Anticholinergic effect of resveratrol with vitamin E on scopolamine-induced Alzheimer's disease in rats: Mechanistic approach to prevent inflammation

Beyond the blur: Scopolamine's utility and limits in modeling cognitive disorders across sexes - Narrative review

Scopolamine, widely regarded as the gold standard in preclinical studies of memory impairments, acts as a non-selective antagonist of central and peripheral muscarinic receptors. While its application in modeling dementia primarily involves antagonism at the M1 receptor, its non-selective peripheral actions may introduce adverse effects that influence behavioral test outcomes. This review analyzes preclinical findings to consolidate knowledge on scopolamine's use and elucidate potential mechanisms responsible for its amnestic effects. We focused on recognition, spatial, and emotional memory processes, alongside executive functions such as attention, cognitive flexibility, and working memory. The cognitive effects of scopolamine are highly dose-dependent, influenced by factors such as species, age, and sex of subjects. Notably, scopolamine rapidly induces observable memory impairments across species, from fish to rodents and primates, often with deficits that can persist for days. However, the compound's broad action on muscarinic receptors and its peripheral side effects, including pupil dilation and reduced salivation, complicates result interpretation, particularly in tasks requiring visual discrimination or food intake. The review also highlights scopolamine's translational value in modeling dementia and Alzheimer's disease, emphasizing the importance of considering individual factors and task-specific designs. Despite its widespread use, scopolamine's limited specificity for cholinergic dysfunction and inability to fully mimic the complex pathophysiology of cognitive disorders like Alzheimer's and Parkinson's disease point to the need for complementary models. This review aims to guide researchers in using scopolamine for modeling cognitive impairments, ensuring attention to factors impacting experimental outcomes.

Resveratrol-Loaded Pluronic Micelles Ameliorate Scopolamine-Induced Cognitive Dysfunction Targeting Acetylcholinesterase Activity and Programmed Cell Death

Numerous experimental studies suggest the potential for resveratrol (RVT) to be useful in the Alzheimer's disease treatment, but its low bioavailability limits its application. This study aimed to assess the potential of resveratrol-loaded micelles as a neuronal delivery platform to protect rats from scopolamine-induced memory impairment. Resveratrol was incorporated into Pluronic micelles, and the effects of micellar (mRVT) and pure resveratrol (RVT) were compared in the model of scopolamine-induced dementia in male Wistar rats. Memory performance was assessed by a T maze test. The effect of the treatment on specific neurotransmitter levels and protein expression in the cortex and the hippocampus were evaluated biochemically. Our results revealed that the polymeric micelles were in nanoscale (approximately 33 nm) and reached 79% encapsulation efficiency. The treatment with mRVT demonstrated better spatial memory protective effect. The biochemical assays showed that mRVT in a dose of 10 mg/kg enhanced the effects of the pure drug in regard to noradrenalin neurotransmission and acetylcholinesterase inhibitory activity in the hippocampus. Furthermore, micellar resveratrol increased the cAMP-response element-binding protein expression in the cortex and hippocampus of rats as well as the Bcl2/BAX ratio, which indicated an anti-apoptotic effect in the experimental dementia model. In conclusion, our results indicated the potential of a micellar system loaded with resveratrol for neurodegenerative diseases treatment.

Duguetia furfuracea (A.ST. Hil.) Saff.: Neuroprotective Effect on Chemically Induced Amnesia, Anxiolytic Effects and Preclinical Safety Evaluation in Mice

