Donepezil across the spectrum of Alzheimer's disease: dose optimization and clinical relevance

Rational Design of Dual-Functionalized Gd@C82 Nanoparticles to Relieve Neuronal Cytotoxicity in Alzheimer's Disease via Inhibition of Aβ Aggregation

The accumulation of amyloid-β (Aβ) peptides is a major hallmark of Alzheimer's disease (AD) and plays a crucial role in its pathogenesis. Particularly, the structured oligomeric species rich in β-sheet formations were implicated in neuronal organelle damage. Addressing this formidable challenge requires identifying candidates capable of inhibiting peptide aggregation or disaggregating preformed oligomers for effective antiaggregation-based AD therapy. Here, we present a dual-functional nanoinhibitor meticulously designed to target the aggregation driving force and amyloid fibril spatial structure. Leveraging the exceptional structural stability and facile tailoring capability of endohedral metallofullerene Gd@C82, we introduce desired hydrogen-binding sites and charged groups, which are abundant on its surface for specific designs. Impressively, these designs endow the resultant functionalized-Gd@C82 nanoparticles (f-Gd@C82 NPs) with high capability of redirecting peptide self-assembly toward disordered, off-pathway species, obstructing the early growth of protofibrils, and disaggregating the preformed well-ordered protofibrils or even mature Aβ fibrils. This results in considerable alleviation of Aβ peptide-induced neuronal cytotoxicity, rescuing neuronal death and synaptic loss in primary neuron models. Notably, these modifications significantly improved the dispersibility of f-Gd@C82 NPs, thus substantially enhancing its bioavailability. Moreover, f-Gd@C82 NPs demonstrate excellent cytocompatibility with various cell lines and possess the ability to penetrate the blood-brain barrier in mice. Large-scale molecular dynamics simulations illuminate the inhibition and disaggregation mechanisms. Our design successfully overcomes the limitations of other nanocandidates, which often overly rely on hydrophobic interactions or photothermal conversion properties, and offers a viable direction for developing anti-AD agents through the inhibition and even reversal of Aβ aggregation.

Pongamol Alleviates Neuroinflammation and Promotes Autophagy in Alzheimer's Disease by Regulating the Akt/mTOR Signaling Pathway

Alzheimer's disease (AD), one of the neurodegenerative disorders, is highly correlated with the abnormal hyperphosphorylation of Tau and aggregation of β-amyloid (Aβ). Oxidative stress, neuroinflammation, and abnormal autophagy are key drivers of AD and how they contribute to neuropathology remains largely unknown. The flavonoid compound pongamol is reported to possess a variety of pharmacological activities, such as antioxidant, antibacterial, and anti-inflammatory. This study investigated the neuroprotective effect and its mechanisms of pongamol in lipopolysaccharide (LPS)-induced BV2 cells, d-galactose/sodium nitrite/aluminum chloride (d-gal/NaNO2/AlCl3)-induced AD mice, and Caenorhabditis elegans models. Our research revealed that pongamol reduced the release of inflammatory factors IL-1β, TNF-α, COX-2, and iNOS in LPS-induced BV2 cells. Pongamol also protected neurons and significantly restored memory function, inhibited Tau phosphorylation, downregulated Aβ aggregation, and increased oxidoreductase activity in the hippocampus of AD mice. In addition, pongamol reversed the nuclear transfer of NF-κB and increased the levels of Beclin 1 and LC3 II/LC3 I. Most importantly, the anti-inflammatory and promoter autophagy effects of pongamol may be related to the regulation of the Akt/mTOR signaling pathway. In summary, these results showed that pongamol has a potential neuroprotective effect, which greatly enriched the research on the pharmacological activity of pongamol for improving AD.

