Beyond symptomatic effects: potential of donepezil as a neuroprotective agent and disease modifier in Alzheimer's disease

Preparation and application of multiple particle binding-liposomes for electrochemiluminescent signal amplification in bioassays

In this study, multiple particle binding-liposomes (MPB-Lips), encapsulating the luminophore tris(2',2-bipyridyl)ruthenium (II) complex ([Ru(bpy)3]2+), were developed as an electrochemiluminescence (ECL) signal amplifier and were applied to detect the model analyte streptavidin (SA) using the indirect competitive ECL method. The MPB-Lips were prepared by mixing various ratios of two different liposomes-one containing a phospholipid with a primary amine group and a biotinyl group (BIO/NH2-Lip) and one containing a phospholipid with an N-hydroxysuccinimide group (NHS-Lip) to allow binding between particles via amide bonds. Quartz crystal microbalance analysis using SA-modified gold-coated quartz crystals showed that the frequency shift values of MPB-Lips gradually decreased in the order BIO/NH2-Lip:NHS-Lip = 1:0 < 1:1 < 1:3 < 1:5. This indicated that MPB-Lips were successfully formed. The indirect competitive ECL method using SA-modified gold electrodes showed that the 1:5-Lip system had greater sensitivity than the 1:0-Lip system-the limit of detection and quantification values for the systems were 1.84 and 6.30 μg mL-1 for 1:0-Lip, and 1.20 and 1.74 μg mL-1 for 1:5-Lip. Finally, the recovery of SA spiked in fetal bovine serum samples using the 1:5-Lip system showed good accuracy and precision with a recovery rate of 83-106% and relative standard deviation of 4-14%. Our study demonstrated that the MPB-Lips system was an effective and useful ECL amplifier and the ECL method using MPB-Lips could be applied to detect an analyte in a real sample.

Intranasal Carrier-Free Nanomodulator Addresses Both Symptomatology and Etiology of Alzheimer's Disease by Restoring Neuron Plasticity and Reprogramming Lesion Microenvironment

The unsatisfactory treatment outcome of Alzheimer's disease (AD) can be attributed to two primary factors, the intricate pathogenic mechanisms leading to restricted treatment effectiveness against single targets and the hindered drug accumulation in brain due to blood-brain barrier obstruction. Therefore, we developed a carrier-free nanomodulator (NanoDS) through the self-assembly of donepezil and simvastatin for direct nose-to-brain delivery. This approach facilitated a rapid and efficient traversal through the nasal epithelial barrier, enabling subsequent drug release and achieving multiple therapeutic effects. Among them, donepezil effectively ameliorated the symptoms of AD and restored synaptic plasticity. Simvastatin exerted a neurotrophic effect and facilitated the clearance of amyloid-β aggregation. At the same time, NanoDS demonstrated effective anti-inflammatory and antioxidative stress effects. This therapy for AD is approached from both symptomatic and etiological perspectives. In the treatment of FAD4T transgenic mice, it highly improved spatial memory impairment and cognitive deficits while restoring the homeostasis of brain microenvironment. Collectively, our study presented a paradigm for both achieving efficient brain delivery and offering pleiotropic therapies for AD.

Understanding the Antidepressant Mechanisms of Acupuncture: Targeting Hippocampal Neuroinflammation, Oxidative Stress, Neuroplasticity, and Apoptosis in CUMS Rats

Depression is recognized globally as one of the most intractable diseases, and its complexity and diversity make treatment extremely challenging. Acupuncture has demonstrated beneficial effects in various psychiatric disorders. However, the underlying mechanisms of acupuncture's antidepressant action, particularly in depression, remain elusive. Therefore, this study aimed to investigate the effects of acupuncture on chronic unpredictability stress (CUMS)-induced depressive symptoms in rats and to further elucidate its underlying molecular mechanisms. All rats were exposed to CUMS of two stressors every day for 28 days, except for the control group. One hour before CUMS, rats were given a treatment with acupuncture, electroacupuncture, sham-acupuncture, or fluoxetine (2.1 mg/kg). Behavioral tests and biological detection methods were conducted in sequence to evaluate depression-like phenotype in rats. The findings of this study demonstrate that acupuncture therapy effectively ameliorated depression-like behavior induced by CUMS in rats. Additionally, acupuncture exerted a restorative effect on the alterations induced by CUMS in the levels of malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), brain-derived neurotrophic factor (BDNF), cyclic AMP response element-binding protein (CREB), postsynaptic density95 (PSD95), gamma-aminobutyric acid (GABA), and acetylcholine (ACh). Additionally, our findings indicate that acupuncture also modulates the ERK and Caspase-3 apoptotic pathways in the hippocampus of CUMS rats. This study suggests that acupuncture may play a potential preventive role by regulating hippocampal neuroinflammatory response, levels of oxidative stress, apoptotic processes, and enhancing synaptic plasticity.

Therapeutic Effects Of Combined and Chronic Treatment of Tat-GluA23y and D-Serine on Cognitive Dysfunction in Postmenopausal Rats

BACKGROUND

The incidence of Alzheimer's disease (AD) in female gender compared with male has been addressed as a health concern, particularly in menopausal age. We here hypothesized that co-administration of NMDARs agonist (D-serine) and AMPARs endocytosis inhibitor (Tat-GluA23y) might be a potential target for alleviating memory impairment in sporadic Alzheimer model of rats.

METHODS

Forty-eight female Wistar rats weighing 200-220 randomly divided into six groups. One month later, ovariectomized rats underwent stereotaxic surgery and were cannulated into the brain lateral ventricles. Streptozotocin was injected (3 mg/kg), then animals received the related treatments until the day 51, which experienced acquisition of spatial memory in Morris Water Maze test. Finally, the level of phosphorylated cAMP response element binding protein (CREB) in the hippocampus was measured by Western blotting.

RESULTS

Co-administration of D-serine and GluA23y significantly enhanced the acquisition and retrieval of impaired spatial memory in ovariectomized rats with AD (p < .001). Compared to Glu-A 23, D-serine caused more improvement in the mentioned parameters above, however, these values for both groups were still significantly different from the control group (P < .05).

CONCLUSION

Simultaneous treatment with D-serine and GluA23y synergistically improved STZ induced spatial memory impairment in OVX rat, probably partly via increase in phosphorylated CREB protein.

Research evidence on the management of the cognitive impairment component of the post-COVID condition: a qualitative systematic review

BACKGROUND

Cognitive impairment (CI) is one of the most prevalent and burdensome consequences of COVID-19 infection, which can persist up to months or even years after remission of the infection. Current guidelines on post-COVID CI are based on available knowledge on treatments used for improving CI in other conditions. The current review aims to provide an updated overview of the existing evidence on the efficacy of treatments for post-COVID CI.

METHODS

A systematic literature search was conducted for studies published up to December 2023 using three databases (PubMed-Scopus-ProQuest). Controlled and noncontrolled trials, cohort studies, case series, and reports testing interventions on subjects with CI following COVID-19 infection were included.

RESULTS

After screening 7790 articles, 29 studies were included. Multidisciplinary approaches, particularly those combining cognitive remediation interventions, physical exercise, and dietary and sleep support, may improve CI and address the different needs of individuals with post-COVID-19 condition. Cognitive remediation interventions can provide a safe, cost-effective option and may be tailored to deficits in specific cognitive domains. Noninvasive brain stimulation techniques and hyperbaric oxygen therapy showed mixed and preliminary results. Evidence for other interventions, including pharmacological ones, remains sparse. Challenges in interpreting existing evidence include heterogeneity in study designs, assessment tools, and recruitment criteria; lack of long-term follow-up; and under-characterization of samples in relation to confounding factors.

CONCLUSIONS

Further research, grounded on shared definitions of the post-COVID condition and on the accurate assessment of COVID-related CI, in well-defined study samples and with longer follow-ups, is crucial to address this significant unmet need.

Multi-target drugs for Alzheimer's disease

Alzheimer's disease (AD), a leading cause of dementia, increasingly challenges our healthcare systems and society. Traditional therapies aimed at single targets have fallen short owing to the complex, multifactorial nature of AD that necessitates simultaneous targeting of various disease mechanisms for clinical success. Therefore, targeting multiple pathologies at the same time could provide a synergistic therapeutic effect. The identification of new disease targets beyond the classical hallmarks of AD offers a fertile ground for the design of new multi-target drugs (MTDs), and building on existing compounds have the potential to yield in successful disease modifying therapies. This review discusses the evolving landscape of MTDs, focusing on their potential as AD therapeutics. Analysis of past and current trials of compounds with multi-target activity underscores the capacity of MTDs to offer synergistic therapeutic effects, and the flourishing genetic understanding of AD will inform and inspire the development of MTD-based AD therapies.

Donepezil-Loaded Nanocarriers for the Treatment of Alzheimer's Disease: Superior Efficacy of Extracellular Vesicles Over Polymeric Nanoparticles

Introduction

Drug delivery across the blood-brain barrier (BBB) is challenging and therefore severely restricts neurodegenerative diseases therapy such as Alzheimer's disease (AD). Donepezil (DNZ) is an acetylcholinesterase (AChE) inhibitor largely prescribed to AD patients, but its use is limited due to peripheral adverse events. Nanodelivery strategies with the polymer Poly (lactic acid)-poly(ethylene glycol)-based nanoparticles (NPs-PLA-PEG) and the extracellular vesicles (EVs) were developed with the aim to improve the ability of DNZ to cross the BBB, its brain targeting and efficacy.

