrate that the induction of Nrf2 ameliorates cognitive impairment in the AD model mouse by suppressing oxidative stress and neuroinflammation, suggesting that Nrf2 is an important therapeutic target of AD.

Antioxidative and antiapoptosis: Neuroprotective effects of dauricine in Alzheimer's disease models

AIMS

Dauricine has been found that has significant neuroprotective effect on Alzheimer's disease (AD), but the mechanism is unclear, so we further investigated the possible mechanism of dauricine on AD.

MAIN METHODS

Cell counting kit-8 (CCK8) was applied to measure the cytotoxicity of dauricine on SH-SY5Y cells that overexpress the Swedish mutant form of human β-amyloid precursor protein (APPsw) and control cells (Neo). We used the Cu²⁺ to induce oxidative damage on APPsw cells, then tested the effect of dauricine on the damage and relative factors including reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and superoxide dismutase (SOD) activity. The secretion level of amyloid beta 1-42(Aβ_1-42), protein expression of apoptosis-related factors and the components of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway were determined by western blotting. Aβ_1-42-transgenic Caenorhabditis elegans GMC101, a model of AD, was applied to evaluate the neuroprotective effect of dauricine through the behavioral experiment and relative anti-oxidative tests.

KEY FINDINGS

In vitro, dauricine decreased the secretion level of Aβ_1-42, significantly reduced the level of Cu²⁺-induced ROS, and restored MMP and SOD activity in APPsw cells. Meanwhile, dauricine could suppress the activation of caspase-3 and to upregulate the expression of Bcl-2. Dauricine also regulated the proteins levels of Nrf2, and Kelch-like ECH-associated protein 1 (Keap1) that is necessary for the activation of Nrf2 in APPsw cell. As oxidative stress induced by Aβ or paraquat (PQ), dauricine showed protective effects in the survival experiment of GMC101 worms.

SIGNIFICANCE

Those data revealed that dauricine has the pharmacological activity of anti-oxidative and anti-apoptosis, and shows the potential therapeutic value for AD.

Tanshinone IIA attenuates Aβ-induced neurotoxicity by down-regulating COX-2 expression and PGE2 synthesis via inactivation of NF-κB pathway in SH-SY5Y cells

Amyloid-β (Aβ)-induced neurotoxicity is a major pathological mechanism of Alzheimer's disease (AD). Tanshinone IIA (Tan IIA), extracted from traditional Chinese herb Radix salvia miltiorrhiza, possesses anti-oxidant and anti-inflammatory actions, as well as neuroprotective effects. The present study aims to explore the possible mechanism by which Tan IIA attenuated Aβ-induced neurotoxicity. Exposure of SH-SY5Y cells to different concentrations of Aβ led to neurotoxicity by reducing cell viability, inducing cell apoptosis and increasing neuroinflammation in a dose-dependent manner. Moreover, Aβ treatment promoted cyclooxygenase-2 (COX-2) expression and Prostaglandin E2 (PGE2) secretion, and activated nuclear transcription factor kappa (NF-κB) pathway in SH-SY5Y cells. However, pretreatment of SH-SY5Y cells with Tan IIA prior to Aβ prevented these Aβ-induced cellular events noticeably. These data suggested that Tan IIA exerted its neuroprotective action by alleviating Aβ-induced increase in COX-2 expression and PGE2 secretion via inactivation of NF-κB pathway.

PQM130, a Novel Feruloyl-Donepezil Hybrid Compound, Effectively Ameliorates the Cognitive Impairments and Pathology in a Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is the most frequent type of dementia in older people. The complex nature of AD calls for the development of multitarget agents addressing key pathogenic processes. Donepezil, an acetylcholinesterase inhibitor, is a first-line acetylcholinesterase inhibitor used for the treatment of AD. Although several studies have demonstrated the symptomatic efficacy of donepezil treatment in AD patients, the possible effects of donepezil on the AD process are not yet known. In this study, a novel feruloyl-donepezil hybrid compound (PQM130) was synthesized and evaluated as a multitarget drug candidate against the neurotoxicity induced by Aβ_1-42 oligomer (AβO) injection in mice. Interestingly, PQM130 had already shown anti-inflammatory activity in different in vivo models and neuroprotective activity in human neuronal cells. The intracerebroventricular (i.c.v.) injection of AβO in mice caused the increase of memory impairment, oxidative stress, neurodegeneration, and neuroinflammation. Instead, PQM130 (0.5-1 mg/kg) treatment after the i.c.v. AβO injection reduced oxidative damage and neuroinflammation and induced cell survival and protein synthesis through the modulation of glycogen synthase kinase 3β (GSK3β) and extracellular signal-regulated kinases (ERK1/2). Moreover, PQM130 increased brain plasticity and protected mice against the decline in spatial cognition. Even more interesting is that PQM130 modulated different pathways compared to donepezil, and it is much more effective in counteracting AβO damage. Therefore, our findings highlighted that PQM130 is a potent multi-functional agent against AD and could act as a promising neuroprotective compound for anti-AD drug development.