Phytopharmaceuticals and Herbal Approaches to Target Neurodegenerative Disorders

Neurodegeneration is characterized as the continuous functional and structural loss of neurons, resulting in various clinical and pathological manifestations and loss of functional anatomy. Medicinal plants have been oppressed from ancient years and are highly considered throughout the world as a rich source of therapeutic means for the prevention, treatment of various ailments. Plant-derived medicinal products are becoming popular in India and other nations. Further herbal therapies shows good impact on chronic long term illnesses including degenerative conditions of neurons and brain. The use of herbal medicines continues to expand rapidly across the world. The active phytochemical constituents of individual plants are sometimes insufficient to achieve the desirable therapeutic effects. Combining the multiple herbs in a particular ratio (polyherbalism) will give a better therapeutic effect and reduce toxicity. Herbal-based nanosystems are also being studied as a way to enhance the delivery and bioavailability of phytochemical compounds for the treatment of neurodegenerative diseases. This review mainly focuses on the importance of the herbal medicines, polyherbalism and herbal-based nanosystems and its clinical significance for neurodegenerative diseases.

Effects of Donepezil on the Musculoskeletal System in Female Rats

The extension of human life makes it more and more important to prevent and treat diseases of the elderly, including Alzheimer's disease (AD) and osteoporosis. Little is known about the effects of drugs used in the treatment of AD on the musculoskeletal system. The aim of the present study was to investigate the effects of donepezil, an acetylcholinesterase inhibitor, on the musculoskeletal system in rats with normal and reduced estrogen levels. The study was carried out on four groups of mature female rats: non-ovariectomized (NOVX) control rats, NOVX rats treated with donepezil, ovariectomized (OVX) control rats and OVX rats treated with donepezil. Donepezil (1 mg/kg p.o.) was administered for four weeks, starting one week after the ovariectomy. The serum concentrations of CTX-I, osteocalcin and other biochemical parameters, bone mass, density, mineralization, histomorphometric parameters and mechanical properties, and skeletal muscle mass and strength were examined. Estrogen deficiency increased bone resorption and formation and worsened cancellous bone mechanical properties and histomorphometric parameters. In NOVX rats, donepezil decreased bone volume to tissue volume ratio in the distal femoral metaphysis, increased the serum phosphorus concentration and tended to decrease skeletal muscle strength. No significant bone effects of donepezil were observed in OVX rats. The results of the present study indicate slightly unfavorable effects of donepezil on the musculoskeletal system in rats with normal estrogen levels.

Treatment of Vascular and Neurodegenerative Forms of Cognitive Impairment and Dementias

Ideally, dementia care should be provided by a collaborative team. Eligible patients should be treated with the cognitive-enhancing medications, the cholinesterase inhibitors and memantine. For most of the common causes of dementia, there are no disease-modifying medications, with the exception that vascular dementia can be prevented by treating vascular risk factors to prevent stroke. There is hope that Alzheimer disease can be treated by using monoclonal antibodies that target amyloid beta, although more trials are needed. Holistic, patient-centered care can enhance quality and extend the time that the patient can live safely in the community.

[Russian experience in using a combination of fixed doses of donepezil and memantine in the treatment of Alzheimer's disease as an observational non-interventional multicenter program]

OBJECTIVE

To evaluate the efficacy, safety, and compliance to therapy with Mioreol, first used as part of routine clinical practice in patients with moderate-to-severe dementia due to AD.

MATERIAL AND METHODS

The study was conducted as a non-interventional observational program. The work was performed on a group of 48 patients with moderate-to-severe AD aged from 60 to 90 years (median age 74 [69; 77]). The therapeutic dose of Mioreol was 10 mg donepezil + 20 mg memantine, the drug was taken orally, once a day at the same time, regardless of meals. The duration of the course of therapy was 24 weeks. The effects of the drug were assessed using the MMSE, ADAS-Cog, NPI, and CGI scales before the start of therapy and by the end of 12 and 24 weeks of treatment.

RESULTS

The use of Mioreol in six-month therapy of AD patients with moderate-to-severe dementia improved not only cognitive but also a wide range of non-cognitive mental disorders. There was an improvement in the CGI-C scale in more than 50% of included patients, positive dynamics on the ADAS-cog scale (6.5 points reduction in total score) and reduction of non-cognitive mental disorders on the NPI scale (4 points reduction in total score).

CONCLUSION

Fixed-dose combination therapy with Mioreol is an effective and well-tolerated treatment option for patients with moderate-to-severe AD. A combination of fixed-dose therapeutic doses of donepezil and memantine is potentially more appropriate than the simultaneous use of two recommended drugs for the treatment of AD, which will improve treatment adherence in patients with moderate to severe AD.