Methods

EVs were isolated from human plasma and PLA-PEG NPs were synthesized by nanoprecipitation. The toxicity, brain targeting capacity and cholinergic activities of the formulations were evaluated both in vitro and in vivo.

Results

EVs and NPs-PLA-PEG were designed to be similar in size and charge, efficiently encapsulated DNZ and allowed sustained drug release. In vitro study showed that both formulations EVs-DNZ and NPs-PLA-PEG-DNZ were highly internalized by the endothelial cells bEnd.3. These cells cultured on the Transwell® model were used to analyze the transcytosis of both formulations after validation of the presence of tight junctions, the transendothelial electrical resistance (TEER) values and the permeability of the Dextran-FITC. In vivo study showed that both formulations were not toxic to zebrafish larvae (Danio rerio). However, hyperactivity was evidenced in the NPs-PLA-PEG-DNZ and free DNZ groups but not the EVs-DNZ formulations. Biodistribution analysis in zebrafish larvae showed that EVs were present in the brain parenchyma, while NPs-PLA-PEG remained mainly in the bloodstream.

Conclusion

The EVs-DNZ formulation was more efficient to inhibit the AChE enzyme activity in the zebrafish larvae head. Thus, the bioinspired delivery system (EVs) is a promising alternative strategy for brain-targeted delivery by substantially improving the activity of DNZ for the treatment of AD.

Biochemical characterization of chamomile essential oil: Antioxidant, antibacterial, anticancer and neuroprotective activity and potential treatment for Alzheimer's disease

Alzheimer's disease (AD) causes dementia among older adults, increasing the global burden of dementia. Therefore, this study investigates the potential neuroprotective, antioxidant, and anticancer effects of chamomile essential oil (CCO) in Alzheimer's disease. CCO's main volatile compounds (VOCs) were α-bisabolol, camazulene, and bisabolol oxide A, representing 81 % of all VOCs. CCO scavenged 93 % of DPPH free radicals and inhibited the pathogenic bacteria, i.e., Staphylococcus aureus and Salmonella typhi, besides reducing 89 % of brain cancer cell lines (U87). Eighty albino rats were randomized into four groups: standard control, Alzheimer's disease group caused by AlCl3, and treated groups. The results indicated that the mean value of tumor necrosis factor α (TNF-α), amyloid precursor protein (APP), amyloid beta (Aβ), caspase-3, & B-cell lymphoma 2 (Bcl-2) was significantly elevated due to the harmful effect of AlCl3; however, CCO downregulated these values, and this effect was attributed to the considerable volatile compounds and phenolic compounds content. Additionally, CCO rats showed a significant increment in noradrenergic (NE), dopaminergic (DO), and serotoninergic systems with relative increases of 50, 50, and 14 % compared to diseased rats. The brain histology of CCO-treated rats showed a significant reduction in neuronal degeneration and improved brain changes, and its histology was close to that of the control brain. The results indicated that CCO offers a new strategy that could be used as an antioxidant and neuroprotective agent for AD due to its considerable contents of antioxidants and anti-inflammatory compounds.

Electroacupuncture stimulation improves cognitive ability and regulates metabolic disorders in Alzheimer's disease model mice: new insights from brown adipose tissue thermogenesis

Background

Metabolic defects play a crucial role in Alzheimer's disease (AD) development. Brown adipose tissue (BAT) has been identified as a novel potential therapeutic target for AD due to its unique role in energy metabolism. Electroacupuncture (EA) shows promise in improving cognitive ability and brain glucose metabolism in AD, but its effects on peripheral and central metabolism are unclear.

Methods

In this study, SAMP8 mice (AD model) received EA stimulation at specific acupoints. Cognitive abilities were evaluated using the Morris water maze test, while neuronal morphology and tau pathology were assessed through Nissl staining and immunofluorescence staining, respectively. Metabolic variations and BAT thermogenesis were measured using ELISA, HE staining, Western blotting, and infrared thermal imaging.

Results

Compared to SAMR1 mice, SAMP8 mice showed impaired cognitive ability, neuronal damage, disrupted thermoregulation, and metabolic disorders with low BAT activity. Both the EA and DD groups improved cognitive ability and decreased tau phosphorylation (p<0.01 or p<0.05). However, only the EA group had a significant effect on metabolic disorders and BAT thermogenesis (p<0.01 or p<0.05), while the DD group did not.

Conclusion

These findings indicate that EA not only improves the cognitive ability of SAMP8 mice, but also effectively regulates peripheral and central metabolic disorders, with this effect being significantly related to the activation of BAT thermogenesis.

The effect of donepezil hydrochloride on post-COVID memory impairment: A randomized controlled trial

BACKGROUND

Post-Coronavirus Disease (COVID-19) condition, known as "post-COVID syndrome," is associated with a range of complications persisting even after recovery. Among these complications, cognitive dysfunction, including memory impairment, has been relatively common observed, impacting executive function and quality of life. To date, no approved treatment exists for this specific complication. Therefore, the present clinical trial aimed to investigate the impact of Donepezil Hydrochloride on post-COVID memory impairment.

METHODS

A randomized, controlled trial (Approval ID: IRCT20210816052203N1) was conducted, enrolling 25 patients with post-COVID memory impairment. Participants with a history of hospitalization were randomly assigned to either the drug group (n = 10) or the control group (n = 15). Memory indices were assessed at baseline, one month, and three months later using the Wechsler Memory Scale-Revised test. SPSS software and appropriate statistical tests were employed for data analysis.

RESULTS

The statistical analysis revealed no significant difference in WMS-R subtest and index scores between the drug and control groups at the 4-week and 12-week follow-up periods. However, within the drug group, there was a notable increase in the visual reproduction I and verbal paired associates II subtests during the specified time intervals.

CONCLUSION

While donepezil 5 mg did not exhibit a significant overall increase in memory scales compared to the control group over time, our findings suggest that this medication may exert a positive effect on specific memory subtests. Further research and exploration are warranted to better understand the potential benefits of donepezil in managing post-COVID-related memory impairment.

TRIAL REGISTRATION

The study was approved by the Research Ethics Committee of Aja University of Medical Sciences (Approval ID: IR.AJAUMS.REC.1400.125) and registered in the Iranian Registry of Clinical Trials (IRCT) (Approval ID: IRCT20210816052203N1).

Natural compounds as lactate dehydrogenase inhibitors: potential therapeutics for lactate dehydrogenase inhibitors-related diseases

Lactate dehydrogenase (LDH) is a crucial enzyme involved in energy metabolism and present in various cells throughout the body. Its diverse physiological functions encompass glycolysis, and its abnormal activity is associated with numerous diseases. Targeting LDH has emerged as a vital approach in drug discovery, leading to the identification of LDH inhibitors among natural compounds, such as polyphenols, alkaloids, and terpenoids. These compounds demonstrate therapeutic potential against LDH-related diseases, including anti-cancer effects. However, challenges concerning limited bioavailability, poor solubility, and potential toxicity must be addressed. Combining natural compounds with LDH inhibitors has led to promising outcomes in preclinical studies. This review highlights the promise of natural compounds as LDH inhibitors for treating cancer, cardiovascular, and neurodegenerative diseases.

Simvastatin attenuates aluminium chloride-induced neurobehavioral impairments through activation of TGF-β1/ SMAD2 and GSK3β/β-catenin signalling pathways

Alzheimer's disease (AD) is a neurodegenerative disease characterised by the presence of β-amyloid plaques and acetylcholine depletion leading to neurobehavioral defects. AD was contributed also with downregulation of TGF-β1/SMAD2 and GSK3β/β-catenin pathways. Simvastatin (SMV) improved memory function experimentally and clinically. Hence, this study aimed to investigate the mechanistic role of SMV against aluminium chloride (AlCl3) induced neurobehavioral impairments. AD was induced by AlCl3 (50 mg/kg) for 6 weeks. Mice received Simvastatin (10 or 20 mg/kg) or Donepezil (3 mg/kg) for 6 weeks after that the histopathological, immunohistochemical and biochemical test were examined. Treatment with SMV improved the memory deterioration induced by AlCl3 with significant recovery of the histopathological changes. This was concomitant with the decrease of AChE and Aβ (1-42). SMV provides its neuroprotective effect through upregulating the protein expression of β-catenin, TGF-β1 and downregulating the expression of GSK3β, TLR4 and p-SMAD2.

Combined Donepezil with Astaxanthin via Nanostructured Lipid Carriers Effective Delivery to Brain for Alzheimer's Disease in Rat Model

Introduction

Donepezil (DPL), a specific acetylcholinesterase inhibitor, is used as a first-line treatment to improve cognitive deficits in Alzheimer's disease (AD) and it might have a disease modifying effect. Astaxanthin (AST) is a natural potent antioxidant with neuroprotective, anti-amyloidogenic, anti-apoptotic, and anti-inflammatory effects. This study aimed to prepare nanostructured lipid carriers (NLCs) co-loaded with donepezil and astaxanthin (DPL/AST-NLCs) and evaluate their in vivo efficacy in an AD-like rat model 30 days after daily intranasal administration.