Duguetia furfuracea, "araticum-seco", is known to contain several bioactive compounds that can mitigate oxidative stress and act on the central nervous system (CNS). This effect is partly attributed to its potent antioxidant and acetylcholinesterase (AChE) inhibitors. In this study, the effects were explored of the methanolic extract (MEDF) and alkaloid fraction (AFDF) of D. furfuracea (leaves) on cognitive behaviors in male mice with scopolamine (Scop)-induced cognitive impairment and biochemical parameters. Additionally, anxiolytic behavior, subacute toxicity, molecular docking and antioxidant activity were reported. MEDF (30, 100 or 300 mg/kg) or AFDF (30 mg/kg) were orally administered for 16 days and Scop (intraperitoneally, i.p.) between days 11 and 16. The anxiolytic behavior (open field test and marble burying) in healthy mice, and the Scop-induced memory impairment (object recognition test and Morris water maze (MWM)) were assessed, and the biochemical parameters (malondialdehyde (MDA) and AChE levels) were measured after euthanasia. The subacute toxicological impact of MEDF was assessed in female Swiss mice for 28 days. MEDF and AFDF were available for the DPPH, ABTS and β-carotene/linoleic acid models. The results revealed that MEDF and AFDF exhibit anxiolytic effects and significantly alleviated Sco-induced memory impairment, inhibited AChE in the cortex (40%) and MDA (51.51%) levels. Reticuline was reported in AFDF and molecular coupling with AChE involves link-type hydrogen bonds and van der Waals interactions. MEDF exhibited antioxidant capacity (DPPH, IC50 = 18.10 ± 1.70 µg/mL; ABTS, IC50 = 10.41 ± 1.69 µg/mL). MEDF did not reveal signs of toxicity. In conclusion, D. furfuracea shows promise in mitigating scopolamine-induced memory deficits, potentially because it inhibits AChE activity, reduces MDA levels, and enhances antioxidant activities.

Analysis of Differential microRNA Expression in the Hippocampus of Scopolamine-Induced Amnesic Mouse Model

Amnesia is characterized by memory deficits linked to various neurodegenerative pathologies and can be induced by the administration of scopolamine, a cholinergic antagonist. Scopolamine-induced amnesia is a well-studied pharmacological animal model that simulates memory impairment caused by aging, brain illnesses, neuropathologies, and trauma. However, the molecular mechanism of amnesia, more importantly in terms of microRNA (miRNA) regulation, is not well understood. Therefore, this study aimed to analyze miRNA profiles in the hippocampus of both control mice and those treated with scopolamine (amnesic mice). Initially, a short cDNA library was prepared for each sample and then sequenced on the Illumina platform. Among the total differentially expressed miRNAs, 113 were significantly upregulated and 96 were downregulated in the scopolamine group in comparison to the control group. Ten upregulated and ten downregulated miRNAs were validated to confirm the reliability of the sequencing results using qRT-PCR (quantitative real-time PCR). Furthermore, we performed a target prediction analysis intersecting the results from TargetScan, miRDB (miRNA database), and Miranda to analyze the targets of the dysregulated miRNAs. We also conducted a pathway analysis to investigate the molecular, cellular, and biological functions of these targets. miRNA‒target interactions were found to play roles in various signaling pathways during amnesia. These results provide an initial insight for the contribution of miRNAs to scopolamine-induced amnesia, as well as their possible application as markers of disease pathology.

Caloric restriction mimetics improve gut microbiota: a promising neurotherapeutics approach for managing age-related neurodegenerative disorders

The gut microbiota (GM) produces various molecules that regulate the physiological functionality of the brain through the gut-brain axis (GBA). Studies suggest that alteration in GBA may lead to the onset and progression of various neurological dysfunctions. Moreover, aging is one of the prominent causes that contribute to the alteration of GBA. With age, GM undergoes a shift in population size and species of microflora leading to changes in their secreted metabolites. These changes also hamper communications among the HPA (hypothalamic-pituitary-adrenal), ENS (enteric nervous system), and ANS (autonomic nervous system). A therapeutic intervention that has recently gained attention in improving health and maintaining communication between the gut and the brain is calorie restriction (CR), which also plays a critical role in autophagy and neurogenesis processes. However, its strict regime and lifelong commitment pose challenges. The need is to produce similar beneficial effects of CR without having its rigorous compliance. This led to an exploration of calorie restriction mimetics (CRMs) which could mimic CR's functions without limiting diet, providing long-term health benefits. CRMs ensure the efficient functioning of the GBA through gut bacteria and their metabolites i.e., short-chain fatty acids, bile acids, and neurotransmitters. This is particularly beneficial for elderly individuals, as the GM deteriorates with age and the body's ability to digest the toxic accumulates declines. In this review, we have explored the beneficial effect of CRMs in extending lifespan by enhancing the beneficial bacteria and their effects on metabolite production, physiological conditions, and neurological dysfunctions including neurodegenerative disorders.