Review of Alzheimer's disease drugs and their relationship with neuron-glia interaction

Alzheimer's disease (AD) is the most common cause of dementia worldwide. Because Alzheimer's disease has no known treatment, sufferers and their caregivers must concentrate on symptom management. Astrocytes and microglia are now known to play distinct physiological roles in synaptic function, the blood-brain barrier, and neurovascular coupling. Consequently, the search for drugs that can slow the degenerative process in dementia sufferers continues because existing drugs are designed to alleviate the symptoms of Alzheimer's disease. Drugs that address pathological changes without interfering with the normal function of glia, such as eliminating amyloid-beta deposits, are prospective treatments for neuroinflammatory illnesses. Because neuron-astrocytes-microglia interactions are so complex, developing effective, preventive, and therapeutic medications for AD will necessitate novel methodologies and strategic targets. This review focused on existing medications used in treating AD amongst which include Donepezil, Choline Alphoscerate, Galantamine, Dextromethorphan, palmitoylethanolamide, citalopram, resveratrol, and solanezumab. This review summarizes the effects of these drugs on neurons, astrocytes, and microglia interactions based on their pharmacokinetic properties, mechanism of action, dosing, and clinical presentations.

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.

Pharmacophore mapping of the crucial mediators of acetylcholinesterase and butyrylcholinesterase dual inhibition in Alzheimer's disease

Optimization and re-optimization of bioactive molecules using in silico methods have found application in the design of more active ones. Herein, we applied a pharmacophore modeling approach to screen potent dual inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) aimed at Alzheimer's disease (AD) treatment. The investigation entails molecular dynamics simulation, docking, pharmacophore modeling, drug-like screening, and binding energy analysis. We prepared a pharmacophore model from approved inhibitors of AChE and BuChE to predict the crucial moieties required for optimum molecular interaction with these proteins. The obtained pharmacophore model, used for database screening via some critical criteria, showed 229 hit molecules. Further analyses showed 42 likely dual inhibitors of AChE/BuChE with drug-like and pharmacokinetics properties the same as the approved cholinesterase inhibitors. Finally, we identified 14 dual molecules with improved potentials over the existing inhibitors and simulated ZINC92385797 bound to human AChE and BuChE structure after noticing that these 14 molecules are similar. The selected compound maintained relative stability at the active sites of both proteins over 120 ns simulation. Our integrated protocols showed the pertinent recipes of anti-AD drug design through the in silico pipeline.

Prescribing cholinesterase inhibitors in mild cognitive impairment-Observations from the Alzheimer's Disease Neuroimaging Initiative

INTRODUCTION

Analyses of off-label use of acetylcholinesterase inhibitors (AChEIs) in mild cognitive impairment (MCI) has produced mixed results. Post hoc analyses of observational cohorts, such as the Alzheimer's Disease Neuroimaging Initiative (ADNI), have reported deleterious effects in AChEI-treated subjects (AChEI+). Here, we used neuroimaging biomarkers to determine whether AChEI+ subjects had a greater rate of neurodegeneration than untreated (AChEI-) subjects while accounting for baseline differences.

METHODS

We selected 121 ADNI MCI AChEI+ subjects and 151 AChEI- subjects with a magnetic resonance imaging (MRI) scan; 82 AChEI+ and 110 AChEI- also had a fluorodeoxyglucose (FDG) scan. A subset (83 AChEI+ and 98 AChEI-) had cerebrospinal fluid (CSF) or amyloid positron emission tomography (PET) assessment for amyloid positivity. Linear regression models were used to compare the effect of treatment on changes in Mini-Mental State Examination and Clinical Dementia Rating-Sum of Boxes scores. We used standard regression in SPM (for baseline) and the SPM toolbox sandwich estimator, SwE (for longitudinal) for comparisons of AChEI+ and AChEI- FDG PET and MRI data.