Methods

DPL/AST-NLCs were prepared using a hot high-shear homogenization technique, in vitro examined for their physicochemical parameters and in vivo evaluated. AD induction in rats was performed by aluminum chloride. The cortex and hippocampus were isolated from the brain of rats for biochemical testing and histopathological examination.

Results

DPL/AST-NLCs showed z-average diameter 149.9 ± 3.21 nm, polydispersity index 0.224 ± 0.017, zeta potential -33.7 ± 4.71 mV, entrapment efficiency 81.25 ±1.98% (donepezil) and 93.85 ±1.75% (astaxanthin), in vitro sustained release of both donepezil and astaxanthin for 24 h, spherical morphology by transmission electron microscopy, and they were stable at 4-8 ± 2°C for six months. Differential scanning calorimetry revealed that donepezil and astaxanthin were molecularly dispersed in the NLC matrix in an amorphous state. The DPL/AST-NLC-treated rats showed significantly lower levels of nuclear factor-kappa B, malondialdehyde, β-site amyloid precursor protein cleaving enzyme-1, caspase-3, amyloid beta (Aβ1‑42), and acetylcholinesterase, and significantly higher levels of glutathione and acetylcholine in the cortex and hippocampus than the AD-like untreated rats and that treated with donepezil-NLCs. DPL/AST-NLCs showed significantly higher anti-amyloidogenic, antioxidant, anti-acetylcholinesterase, anti-inflammatory, and anti-apoptotic effects, resulting in significant improvement in the cortical and hippocampal histopathology.

Conclusion

Nose-to-brain delivery of DPL/AST-NLCs is a promising strategy for the management of AD.

Concurrent high-intensity interval training and probiotic supplementation improve associative memory via increase in insulin sensitivity in ovariectomized rats

OBJECTIVES

Metabolic syndrome (MetS) is a serious concern among postmenopausal women which predisposes them to cardiovascular and cognitive disorders. Healthful diet and exercise training have been essential strategies to prevent the progress of MetS. The aim of this study was to evaluate the effect of supplementation with a native potential probiotic and high-intensity interval training (HIIT) for 8 weeks on retention of associative memory in rats with ovariectomy- induced metabolic syndrome.

METHOD

Thirty-two female ovariectomized Wistar rats were divided into four groups (n = 8/group): Control (OVX + Veh), exercise (OVX + Exe), probiotic (OVX + Pro), exercise with probiotic (OVX + Exe + Pro). One sham surgery group was included as a control group. Animals received 8 weeks interventions, and then were tested in a step through passive avoidance learning and memory paradigm, to assess long term memory. Then serum levels of adiponectin, insulin and glucose were measured by ELISA and colorimetry respectively. Data were analyzed by Kruskal-Wallis, Mann-Whitney and also One-way analysis of variance (ANOVA).

RESULTS

Eight weeks of HIIT and probiotic supplementation caused an increase in step through latency and shortening of total time spent in the dark compartment in OVX + Exe + Pro group compared with OVX + Veh group. Also significant increase in serum adiponectin levels, in parallel with a reduction in glucose, insulin and HOMA-IR were achieved by the group of OVX + Exe + Pro.

CONCLUSION

The present study indicates that HIIT combined with probiotics supplementation for 8 weeks effectively improves associative memory in MetS model of rats partly via improving insulin sensitivity and adiponectin level.

Edaravone Improves Streptozotocin-Induced Memory Impairment via Alleviation of Behavioral Dysfunction, Oxidative Stress, Inflammation, and Histopathological Parameters

Alzheimer's disease (AD), as the main cause of dementia, has a progressive and neurodegenerative pattern with number of cases increasing over the next decades. Therefore, discovering an effective treatment with the ability to invert memory impairment and pathophysiological events of AD seems to be required. The present study performed to investigate the probable effects of Edaravone (EDV) in AD-like disorder induced by intracerebroventricular streptozotocin (ICV-STZ) administration in mice. This study also compares the two different methods of ICV-STZ in the memory impairment induction. NMRI male mice were administrated with 3 mg/kg of STZ for two times during 48 hours span, and after 24 hours, animals were treated with EDV (5 and 10 mg/kg), Donepezil, and Memantine for 14 days. After behavioral tests regarding memory and cognitive function, animals were sacrificed, and the hippocampi were utilized for further analyses. Our results demonstrated that administration of STZ induced memory impairment in the Morris water maze (MWM) test and decreased the discriminative factor in novel object recognition (NOR). The biochemical output shows a significant decrease in ferric reducing antioxidant power (FRAP) and glutathione (GSH) levels followed by increase in malondialdehyde (MDA) and protein carbonylation (PCO) levels. The output showed no difference between the patterns of AD-like disorder induction. Following our treatment groups, administration of EDV (5 and 10 mg/kg), Donepezil, and Memantine significantly improved memory performance and discriminatory behavior. Aforementioned treatments managed to improve FRAP and GSH content of hippocampus, while significantly attenuating MDA, PCO, and nitric oxide overproduction. In addition, no significant difference has been observed between the effect of 5 and 10 mg/kg EDV application. It was supposed that EDV managed to ameliorate memory dysfunction, discriminatory behavior, oxidative stress, and cellular antioxidant power in a dose-independent pattern in mice.

Basic information about memantine and its treatment of Alzheimer's disease and other clinical applications

Memantine is a noncompetitive moderate-affinity strong voltage-dependent N-methyl-D-aspartate receptor antagonist. It has been used to treat Alzheimer's disease (AD) since 1989. In 2018, it became the second most commonly used drug for the treatment of dementia in the world. AD is nonreversible, and memantine can only relieve the symptoms of AD but not cure it. Over the past half-century, memantine's research and clinical application have been extensively developed. In this review, the basic composition of memantine, the mechanism and limitations of memantine in the treatment of AD, memantine combination therapy, comparison of memantine with other drugs for AD, and clinical studies of memantine in other diseases are reviewed to provide a valuable reference for further research and application of memantine for the treatment of AD.

Vertigoheel promotes rodent cognitive performance in multiple memory tests

Introduction

Cognitive impairment associated with old age or various brain disorders may be very disabling for affected individuals, placing their carers and public health services under considerable stress. The standard-of-care drugs produce only transient improvement of cognitive impairment in older people, so the search for novel, safe and effective therapeutics that would help to reverse or delay cognitive impairment is warranted. Repurposing pharmacological therapies with well-established safety record for additional indications is a promising recent trend in drug development. Vertigoheel (VH-04), a multicomponent drug made of Ambra grisea, Anamirta cocculus L., Conium maculatum, and Petroleum rectificatum, has been successfully used for several decades in the treatment of vertigo. Here, we investigated effects of VH-04 on cognitive performance in standard behavioral tests assessing different types of memory and explored cellular and molecular underpinnings of VH-04's biological activity.

Methods

In the majority of behavioral experiments, namely in the spontaneous and rewarded alternation tests, passive avoidance test, contextual/cued fear conditioning, and social transmission of food preference, we examined the ability of single and repeated intraperitoneal administrations of VH-04 to improve cognitive parameters of mice and rats disrupted by the application of the muscarinic antagonist scopolamine. In addition, we also assessed how VH-04 affected novel object recognition and influenced performance of aged animals in Morris water maze. Furthermore, we also studied the effects of VH-04 on primary hippocampal neurons in vitro and mRNA expression of synaptophysin in the hippocampus.

Results

Administration of VH-04 positively influenced visual recognition memory in the novel object recognition test and alleviated the impairments in spatial working memory and olfactory memory caused by the muscarinic antagonist scopolamine in the spontaneous alternation and social transmission of food preference tests. In addition, VH-04 improved retention of the spatial orientation memory of old rats in the Morris water maze. In contrast, VH-04 did not have significant effects on scopolamine-induced impairments in tests of fear-aggravated memory or rewarded alternation. Experiments in vitro showed that VH-04 stimulated neurite growth and possibly reversed the age-dependent decrease in hippocampal synaptophysin mRNA expression, which implies that VH-04 may preserve synaptic integrity in the aging brain.

Discussion

Our findings allow a cautious conclusion that in addition to its ability to alleviate manifestations of vertigo, VH-04 may be also used as a cognitive enhancer.