Alzheimer's disease: a review on the current trends of the effective diagnosis and therapeutics

The most prevalent cause of dementia is Alzheimer's disease. Cognitive decline and accelerating memory loss characterize it. Alzheimer's disease advances sequentially, starting with preclinical stages, followed by mild cognitive and/or behavioral impairment, and ultimately leading to Alzheimer's disease dementia. In recent years, healthcare providers have been advised to make an earlier diagnosis of Alzheimer's, prior to individuals developing Alzheimer's disease dementia. Regrettably, the identification of early-stage Alzheimer's disease in clinical settings can be arduous due to the tendency of patients and healthcare providers to disregard symptoms as typical signs of aging. Therefore, accurate and prompt diagnosis of Alzheimer's disease is essential in order to facilitate the development of disease-modifying and secondary preventive therapies prior to the onset of symptoms. There has been a notable shift in the goal of the diagnosis process, transitioning from merely confirming the presence of symptomatic AD to recognizing the illness in its early, asymptomatic phases. Understanding the evolution of disease-modifying therapies and putting effective diagnostic and therapeutic management into practice requires an understanding of this concept. The outcomes of this study will enhance in-depth knowledge of the current status of Alzheimer's disease's diagnosis and treatment, justifying the necessity for the quest for potential novel biomarkers that can contribute to determining the stage of the disease, particularly in its earliest stages. Interestingly, latest clinical trial status on pharmacological agents, the nonpharmacological treatments such as behavior modification, exercise, and cognitive training as well as alternative approach on phytochemicals as neuroprotective agents have been covered in detailed.

Pharmacological insights and role of bufalin (bufadienolides) in inflammation modulation: a narrative review

Bufadienolides, specifically bufalin, have garnered attention for their potential therapeutic application in modulating inflammatory pathways. Bufalin is derived from toad venom and exhibits promising anti-inflammatory properties. Its anti-inflammatory effects have been demonstrated by influencing crucial signaling pathways like NF-B, MAPK, and JAK-STAT, resulting in the inhibition of pro-inflammatory substances like cytokines, chemokines, and adhesion molecules. Bufalin blocks inflammasome activation and reduces oxidative stress, hence increasing its anti-inflammatory properties. Bufalin has shown effectiveness in reducing inflammation-related diseases such as cancer, cardiovascular problems, and autoimmune ailments in preclinical investigations. Furthermore, producing new approaches of medication delivery and combining therapies with bufalin shows potential for improving its effectiveness and reducing adverse effects. This review explores the pharmacological effects and mechanistic approaches of bufalin as an anti-inflammatory agent, which further highlights its potential for therapy and offers the basis for further study on its therapeutic application in inflammation-related disorders.

Natural Bioactive Compounds from Macroalgae and Microalgae for the Treatment of Alzheimer's Disease: A Review

Neuroinflammation, toxic protein aggregation, oxidative stress, and mitochondrial dysfunction are key pathways in neurodegenerative diseases like Alzheimer's disease (AD). Targeting these mechanisms with antioxidants, anti-inflammatory compounds, and inhibitors of Aβ formation and aggregation is crucial for treatment. Marine algae are rich sources of bioactive compounds, including carbohydrates, phenolics, fatty acids, phycobiliproteins, carotenoids, fatty acids, and vitamins. In recent years, they have attracted interest from the pharmaceutical and nutraceutical industries due to their exceptional biological activities, which include anti-inflammation, antioxidant, anticancer, and anti-apoptosis properties. Multiple lines of evidence have unveiled the potential neuroprotective effects of these multifunctional algal compounds for application in treating and managing AD. This article will provide insight into the molecular mechanisms underlying the neuroprotective effects of bioactive compounds derived from algae based on in vitro and in vivo models of neuroinflammation and AD. We will also discuss their potential as disease-modifying and symptomatic treatment strategies for AD.