RESULTS

At baseline, the AChEI+ group had significantly reduced cortical gray matter density (GMD) and more hypometabolism than AChEI- subjects. The greater rate of atrophy and hypometabolic changes over time in AChEI+ compared to AChEI- subjects did not survive correction for baseline differences. AChEI+ participants were more likely to be amyloid-positive and have lower GMD and FDG standardized uptake value ratio than AChEI- at baseline. AChEI+ subjects showed greater atrophy over time, which remained significant after controlling for amyloid status.

DISCUSSION

Our data suggest that the observed differences in rates of cognitive decline, atrophy, and hypometabolism are likely the result of significant baseline differences between the groups. Furthermore, the data indicate no treatment effect of AChEI (positive of negative), rather that physicians prescribe AChEI to subjects who present with more severe clinical impairment. This alone may account for the negative effect seen previously in the ADNI population of AChEI use among MCI subjects.

Effects of Body Weight on the Safety of High-Dose Donepezil in Alzheimer's Disease: Post hoc Analysis of a Multicenter, Randomized, Open-Label, Parallel Design, Three-Arm Clinical Trial

BACKGROUND

Donepezil 23 mg is considered for Alzheimer's disease (AD) to optimize cognitive benefits; however, increased adverse events (AEs) can negatively influence drug adherence. We investigated whether body weight (BW) differs based on the presence of AEs, and which baseline factors were relevant to the safety of high-dose donepezil.

METHODS

This study was a post hoc analysis of a multicenter randomized trial between 2014 and 2016. We included patients with moderate to severe AD treated with 10 mg/day of donepezil, and the daily dose was escalated to 23 mg with/without dose titration. Dose titration indicates 15 mg/day of donepezil before escalation or 10 mg and 23 mg/day on alternate days before escalation during the first 4 weeks. The patients were divided into 2 groups based on occurrence of AEs of special interest (AESIs) to compare baseline characteristics. We also assessed relationships between BW and AESIs.

RESULTS

Among the 160 participants in the safety population, the baseline BWs differed between the AESI (+) (n = 67) and AESI (-) (n = 93) groups. Baseline BW was inversely correlated with the occurrence of AESIs (p = 0.020), and this relationship was prominent in the no-dose titration group (p = 0.009) but absent in the dose-titration groups (p > 0.05).

CONCLUSIONS

BW is the most important factor that correlated with cholinergic AEs. Hence, stepwise dose titration should be considered, particularly in patients with low BW, to minimize the inverse relationship between BW and the occurrence of AEs ("Clinicaltrials.gov" No. NCT02550665 registered on September 15, 2015).

Mesenchymal stem cell therapies for Alzheimer's disease: preclinical studies

Alzheimer's disease (AD) is a chronic, progressive, and fatal neurodegenerative disorder that is characterized by memory failure, cognitive impairment, as well as behavioral and psychological manifestations. Drugs can only moderately manage, but not alleviate, clinical symptoms. Results, based on animal models, have demonstrated that cell therapy is a promising strategy for treating neurodegenerative disorders. The homing effect of mesenchymal stem cells (MSCs) replaces damaged cells, while some scholars believe that the paracrine effects play a crucial role in treating diseases. In fact, these cells have rich sources, exhibit high proliferation rates, low tumorigenicity, and immunogenicity, and have no ethical concerns. Consequently, MSCs have been used across various disease aspects, such as regulating immunity, nourishing nerves, and promoting regeneration. Deterioration of public health status have exposed both Alzheimer's patients and researchers to various difficulties during epidemics. In this review, we discuss the advances and challenges in the application of mesenchymal stem cell therapy for treatment of Alzheimer's disease.

Tailored Modeling of Rivastigmine Derivatives as Dual Acetylcholinesterase and Butyrylcholinesterase Inhibitors for Alzheimer's Disease Treatment

Rational modification of known drug candidates to design more potent ones using computational methods has found application in drug design, development, and discovery. Herein, we integrate computational and theoretical methodologies to unveil rivastigmine derivatives as dual inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) for Alzheimer's disease (AD) management. The investigation entails pharmacokinetics screening, density functional theory (DFT) mechanistic study, molecular docking, and molecular dynamics (MD) simulation. We designed over 20 rivastigmine substituents, subject them to some analyses, and identified RL2 with an appreciable blood-brain barrier score and no permeability glycoprotein binding. The compound shows higher acylation energy and a favored binding affinity to the cholinesterase enzymes. RL2 interacts with the AChE and BuChE active sites showing values of -41.1/-39.5 kcal mol^-1 while rivastigmine binds with -32.7/-30.7 kcal mol^-1 for these enzymes. The study revealed RL2 (4-fluorophenyl rivastigmine) as a potential dual inhibitor for AChE and BuChE towards Alzheimer's disorder management.