Insulin‐like growth factor‐2 is a promising candidate for the treatment and prevention of Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia. Current AD treatments slow the rate of cognitive decline, but do not restore lost function. One reason for the low efficacy of current treatments is that they fail to target neurotrophic processes, which are thought to be essential for functional recovery. Bolstering neurotrophic processes may also be a viable strategy for preventative treatment, since structural losses are thought to underlie cognitive decline in AD. The challenge of identifying presymptomatic patients who might benefit from preventative treatment means that any such treatment must meet a high standard of safety and tolerability. The neurotrophic peptide insulin-like growth factor-2 (IGF2) is a promising candidate for both treating and preventing AD-induced cognitive decline. Brain IGF2 expression declines in AD patients. In rodent models of AD, exogenous IGF2 modulates multiple aspects of AD pathology, resulting in (1) improved cognitive function; (2) stimulation of neurogenesis and synaptogenesis; and, (3) neuroprotection against cholinergic dysfunction and beta amyloid-induced neurotoxicity. Preclinical evidence suggests that IGF2 is likely to be safe and tolerable at therapeutic doses. In the preventative treatment context, the intranasal route of administration is likely to be the preferred method for achieving the therapeutic effect without risking adverse side effects. For patients already experiencing AD dementia, routes of administration that deliver IGF2 directly access the CNS may be necessary. Finally, we discuss several strategies for improving the translational validity of animal models used to study the therapeutic potential of IGF2.

Neuroprotective effects of combined therapy with memantine, donepezil, and vitamin D in ovariectomized female mice subjected to dementia model

Women older than 60 have a higher risk of dementia, aging-related cognitive decline, and Alzheimer's Disease (AD) than the rest of the population. The main reason is hormonal senescence after menopause, a period characterized by a decline in estrogen levels. Since the effectiveness of drugs currently approved for the treatment of AD is limited, it is necessary to seek the development of new therapeutic strategies. Vitamin D deficiency is prevalent in AD patients and individuals with dementia in general. The supplementation of this vitamin in dementia patients might be an interesting approach for increasing the effectiveness of pre-existing medications for dementia treatment. Thus, the present study aims to investigate the effect of vitamin D treatment associated with memantine and donepezil in female mice submitted to ovariectomy (OVX) for five months and subjected to a dementia animal model induced by intracerebroventricular injection of aggregated amyloid βeta (Aβ_1-42). For this purpose, Balb/c mice were divided into five experimental groups, which received 17 days of combined therapy with vitamin D, donepezil, and memantine. Then, animals were subjected to behavioral tests. OVX groups exhibited reduced levels of estradiol (E2) in serum, which was not altered by the combined therapy. Higher levels of vitamin D3 were found in the OVX animals submitted to the triple-association treatment. Mice exposed to both OVX and the dementia animal model presented impairment in short and long-term spatial and habituation memories. Also, female mice exposed to Aβ and OVX exhibited a reduction in brain-derived neurotrophic factor (BDNF) and interleukin-4 (IL-4) levels, and an increase in tumor necrose factor-α (TNFα) levels in the hippocampus. Besides, increased levels of IL-1β in the hippocampus and cerebral cortex were observed, as well as a significant increase in immunoreactivity for glial fibrillary acidic protein (GFAP), an astrocytes marker, in the hippocampus. Notably, triple-association treatment reversed the effects of the exposition of mice to Aβ and OVX in the long-term spatial and habituation memories impairment, as well as reversed changes in TNFα, IL-1β, IL-4, and GFAP immunoreactivity levels in the hippocampus of treated animals. Our results indicate that the therapeutic association of vitamin D, memantine, and donepezil has beneficial effects on memory performance and attenuated the neuroinflammatory response in female mice subjected to OVX associated with a dementia animal model.

Determinants of approved acetylcholinesterase inhibitor response outcomes in Alzheimer's disease: relevance for precision medicine in neurodegenerative diseases

Acetylcholinesterase inhibitors (ChEI) are the global standard of care for the symptomatic treatment of Alzheimer's disease (AD) and show significant positive effects in neurodegenerative diseases with cognitive and behavioral symptoms. Although experimental and large-scale clinical evidence indicates the potential long-term efficacy of ChEI, primary outcomes are generally heterogeneous across outpatient clinics and regional healthcare systems. Sub-optimal dosing or slow tapering, heterogeneous guidelines about the timing for therapy initiation (prodromal versus dementia stages), healthcare providers' ambivalence to treatment, lack of disease awareness, delayed medical consultation, prescription of ChEI in non-AD cognitive disorders, contribute to the negative outcomes. We present an evidence-based overview of determinants, spanning genetic, molecular, and large-scale networks, involved in the response to ChEI in patients with AD and other neurodegenerative diseases. A comprehensive understanding of cerebral and retinal cholinergic system dysfunctions along with ChEI response predictors in AD is crucial since disease-modifying therapies will frequently be prescribed in combination with ChEI. Therapeutic algorithms tailored to genetic, biological, clinical (endo)phenotypes, and disease stages will help leverage inter-drug synergy and attain optimal combined response outcomes, in line with the precision medicine model.

Donepezil Beyond Alzheimer's Disease? A Narrative Review of Therapeutic Potentials of Donepezil in Different Diseases

Donepezil hydrochloride is an acetylcholine esterase inhibitor studied and approved to treat Alzheimer's disease (AD). However, this drug can have positive therapeutic potential in treating different conditions, including various neurodegenerative disorders such as other types of dementia, multiple sclerosis, Parkinson's disease, psychiatric and mood disorders, and even infectious diseases. Hence, this study reviewed the therapeutic potential of this drug in treating Alzheimer's and other diseases by reviewing the articles from databases including Web of Science, Scopus, PubMed, Cochrane, and Science Direct. It was shown that donepezil could affect the pathophysiology of these diseases via mechanisms such as increasing the concentration of acetylcholine, modulating local and systemic inflammatory processes, affecting acetylcholine receptors like nicotinic and muscarinic receptors, and activating various cellular signaling via receptors like sigma-1 receptors. Despite many therapeutic potentials, this drug has not yet been approved for treating non-Alzheimer's diseases, and more comprehensive studies are needed.

Efficacy of donepezil for the treatment of oxaliplatin-induced peripheral neuropathy: DONEPEZOX, a protocol of a proof of concept, randomised, triple-blinded and multicentre trial

BACKGROUND

The use of oxaliplatin in digestive tract cancers could induce severe peripheral neuropathy (OIPN) decreasing the quality of life of patients and survivors. There is currently, no univocal treatment for these peripheral neuropathies. Donepezil, a reversible inhibitor of cholinesterase, used to treat Alzheimer's disease and dementia, is reported to have a good safety profile in humans, and preclinical data have provided initial evidence of its effectiveness in diminishing neuropathic symptoms and related comorbidities in OIPN animal models.

METHODS

The DONEPEZOX trial will be a proof-of-concept, randomised, triple-blinded, and multicentre study. It will be the first clinical trial evaluating the efficacy and safety of donepezil for the management of OIPN. Adult cancer survivors with OIPN that report sensory neuropathy according to QLQ-CIPN20 sensory score (equivalence of a grade ≥ 2), at least 6 months after the end of an oxaliplatin-based chemotherapy will be included. Eighty patients will be randomly assigned to receive either donepezil or placebo over 16 weeks of treatment. The primary endpoint will be the rate of responders (neuropathic grade decreases according to the QLQ-CIPN20 sensory score) in the donepezil arm. The severity of OIPN will be assessed by the QLQ-CIPN20 sensory scale before and after 16 weeks of treatment. The comparison versus the placebo arm will be a secondary objective. The other secondary endpoints will be tolerance to donepezil, the severity and features of OIPN in each arm before and after treatment, related-comorbidities and quality of life. Fleming's one-stage design will be used for sample size estimation. This design yields a type I error rate of 0.0417 and power of 91% for a responder rate of at least 30% in donepezil arm. A total of 80 randomized patients is planned.

DISCUSSION

This study will allow, in the case of positive results, to initiate a phase 3 randomized and placebo-controlled (primary endpoint) clinical study to assess the therapeutic interest of donepezil to treat OIPN.

TRIAL REGISTRATION

NCT05254639 , clincialtrials.gov, Registered 24 February 2022.

Mechanisms of Mitochondrial Malfunction in Alzheimer’s Disease: New Therapeutic Hope

Mitochondria play a critical role in neuron viability or death as it regulates energy metabolism and cell death pathways. They are essential for cellular energy metabolism, reactive oxygen species production, apoptosis, Ca⁺⁺ homeostasis, aging, and regeneration. Mitophagy and mitochondrial dynamics are thus essential processes in the quality control of mitochondria. Improvements in several fundamental features of mitochondrial biology in susceptible neurons of AD brains and the putative underlying mechanisms of such changes have made significant progress. AD's etiology has been reported by mitochondrial malfunction and oxidative damage. According to several recent articles, a continual fusion and fission balance of mitochondria is vital in their normal function maintenance. As a result, the shape and function of mitochondria are inextricably linked. This study examines evidence suggesting that mitochondrial dysfunction plays a significant early impact on AD pathology. Furthermore, the dynamics and roles of mitochondria are discussed with the link between mitochondrial malfunction and autophagy in AD has also been explored. In addition, recent research on mitochondrial dynamics and mitophagy in AD is also discussed in this review. It also goes into how these flaws affect mitochondrial quality control. Furthermore, advanced therapy techniques and lifestyle adjustments that lead to improved management of the dynamics have been demonstrated, hence improving the conditions that contribute to mitochondrial dysfunction in AD.