Ginkgo biloba: A Leaf of Hope in the Fight against Alzheimer's Dementia: Clinical Trial Systematic Review

Alzheimer's disease (AD) is a stealthy and progressive neurological disorder that is a leading cause of dementia in the global elderly population, imposing a significant burden on both the elderly and society. Currently, the condition is treated with medications that alleviate symptoms. Nonetheless, these drugs may not consistently produce the desired results and can cause serious side effects. Hence, there is a vigorous pursuit of alternative options to enhance the quality of life for patients. Ginkgo biloba (GB), an herb with historical use in traditional medicine, contains bioactive compounds such as terpenoids (Ginkgolides A, B, and C), polyphenols, organic acids, and flavonoids (quercetin, kaempferol, and isorhamnetin). These compounds are associated with anti-inflammatory, antioxidant, and neuroprotective properties, making them valuable for cognitive health. A systematic search across three databases using specific keywords-GB in AD and dementia-yielded 1702 documents, leading to the selection of 15 clinical trials for synthesis. In eleven studies, GB extract/EGb 761® was shown to improve cognitive function, neuropsychiatric symptoms, and functional abilities in both dementia types. In four studies, however, there were no significant differences between the GB-treated and placebo groups. Significant improvements were observed in scores obtained from the Mini-Mental State Examination (MMSE), Short Cognitive Performance Test (SKT), and Neuropsychiatric Inventory (NPI). While the majority of synthesized clinical trials show that Ginkgo biloba has promising potential for the treatment of these conditions, more research is needed to determine optimal dosages, effective delivery methods, and appropriate pharmaceutical formulations. Furthermore, a thorough assessment of adverse effects, exploration of long-term use implications, and investigation into potential drug interactions are critical aspects that must be carefully evaluated in future studies.

Cumulative Anticholinergic Burden and its Predictors among Older Adults with Alzheimer's Disease Initiating Cholinesterase Inhibitors

BACKGROUND

Cumulative anticholinergic burden refers to the cumulative effect of multiple medications with anticholinergic properties. However, concomitant use of cholinesterase inhibitors (ChEIs) and anticholinergic burden can nullify the benefit of the treatment and worsen Alzheimer's disease (AD). A literature gap exists regarding the extent of the cumulative anticholinergic burden and associated risk factors in AD. Therefore, this study evaluated the prevalence and predictors of cumulative anticholinergic burden among patients with AD initiating ChEIs.

METHODS

A retrospective longitudinal cohort study was conducted using the Medicare claims data involving parts A, B, and D from 2013 to 2017. The study sample included older adults (65 years and older) diagnosed with AD and initiating ChEIs (donepezil, rivastigmine, or galantamine). The cumulative anticholinergic burden was calculated based on the Anticholinergic Cognitive Burden scale and patient-specific dosing using the defined daily dose over the 1 year follow-up period after ChEI initiation. Incremental anticholinergic burden levels were dichotomized into moderate-high (sum of standardized daily anticholinergic exposure over a year (TSDD) score ≥ 90) versus low-no (score 0-89). The Andersen Behavioral Model was used as the conceptual framework for selecting the predictors under the predisposing, enabling, and need categories. A multivariable logistic regression model was used to evaluate the predictors of high-moderate versus low-no cumulative anticholinergic burden. A multinomial logistic regression model was also used to determine the factors associated with patients having moderate and high burdens compared to low/no burdens.

RESULTS

The study included 222,064 older adults with AD with incident ChEI use (mean age 82.24 ± 7.29, 68.9% females, 83.6% White). Overall, 80.48% had some anticholinergic burden during the follow-up, with 36.26% patients with moderate (TSDD scores 90-499), followed by 24.76% high (TSDD score > 500), and 19.46% with low (TSDD score 1-89) burden categories. Predisposing factors such as age; African American, Asian, or Hispanic race; and need factors included comorbidities such as dyslipidemia, syncope, delirium, fracture, pneumonia, epilepsy, and claims-based frailty index were less likely to be associated with the moderate-high anticholinergic burden. The factors that increased the odds of moderate-high burden were predisposing factors such as female sex; enabling factors such as dual eligibility and diagnosis year; and need factors such as baseline burden, behavioral and psychological symptoms of dementia, depression, insomnia, urinary incontinence, irritable bowel syndrome, anxiety, muscle spasm, gastroesophageal reflux disease, heart failure, and dysrhythmia. Most of these findings remained consistent with multinomial logistic regression.  CONCLUSION: Four out of five older adults with AD had some level of anticholinergic burden, with over 60% having moderate-high anticholinergic burden. Several predisposing, enabling, and need factors were associated with the cumulative anticholinergic burden. The study findings suggest a critical need to minimize the cumulative anticholinergic burden to improve AD care.