Challenges and approaches of drugs such as Memantine, Donepezil, Rivastigmine and Aducanumab in the treatment, control and management of Alzheimer's disease

Alzheimer's disease (AD) is a kinds of neuropsychiatric illnesses that affect the central nervous system. In this disease, the accumulation of amyloid-beta increases, and phosphorylated tau (P-tau) protein, one of the ways to treat this disease is to reduce the accumulation of amyloid-beta. Various studies have demonstrated that pharmacological approaches have considerable effects in the treatment of AD, despite the side effects and challenges. Cholinesterase inhibitors and the NMDA receptor antagonist memantine are presently authorized therapies for AD. Memantine and Donepezil are the most common drugs for the prevention and therapy of AD with mechanisms such as lessened β-amyloid plaque, effect on N-Methyl-D-aspartate (NMDA) receptors. Diminution glutamate and elevated acetylcholine are some of the influences of medications administrated to treat AD, and drugs can also play a role in slowing the progression of cognitive and memory impairment. A new pharmacological approach and strategy is required to control the future of AD. This review appraises the effects of memantine, donepezil, rivastigmine, and aducanumab in clinical trials, in vitro and animal model studies that have explored how these drugs versus AD development and also discuss possible mechanisms of influence on the brain. Research in clinical trials has substantial findings that support the role of these medications in AD treatment and ameliorate the safety and efficacy of AD therapy, although more clinical trials are required to prove their effectiveness.

Adult-Onset Leukoencephalopathy With Axonal Spheroids and Pigmented Glia: Review of Clinical Manifestations as Foundations for Therapeutic Development

A comprehensive review of published literature was conducted to elucidate the genetics, neuropathology, imaging findings, prevalence, clinical course, diagnosis/clinical evaluation, potential biomarkers, and current and proposed treatments for adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), a rare, debilitating, and life-threatening neurodegenerative disorder for which disease-modifying therapies are not currently available. Details on potential efficacy endpoints for future interventional clinical trials in patients with ALSP and data related to the burden of the disease on patients and caregivers were also reviewed. The information in this position paper lays a foundation to establish an effective clinical rationale and address the clinical gaps for creation of a robust strategy to develop therapeutic agents for ALSP, as well as design future clinical trials, that have clinically meaningful and convergent endpoints.

Oxidative Stress Biomarkers and Mitochondrial DNA Copy Number Associated with APOE4 Allele and Cholinesterase Inhibitor Therapy in Patients with Alzheimer's Disease

Studies of the oxidative/anti-oxidative status in patients with Alzheimer’s disease (AD) carrying different alleles of the apolipoprotein E (APOE) gene are currently inconclusive; meanwhile, data regarding mitochondrial DNA copy number (mtCN) remain limited. We herein determined the thiobarbituric acid reactive substances (TBARS), thiols, and mtCN in blood samples of 600 AD patients and 601 controls. A significantly higher oxidative TBARS (1.64 μmol/L), lower antioxidative thiols (1.60 μmol/L), and lower mtCN (2.34 log Delta Ct) were found in the AD cohort as compared to the non-AD cohort (1.54 μmol/L, 1.71 μmol/L, 2.46 log Delta Ct). We further identified the ε4 alleles (APOE4) and separated subjects into three groups according to the number of APOE4. A significant trend was noted in the TBARS levels of both AD and non-AD cohorts, highest in the homozygous two alleles (1.86 and 1.80 μmol/L), followed by heterozygous one allele (1.70 and 1.74 μmol/L), and lowest in the no APOE4 allele (1.56 and 1.48 μmol/L). Similar trends of lower thiols and mtCN were also found in the AD cohort. In our study of the influence of cholinesterase inhibitor therapy, we found significantly reduced TBARS levels, and elevated mtCN in AD patients receiving rivastigmine and galantamine therapy. Our study demonstrates associations between the APOE4 allele and oxidative stress biomarkers and mtCN. Using cholinesterase inhibitor therapy may benefit AD patients through attenuation of oxidative stress and manipulation of the mtCN.

Biomedical Applications and Bioavailability of Curcumin-An Updated Overview

Curcumin, a yellow-colored molecule derived from the rhizome of Curcuma longa, has been identified as the bioactive compound responsible for numerous pharmacological activities of turmeric, including anticancer, antimicrobial, anti-inflammatory, antioxidant, antidiabetic, etc. Nevertheless, the clinical application of curcumin is inadequate due to its low solubility, poor absorption, rapid metabolism and elimination. Advancements in recent research have shown several components and techniques to increase the bioavailability of curcumin. Combining with adjuvants, encapsulating in carriers and formulating in nanoforms, in combination with other bioactive agents, synthetic derivatives and structural analogs of curcumin, have shown increased efficiency and bioavailability, thereby augmenting the range of applications of curcumin. The scope for incorporating biotechnology and nanotechnology in amending the current drawbacks would help in expanding the biomedical applications and clinical efficacy of curcumin. Therefore, in this review, we provide a comprehensive overview of the plethora of therapeutic potentials of curcumin, their drawbacks in efficient clinical applications and the recent advancements in improving curcumin's bioavailability for effective use in various biomedical applications.

Mild Cognitive Impairment and Donepezil Impact Mitochondrial Respiratory Capacity in Skeletal Muscle

Alzheimer's Disease (ad) associates with insulin resistance and low aerobic capacity, suggestive of impaired skeletal muscle mitochondrial function. However, this has not been directly measured in AD. This study ( n  = 50) compared muscle mitochondrial respiratory function and gene expression profiling in cognitively healthy older adults (CH; n = 24) to 26 individuals in the earliest phase of ad-related cognitive decline, mild cognitive impairment (MCI; n  = 11) or MCI taking the ad medication donepezil (MCI + med; n  = 15). Mitochondrial respiratory kinetics were measured in permeabilized muscle fibers from muscle biopsies of the vastus lateralis. Untreated MCI exhibited lower lipid-stimulated skeletal muscle mitochondrial respiration (State 3, ADP-stimulated) than both CH ( P = .043) and MCI + med (P = .007) groups. MCI also exhibited poorer mitochondrial coupling control compared to CH (P = .014). RNA sequencing of skeletal muscle revealed unique differences in mitochondrial function and metabolism genes based on both MCI status (CH vs MCI) and medication treatment (MCI vs MCI + med). MCI + med modified over 600 skeletal muscle genes compared to MCI suggesting donepezil powerfully impacts the transcriptional profile of muscle. Overall, skeletal muscle mitochondrial respiration is altered in untreated MCI but normalized in donepezil-treated MCI participants while leak control is impaired regardless of medication status. These results provide evidence that mitochondrial changes occur in the early stages of AD, but are influenced by a common ad medicine. Further study of mitochondrial bioenergetics and the influence of transcriptional regulation in early ad is warranted.

Recent Updates in the Alzheimer's Disease Etiopathology and Possible Treatment Approaches: A Narrative Review of Current Clinical Trials

BACKGROUND

Alzheimer's disease (AD) is the most frequent subtype of incurable neurodegenerative dementias and its etiopathology is still not clearly elucidated.

OBJECTIVE

Outline the ongoing clinical trials (CTs) in the field of AD, in order to find novel master regulators.

METHODS

We strictly reviewed all scientific reports from Clinicaltrials.gov and PubMed databases from January 2010 to January 2019. The search terms were "Alzheimer's disease" or "dementia" and "medicine" or "drug" or "treatment" and "clinical trials" and "interventions". Manuscripts that met the objective of this study were included for further evaluations.

RESULTS

Drug candidates have been categorized into two main groups including antibodies, peptides or hormones (such as Ponezumab, Interferon β-1a, Solanezumab, Filgrastim, Levemir, Apidra, and Estrogen), and naturally-derived ingredients or small molecules (such as Paracetamol, Ginkgo, Escitalopram, Simvastatin, Cilostazo, and Ritalin-SR). The majority of natural candidates acted as anti-inflammatory or/and anti-oxidant and antibodies exert their actions via increasing amyloid-beta (Aβ) clearance or decreasing Tau aggregation. Among small molecules, most of them that are present in the last phases act as specific antagonists (Suvorexant, Idalopirdine, Intepirdine, Trazodone, Carvedilol, and Risperidone) or agonists (Dextromethorphan, Resveratrol, Brexpiprazole) and frequently ameliorate cognitive dysfunctions.

CONCLUSION

The presences of a small number of candidates in the last phase suggest that a large number of candidates have had an undesirable side effect or were unable to pass essential eligibility for future phases. Among successful treatment approaches, clearance of Aβ, recovery of cognitive deficits, and control of acute neuroinflammation are widely chosen. It is predicted that some FDA-approved drugs, such as Paracetamol, Risperidone, Escitalopram, Simvastatin, Cilostazoand, and Ritalin-SR, could also be used in off-label ways for AD. This review improves our ability to recognize novel treatments for AD and suggests approaches for the clinical trial design for this devastating disease in the near future.

Significant effects of cholinesterase inhibitors on tau pathology in the Alzheimer's disease continuum: An in vivo positron emission tomography study

OBJECTIVES

No prior study has assessed the effects of cholinesterase inhibitors (ChEIs) on tau pathology in the brains of patients with Alzheimer's disease (AD). Using positron emission tomography, this study aimed to investigate whether ChEIs reduce tau aggregation in amyloid-positive participants.

METHODS

We analyzed datasets from the Alzheimer's Disease Neuroimaging Initiative and included amyloid-positive participants who had undergone baseline and 1- or 2-year follow-up AV-1451 positron emission tomography scans. We included participants treated with and without ChEIs (ChEIs group: n = 15, No-ChEIs group, n = 45). The annual change in tau aggregation was calculated as the difference in AV-1451- standardized uptake value ratio (SUVR) between the two scans divided by the time between scans. Group differences in annual AV-1451-SUVR change were examined.

RESULTS

We found a significantly lower annual change in AV-1451-SUVR in the Braak 1/2 regions (entorhinal cortex and hippocampus) of participants taking ChEIs. Increased AV-1451-SUVR between the first and second examinations were observed in 22 of 45 participants not taking ChEIs and 2 of 15 participants taking ChEIs. Fisher's exact test showed a significant difference in the ratio of participants with increased AV-1451-SUVR between the groups.

CONCLUSIONS

The findings of this positron emission tomography study suggest that the administration of ChEIs has some neuroprotective effects in patients of the AD continuum, at least in the early stage of the disease progression. This in vivo effect may be mediated via tau, preventing amyloid β-induced neurotoxicity.

Donepezil Protects Against Doxorubicin-Induced Chemobrain in Rats via Attenuation of Inflammation and Oxidative Stress Without Interfering With Doxorubicin Efficacy

Although doxorubicin (Dox) is an effective chemotherapy medication used extensively in the treatment of breast cancer, it frequently causes debilitating neurological deficits known as chemobrain. Donepezil (DPZ), an acetylcholinesterase inhibitor, provides therapeutic benefits in various neuropathological conditions. However, comprehensive mechanistic insights regarding the neuroprotection of DPZ on cognition and brain pathologies in a Dox-induced chemobrain model remain obscure. Here, we demonstrated that Dox-treated rats manifested conspicuous cognitive deficits and developed chemobrain pathologies as indicated by brain inflammatory and oxidative insults, glial activation, defective mitochondrial homeostasis, increased potential lesions associated with Alzheimer's disease, disrupted neurogenesis, loss of dendritic spines, and ultimately neuronal death through both apoptosis and necroptosis. Intervention with DPZ co-treatment completely restored cognitive function by attenuating these pathological conditions induced by DOX. We also confirmed that DPZ treatment does not affect the anti-cancer efficacy of Dox in breast cancer cells. Together, our findings suggest that DPZ treatment confers potential neuroprotection against Dox-induced chemobrain.

Subcommissural Organ-Spondin-Derived Peptide Restores Memory in a Mouse Model of Alzheimer's Disease

Alzheimer’s disease (AD) is a devastating neurodegenerative disease that affects millions of older people worldwide and is characterized by a progressive deterioration of cognitive functions, including learning and memory. There are currently very few approved treatments (i.e., acetylcholinesterase inhibitors such as donepezil), all of which are limited to the symptomatic control of AD and are associated with side effects that may result in discontinuation of treatment. Therefore, there is an urgent need to develop disease-modifying treatments to prevent AD-induced cognitive deficits. Subcommissural organ (SCO)-spondin is a brain-specific glycoprotein produced during embryogenesis and has a substantial impact on neuronal development. In the current study, we sought to evaluate the protective effects of the linear (NX210) and cyclized (NX210c) forms of a SCO-spondin-derived peptide on learning and memory in a mouse model of AD. Mice received an intracerebroventricular injection of Aβ_25–35 oligomers and were subsequently treated with intraperitoneal injections of vehicle, NX210 or NX210c of different doses (ranging from 0.1 to 30 mg/kg) and therapy paradigms (early or late stand-alone treatments, combination with donepezil or second-line treatment). Cognitive function was evaluated using Y-Maze, step-through latency passive avoidance (STPA) and Morris water maze (MWM) tests for up to 4 months. Early stage daily treatment with NX210 and NX210c decreased the levels of common pathological markers and features of AD, including Aβ_1–42, phosphorylated-tau, inflammation, astrogliosis and lipid peroxidation. Meanwhile, use of these drugs increased the levels of synaptophysin and postsynaptic density protein 95. Regardless of the experimental paradigm used, NX210 and NX210c prevented Aβ_25–35-induced decrease in spontaneous alternations (Y-Maze) and step-through latency into the dark compartment (STPA), and Aβ_25–35-induced increase in time needed to locate the immersed platform during the learning phase and decrease in time spent in the target quadrant during the retention phase (MWM). Interestingly, this study provides the novel evidence that the native and oxidized cyclic forms of the SCO-spondin-derived peptide reduce pathological factors associated with AD and restore learning and memory at both early and late disease stages. Overall, this study sheds light on the therapeutic potential of this innovative disease-modifying peptide to restore memory function in patients with AD.

Blood-brain barrier dysfunction as a potential therapeutic target for neurodegenerative disorders

The blood-brain barrier (BBB) is composed of specific tight junction proteins and transporters expressed on the lining of endothelial cells of the vasculature in the brain. The structural and functional integrity of the BBB is one of the most critical factors for maintaining brain homeostasis and is mainly regulated by complex interactions between various cell types, such as endothelial cells, pericytes, and astrocytes, which are shaped by their differential responses to changes in microenvironments. Alterations in these cellular components have been implicated in neurodegenerative disorders. Although it has long been considered that BBB dysfunction is a mere ramification of pathological phenomena, emerging evidence supports its critical role in the pathogenesis of various disorders. In epilepsy, heightened BBB permeability has been found to be associated with increased occurrence of spontaneous seizures. Additionally, exaggerated inflammatory responses significantly correlate with increased BBB permeability during healthy aging. Furthermore, it has been previously reported that BBB disruption can be an early marker for predicting cognitive impairment in the progression of Alzheimer's disease. We herein review a potential role of the major cellular components of the BBB, with a focus on the contribution of BBB disruption, in neurodegenerative disease progression.

Shenqi Yizhi Granule attenuates Aβ1-42 induced cognitive dysfunction via inhibiting JAK2/STAT3 activated astrocyte reactivity

Shenqi Yizhi Granule (SYG), a modern preparation herbs based on the theory of traditional Chinese medicine, has been proved to be effective against Alzheimer's disease in clinical trials, APP/PS1 mice and 5XFAD transgenic mice. But the underlying mechanism remains ambiguous. Increasing evidence supports the crucial role of astrocyte reactivity in the pathogenesis of Alzheimer's disease (AD). In the present study, we attempt to explore the underlying mechanisms of SYG from astrocyte reactivity in Aβ_1-42-induced rat model of Alzheimer's disease. After SYG treatment, the impairment of learning and memory induced by Aβ_1-42 was significantly improved and the hippocampal neuron damages were alleviated. Additionally, the activity of glutamine synthetase and the concentration of glutamate, which might be involved in the cognitive dysfunctions, were outstandingly reduced. Meanwhile, the astrocyte reactivity was also remarkably inhibited. The expressions of JAK2 and STAT3, key proteins in the JAK2/STAT3 signaling pathway that is tightly associated with reactive astrocytes, were clearly attenuated, too. Collectively, our data demonstrate that SYG might exert protective effects on cognitive impairment induced by amyloid-β oligomers via inhibition of astrocyte reactivity regulated by the JAK2/STAT3 signaling pathway. It may be a potential therapeutic for cognitive dysfunctions in many neurological and psychiatric disorders such as Alzheimer's disease.

Autonomic and cholinergic mechanisms mediating cardiovascular and temperature effects of donepezil in conscious mice

Donepezil is a centrally acting acetylcholinesterase (AChE) inhibitor with therapeutic potential in inflammatory diseases; however, the underlying autonomic and cholinergic mechanisms remain unclear. Here, we assessed effects of donepezil on mean arterial pressure (MAP), heart rate (HR), HR variability, and body temperature in conscious adult male C57BL/6 mice to investigate the autonomic pathways involved. Central versus peripheral cholinergic effects of donepezil were assessed using pharmacological approaches including comparison with the peripherally acting AChE inhibitor, neostigmine. Drug treatments included donepezil (2.5 or 5 mg/kg sc), neostigmine methyl sulfate (80 or 240 μg/kg ip), atropine sulfate (5 mg/kg ip), atropine methyl bromide (5 mg/kg ip), or saline. Donepezil, at 2.5 and 5 mg/kg, decreased HR by 36 ± 4% and 44 ± 3% compared with saline (n = 10, P < 0.001). Donepezil, at 2.5 and 5 mg/kg, decreased temperature by 13 ± 2% and 22 ± 2% compared with saline (n = 6, P < 0.001). Modest (P < 0.001) increases in MAP were observed with donepezil after peak bradycardia occurred. Atropine sulfate and atropine methyl bromide blocked bradycardic responses to donepezil, but only atropine sulfate attenuated hypothermia. The pressor response to donepezil was similar in mice coadministered atropine sulfate; however, coadministration of atropine methyl bromide potentiated the increase in MAP. Neostigmine did not alter HR or temperature, but did result in early increases in MAP. Despite the marked bradycardia, donepezil did not increase normalized high-frequency HR variability. We conclude that donepezil causes marked bradycardia and hypothermia in conscious mice via the activation of muscarinic receptors while concurrently increasing MAP via autonomic and cholinergic pathways that remain to be elucidated.