Cross Talks between CNS and CVS Diseases: An Alliance to Annihilate

Cardiovascular and neurological diseases cause substantial morbidity and mortality globally. Moreover, cardiovascular diseases are the leading cause of death globally. About 17.9 million people are affected by cardiovascular diseases and 6.8 million people die every year due to neurological diseases. The common neurologic manifestations of cardiovascular illness include stroke syndrome which is responsible for unconsciousness and several other morbidities significantly diminished the quality of life of patients. Therefore, it is prudent need to explore the mechanistic and molecular connection between cardiovascular disorders and neurological disorders. The present review emphasizes the association between cardiovascular and neurological diseases specifically Parkinson's disease, Alzheimer's disease, and Huntington's disease.

Effects of Tiliroside and Lisuride Co-Treatment on the PI3K/Akt Signal Pathway: Modulating Neuroinflammation and Apoptosis in Parkinson's Disease

Researchers are actively exploring potential bioactive compounds to enhance the effectiveness of Lisuride (Lis) in treating Parkinson's disease (PD) over the long term, aiming to mitigate the serious side effects associated with its extended use. A recent study found that combining the dietary flavonoid Tiliroside (Til) with Lis has potential anti-Parkinson's benefits. The study showed significant improvements in PD symptoms induced by 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) when Til and Lis were given together, based on various behavioral tests. This combined treatment significantly improved motor function and protected dopaminergic neurons in rats with PD induced by MPTP. It also activated important molecular pathways related to cell survival and apoptosis control, as indicated by the increased pAkt/Akt ratio. Til and Lis together increased B-cell lymphoma 2 (Bcl-2), decreased caspase 3 activity, and prevented brain cell decay. Co-administration also reduced tumor necrosis factor alpha (TNF-α) and Interleukin-1 (IL-1). Antioxidant markers such as superoxide dismutase (SOD), catalase, and reduced glutathione significantly improved compared to the MPTP-induced control group. This study shows that using Til and Lis together effectively treats MPTP-induced PD in rats, yielding results comparable to an 8 mg/kg dose of levodopa, highlighting their potential as promising Parkinson's treatments.

Effects of Vitamin E on the Gut Microbiome in Ageing and Its Relationship with Age-Related Diseases: A Review of the Current Literature

Ageing is inevitable in all living organisms and is associated with physical deterioration, disease and eventually death. Dysbiosis, which is the alteration of the gut microbiome, occurs in individuals during ageing, and plenty of studies support that gut dysbiosis is responsible for the progression of different types of age-related diseases. The economic burden of age-linked health issues increases as ageing populations increase. Hence, an improvement in disease prevention or therapeutic approaches is urgently required. In recent years, vitamin E has garnered significant attention as a promising therapeutic approach for delaying the ageing process and potentially impeding the development of age-related disease. Nevertheless, more research is still required to understand how vitamin E affects the gut microbiome and how it relates to age-related diseases. Therefore, we gathered and summarized recent papers in this review that addressed the impact of the gut microbiome on age-related disease, the effect of vitamin E on age-related disease along with the role of vitamin E on the gut microbiome and the relationship with age-related diseases which are caused by ageing. Based on the studies reported, different bacteria brought on various age-related diseases with either increased or decreased relative abundances. Some studies have also reported the positive effects of vitamin E on the gut microbiome as beneficial bacteria and metabolites increase with vitamin E supplementation. This demonstrates how vitamin E is vital as it affects the gut microbiome positively to delay ageing and the progression of age-related diseases. The findings discussed in this review will provide a simplified yet deeper understanding for researchers studying ageing, the gut microbiome and age-related diseases, allowing them to develop new preclinical and clinical studies.