Acetylcholinesterase inhibitors targeting the cholinergic anti-inflammatory pathway: a new therapeutic perspective in aging-related disorders

Neuroinflammation and cholinergic dysfunction, leading to cognitive impairment, are hallmarks of aging and neurodegenerative disorders, including Alzheimer's disease (AD). Acetylcholinesterase inhibitors (AChEI), the symptomatic therapy in AD, attenuate and delay the cognitive deficit by enhancing cholinergic synapses. The α7 nicotinic acetylcholine (ACh) receptor has shown a double-edged sword feature, as it binds with high affinity Aβ_1-42, promoting intracellular accumulation and Aβ-induced tau phosphorylation, but also exerts neuroprotection by stimulating anti-apoptotic pathways. Moreover, it mediates peripheral and central anti-inflammatory response, being the effector player of the activation of the cholinergic anti-inflammatory pathway (CAIP), that, by decreasing the release of TNF-α, IL-1β, and IL-6, it may have a role in improving cognition. The finding in preclinical models that, in addition to their major function (choline esterase inhibition) AChEIs have neuroprotective properties mediated via α7nAChR and modulate innate immunity, possibly as a result of the increased availability of acetylcholine activating the CAIP, pave the way for new pharmacological intervention in AD and other neurological disorders that are characterized by neuroinflammation. CHRFAM7A is a human-specific gene acting as a dominant negative inhibitor of α7nAChR function, also suggesting a role in affecting human cognition and memory by altering α7nAChR activities in the central nervous system (CNS). This review will summarize the current knowledge on the cholinergic anti-inflammatory pathway in aging-related disorders, and will argue that the presence of the human-restricted CHRFAM7A gene might play a fundamental role in the regulation of CAIP and in the response to AChEI.

Connecting vascular aging and frailty in Alzheimer's disease

Aging plays an important role in the etiology of the most common age-related diseases (ARDs), including Alzheimer's disease (AD). The increasing number of AD patients and the lack of disease-modifying drugs warranted intensive research to tackle the pathophysiological mechanisms underpinning AD development. Vascular aging/dysfunction is a common feature of almost all ARDs, including cardiovascular (CV) diseases, diabetes and AD. To this regard, interventions aimed at modifying CV outcomes are under extensive investigation for their pleiotropic role in ameliorating and slowing down cognitive impairment in middle-life and elderly individuals. Evidence from observational and clinical studies confirm the notion that the earlier the interventions are conducted, the most favorable are the effects on cognitive function. Therefore, epidemiological research should focus on the early detection of deviations from a healthy cognitive aging trajectory, through the stratification of adult individuals according to the rate of aging. Here, we review the interplay between vascular and cognitive dysfunctions associated with aging, to disentangle the complex mechanisms underpinning the development and progression of neurodegenerative disorders, with a specific focus on AD.

Neuroprotective effects of maize tetrapeptide-anchored gold nanoparticles in Alzheimer's disease

Nanopeptide assembled from peptide-anchored nanoparticles possess an enormous research potential in the field of cellular medicine and disease treatment. The aim of this study was to explore the neuroprotective effects of maize tetrapeptide anchored gold nanoparticles against l-glutamic acid-induced PC12 cell apoptosis and a murine Alzheimer's disease model induced by aluminum chloride and d-galactose. The results revealed that the nanopeptide antioxidant inhibited intracellular ROS accumulation and promoted cell differentiation than that of maize bioactive tetrapeptide. Compared with untreated Alzheimer's disease model mice, nanopeptide administration shortened the escape latency time in a water maze test and improved the movements in the autonomic activity test. After 16 days of nanopeptide administration, the central cholinergic system function of acetylcholine and cholineacetyltransferase were enhanced, and the level of acetylcholinesterase was reduced. It also increased superoxide dismutase and glutathione peroxidase activity in sera and hypothalami. Moreover, nanopeptide treatment upregulated cerebral nuclear factor erythroid 2-related factor 2 and heme-oxygenase-1 and downregulated kelch-like ECH-associated protein 1 relative to untreated Alzheimer's disease model mice. Thus, the novel nanopeptide is expected to be used as the neuroprotective agent to prevent Alzheimer's disease.

Chronic BACE-1 Inhibitor Administration in TASTPM Mice (APP KM670/671NL and PSEN1 M146V Mutation): An EEG Study

OBJECTIVE

In this exploratory study, we tested whether electroencephalographic (EEG) rhythms may reflect the effects of a chronic administration (4 weeks) of an anti-amyloid β-site amyloid precursor protein (APP) cleaving enzyme 1 inhibitor (BACE-1; ER-901356; Eisai Co., Ltd., Tokyo, Japan) in TASTPM (double mutation in APP KM670/671NL and PSEN1 M146V) producing Alzheimer's disease (AD) amyloid neuropathology as compared to wild type (WT) mice.

METHODS

Ongoing EEG rhythms were recorded from a bipolar frontoparietal and two monopolar frontomedial (prelimbic) and hippocampal channels in 11 WT Vehicle, 10 WT BACE-1, 10 TASTPM Vehicle, and 11 TASTPM BACE-1 mice (males; aged 8/9 months old at the beginning of treatment). Normalized EEG power (density) was compared between the first day (Day 0) and after 4 weeks (Week 4) of the BACE-1 inhibitor (10 mg/Kg) or vehicle administration in the 4 mouse groups. Frequency and magnitude of individual EEG delta and theta frequency peaks (IDF and ITF) were considered during animal conditions of behaviorally passive and active wakefulness. Cognitive status was not tested.

RESULTS

Compared with the WT group, the TASTPM group generally showed a significantly lower reactivity in frontoparietal ITF power during the active over the passive condition (p < 0.05). Notably, there was no other statistically significant effect (e.g., additional electrodes, recording time, and BACE-1 inhibitor).

CONCLUSIONS

The above EEG biomarkers reflected differences between the WT and TASTPM groups, but no BACE-1 inhibitor effect. The results suggest an enhanced experimental design with the use of younger mice, longer drug administrations, an effective control drug, and neuropathological amyloid markers.

Efficacy of acetylcholinesterase inhibitors in Alzheimer's disease

Alzheimer's disease (AD), the most common cause of adult-onset dementia is characterized by a progressive decline of cognitive functions accompanied by behavioral manifestations. The main class of drugs currently used for the treatment of AD are acetylcholinesterase/cholinesterase inhibitors (ChE-Is). The first ChE-I licensed for symptomatic treatment of AD was tacrine. The ChE-Is currently available in the market are donepezil, rivastigmine and galantamine as tacrine is no longer in use, due to its hepatotoxicity. According to mechanism of action the ChE-Is are classified as short-acting or reversible agents such as tacrine, donepezil, and galantamine, as intermediate-acting or pseudo-irreversible agent such as rivastigmine. Overall, the efficacy of the three ChE-Is available in the market is similar and the benefit of administration of these compounds is mild and may not be clinically significant. Due to gastrointestinal side effects of these drugs, medicinal chemistry and pharmaceutical delivery studies have investigated solutions to improve the pharmacological activity of these compounds. In spite of the limited activity of ChE-Is, waiting for more effective approaches, these drugs still represent a pharmacotherapeutic resource for the treatment of AD. Other approaches in which ChE-Is were investigated is in their use in combination with other classes of drugs such as cholinergic precursors, N-methyl-d-aspartate (NMDA) receptor antagonists and antioxidant agents. After many years from the introduction in therapy of ChE-Is, the combination with other classes of drugs may represent the chance for a renewed interest of ChE-Is in the treatment of adult-onset dementia disorders.

Donepezil provides neuroprotective effects against brain injury and Alzheimer's pathology under conditions of cardiac ischemia/reperfusion injury

Cardiac ischemia/reperfusion (I/R) injury induces brain pathology. Donepezil, a well-known acetylcholine esterase (AChE) inhibitor, has been proven to exert neuroprotective effects against several neurodegenerative diseases. However, the comprehensive mechanism regarding the therapeutic potential of donepezil on the brain under cardiac I/R injury remains obscure. Here, we hypothesized that treatment with donepezil ameliorates brain pathology following cardiac I/R injury by decreasing blood brain barrier (BBB) breakdown, oxidative stress, neuroinflammation, mitochondrial dysfunction, mitochondrial dynamics imbalance, microglial activation, amyloid-beta (Aβ) accumulation, neuronal apoptosis, and dendritic spine loss. Forty-eight adult male Wistar rats were subjected to surgery for cardiac I/R injury. Then, rats were randomly divided into four groups to receive either (1) saline (vehicle group), donepezil 3 mg/kg via intravenously administered (2) before ischemia (pretreatment group), (3) during ischemia (ischemia group), or (4) at the onset of reperfusion (reperfusion group). At the end of cardiac I/R paradigm, the brains were evaluated for BBB breakdown, brain inflammation, oxidative stress, mitochondrial function, mitochondrial dynamics, microglial morphology, Aβ production, neuronal apoptosis, and dendritic spine density. Administration of donepezil at all time points equally showed an attenuation of brain damage in response to cardiac I/R injury, as indicated by increased expression of BBB junction protein, reduced brain inflammation and oxidative stress, improved mitochondrial function and mitochondrial dynamics, and alleviated Aβ accumulation and microglial activation, resulting in protection of neuronal apoptosis and preservation of dendritic spine number. These findings suggest that donepezil potentially protects brain pathology caused by cardiac I/R injury regardless the timing of treatment.

Expression of miR-28-3p in patients with Alzheimer's disease before and after treatment and its clinical value

Expression of miR-28-3p in patients with Alzheimer's disease (AD) before and after treatment and clinical value of miR-28-3p were determined. There were three groups: 68 AD patients treated with donepezil combined with basic therapy in The People's Hospital of Shouguang collected as an AD group, 70 patients with mild cognitive impairment (MCI) as an MCI group, and 75 healthy people as a normal group. Serum miR-28-3p was detected by qRT-PCR. The Montreal cognitive assessment scale (MoCA), mini mental state examination scale (MMSE), activities of daily living scale (ADL) and homocysteine (Hcy) were adopted to assess patients before and after treatment. miR-28-3p in normal group was significantly lower than that in other two groups, and miR-28-3p in MCI group was significantly lower than that in AD group (P<0.001). miR-28-3p correlated with the course and severity of patients. miR-28-3p in AD group after treatment was significantly lower than that before treatment (P<0.001). ADL and Hcy of AD patients after treatment were significantly lower than before treatment (P<0.05), and MMSE and MoCA after treatment were significantly higher than before treatment (P<0.05). Before and after treatment, miR-28-3p was significantly positively correlated with ADL score and Hcy level, but negatively correlated with MMSE score and MoCA score. Analysis of the working characteristic curve of the patients indicated that miR-28-3p can be used for diagnosis of AD patients. Donepezil therapy may reduce miR-28-3p level to alleviate the symptoms of AD patients, and miR-28-3p level can be used as an early diagnosis and prognosis evaluation of AD patients.

Evaluation of the neuroprotective effect of donepezil in type 2 diabetic rats

Recent studies raise the possibility that donepezil can delay the progression of Alzheimer's disease (AD). This research evaluated the efficacy of donepezil in an animal model with brain insulin resistance and AD-like alterations. Rats were fed with high-fat/high-fructose (HF/Hfr) diet during the study period (17 weeks) and received one injection of streptozotocin (STZ) (25 mg/kg) after 8 weeks of starting the study. Diabetic (T2D) rats were treated with donepezil (4 mg/kg; p.o.) or vehicle for 8 weeks after STZ injection. The influence of donepezil on AD-related behavioral, biochemical, and neuropathological changes was investigated in T2D rats. Treatment of diabetic rats with donepezil led to a significant decrease in both amyloid-β deposition and the raised hippocampal activity of cholinesterase (ChE). It significantly increased the suppressed glutamate receptor expression (AMPA GluR1 subunit and NMDA receptor subunits NR1, NR2A, NR2B). It also improved cognitive dysfunction in the passive avoidance and the Morris water maze tests. However, donepezil treatment did not significantly decrease the elevated levels of P-tau, caspase-3, GSK-3β, MDA, TNF-α, and IL-1β in the hippocampus of diabetic rats. Also, it did not restore the suppressed levels of glutathione and superoxide dismutase in the brain of these rats. Moreover, donepezil did not alter the elevated serum level of glucose, insulin, and total cholesterol. These findings suggest that donepezil treatment could ameliorate learning and memory impairment in T2D rats through reversal of some of the AD-related alterations, including reduction of amyloid-β burden and ChE activity as well as restoration of glutamate receptor expression. However, lack of any significant effect on P-tau load, oxidative stress, neuroinflammation, and insulin resistance raises the question about the ability of donepezil to delay the development or arrest the progression of T2D-induced AD and it is still a matter of debate that requires further studies.

Capgras Delusion in Posterior Cortical Atrophy-A Quantitative Multimodal Imaging Single Case Study

Although Alzheimer’s disease presents homogeneous histopathology, it causes several clinical phenotypes depending on brain regions involved. Beside the most abundant memory variant, several atypical variants exist. Among them posterior cortical atrophy (PCA) is associated with severe visuospatial/visuoperceptual deficits in the absence of significant primary ocular disease. Here, we report for the first time a case of Capgras delusion—a delusional misidentification syndrome, where patients think that familiar persons are replaced by identical “doubles” or an impostor—in a patient with PCA. The 57-year-old female patient was diagnosed with PCA and developed Capgras delusion 8 years after first symptoms. The patient did not recognize her husband, misidentified him as a stranger, and perceived him as a threat. Such misidentifications did not happen for other persons. Events could be interrupted by reassuring the husband’s identity by the patient’s female friend or children. We applied in-depth multimodal neuroimaging phenotyping and used single-subject voxel-based morphometry to identify atrophy changes specifically related to the development of the Capgras delusion. The latter, based on structural T1 magnetic resonance imaging, revealed progressive gray matter volume decline in occipital and temporoparietal areas, involving more the right than the left hemisphere, especially at the beginning. Correspondingly, the right fusiform gyrus was already affected by atrophy at baseline, whereas the left fusiform gyrus became involved in the further disease course. At baseline, glucose hypometabolism as measured by positron emission tomography (PET) with F18-fluorodesoxyglucose (FDG-PET) was evident in the parietooccipital cortex, more pronounced right-sided, and in the right frontotemporal cortex. Amyloid accumulation as assessed by PET with F18-florbetaben was found in the gray matter of the neocortex indicating underlying Alzheimer’s disease. Appearance of the Capgras delusion was related to atrophy in the right posterior cingulate gyrus/precuneus, as well as right middle frontal gyrus/frontal eye field, supporting right frontal areas as particularly relevant for Capgras delusion. Atrophy in these regions respectively might affect the default mode and dorsal attention networks as shown by meta-analytical co-activation and resting state functional connectivity analyses. This case elucidates the brain-behavior relationship in PCA and Capgras delusion.

Pharmacological signatures of the reduced incidence and the progression of cognitive decline in ageing populations suggest the protective role of beneficial polypharmacy

Preventive treatments for dementia are warranted. Here we show that utilization of certain combinations of prescription medications and supplements correlates with reduced rates of cognitive decline. More than 1,900 FDA-approved agents and supplements were collapsed into 53 mechanism-based groups and traced in electronic medical records (EMRs) for >50,000 patients. These mechanistic groups were aligned with the data presented in more than 300 clinical trials, then regression model was built to fit the signals from EMRs to clinical trial performance. While EMR signals of each single agents correlated with clinical performance relatively weakly, the signals produced by combinations of active compounds were highly correlated with the clinical trial performance (R = 0.93, p = 3.8 x10^-8). Higher ranking pharmacological modalities were traced in patient profiles as their combinations, producing protective complexity estimates reflecting degrees of exposure to beneficial polypharmacy. For each age strata, the higher was the protective complexity score, the lower was the prevalence of dementia, with maximized life-long effects for the highest regression score /diversity compositions. The connection was less strong in individuals already diagnosed with cognitive impairment. Confounder analysis confirmed an independent effect of protective complexity in multivariate context. A sub-cohort with lifelong odds of dementia decreased > 5-folds was identified; this sub-cohort should be studied in further details, including controlled clinical trials. In short, our study systematically explored combinatorial preventive treatment regimens for age-associated multi-morbidity, with an emphasis on neurodegeneration, and provided extensive evidence for their feasibility.

Potential therapeutic roles of retinoids for prevention of neuroinflammation and neurodegeneration in Alzheimer's disease

All retinoids, which can be natural and synthetic, are chemically related to vitamin A. Both natural and synthetic retinoids use specific nuclear receptors such as retinoic acid receptors and retinoid X receptors to activate specific signaling pathways in the cells. Retinoic acid signaling is extremely important in the central nervous system. Impairment of retinoic acid signaling pathways causes severe pathological processes in the central nervous system, especially in the adult brain. Retinoids have major roles in neural patterning, differentiation, axon outgrowth in normal development, and function of the brain. Impaired retinoic acid signaling results in neuroinflammation, oxidative stress, mitochondrial malfunction, and neurodegeneration leading to progressive Alzheimer's disease, which is pathologically characterized by extra-neuronal accumulation of amyloid plaques (aggregated amyloid-beta) and intra-neurofibrillary tangles (hyperphosphorylated tau protein) in the temporal lobe of the brain. Alzheimer's disease is the most common cause of dementia and loss of memory in old adults. Inactive cholinergic neurotransmission is responsible for cognitive deficits in Alzheimer's disease patients. Deficiency or deprivation of retinoic acid in mice is associated with loss of spatial learning and memory. Retinoids inhibit expression of chemokines and neuroinflammatory cytokines in microglia and astrocytes, which are activated in Alzheimer's disease. Stimulation of retinoic acid receptors and retinoid X receptors slows down accumulation of amyloids, reduces neurodegeneration, and thereby prevents pathogenesis of Alzheimer's disease in mice. In this review, we described chemistry and biochemistry of some natural and synthetic retinoids and potentials of retinoids for prevention of neuroinflammation and neurodegeneration in Alzheimer's disease.