Effects of donepezil on the amplitude of low-frequency fluctuations in the brain of patients with Alzheimer's disease: evidence from resting-state functional magnetic resonance imaging

OBJECTIVES

To monitor the effects of donepezil on spontaneous neuronal activity (SNA), and the mechanisms underlying these effects in patients with mild-to-moderate Alzheimer's disease, using the amplitude of low-frequency fluctuations (ALFFs), a metric of resting-state functional MRI (rs-fMRI).

METHODS

Eleven patients with Alzheimer's disease were treated with donepezil for 6 months. Before and after treatment, the Mini-Mental State Examination (MMSE), Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog), Clinical Dementia Rating (CDR), Neuropsychiatric Inventory and Activities of Daily Living scores, along with rs-fMRI of patients were assessed. Eleven age-, sex-, and education-matched controls underwent MMSE and CDR assessments and rs-fMRI at enrollment. The ALFFs of the whole brain were obtained and compared between the groups.

RESULTS

Following donepezil treatment, MMSE scores increased (P = 0.043) and ADAS-cog scores decreased (P = 0.010). Regarding SNA post-treatment, ALFF increased significantly in the right triangular part of the inferior frontal gyrus (IFGtriang; P = 0.030; d = -0.595) and the right orbital part of the inferior frontal gyrus (P = 0.044; d = -0.628) and decreased significantly in the left medial orbital part of the superior frontal gyrus (P = 0.039; d = 0.606) and the right gyrus rectus (P = 0.010; d = 0.609). Furthermore, the changes in ADAS-cog scores from before to after treatment were positively correlated with the changes in ALFF in the right IFGtriang (r = 0.645; P = 0.032).

CONCLUSIONS

Donepezil improved SNA in the frontal lobe of patients with Alzheimer's disease. Therefore, ALFF was demonstrated to be a potential tool for assessing the effectiveness of Alzheimer's disease treatment.

Insulin Resistance as a Common Link Between Current Alzheimer's Disease Hypotheses

Almost 115 years ago, Alois Alzheimer described Alzheimer's disease (AD) for the first time. Since then, many hypotheses have been proposed. However, AD remains a severe health public problem. The current medical approaches for AD are limited to symptomatic interventions and the complexity of this disease has led to a failure rate of approximately 99.6%in AD clinical trials. In fact, no new drug has been approved for AD treatment since 2003. These failures indicate that we are failing in mimicking this disease in experimental models. Although most studies have focused on the amyloid cascade hypothesis of AD, the literature has made clear that AD is rather a multifactorial disorder. Therefore, the persistence in a single theory has resulted in lost opportunities. In this review, we aim to present the striking points of the long scientific path followed since the description of the first AD case and the main AD hypotheses discussed over the last decades. We also propose insulin resistance as a common link between many other hypotheses.

Exploring the feasibility of using real-world data from a large clinical data research network to simulate clinical trials of Alzheimer's disease

In this study, we explored the feasibility of using real-world data (RWD) from a large clinical research network to simulate real-world clinical trials of Alzheimer’s disease (AD). The target trial (i.e., NCT00478205) is a Phase III double-blind, parallel-group trial that compared the 23 mg donepezil sustained release with the 10 mg donepezil immediate release formulation in patients with moderate to severe AD. We followed the target trial’s study protocol to identify the study population, treatment regimen assignments and outcome assessments, and to set up a number of different simulation scenarios and parameters. We considered two main scenarios: (1) a one-arm simulation: simulating a standard-of-care (SOC) arm that can serve as an external control arm; and (2) a two-arm simulation: simulating both intervention and control arms with proper patient matching algorithms for comparative effectiveness analysis. In the two-arm simulation scenario, we used propensity score matching controlling for baseline characteristics to simulate the randomization process. In the two-arm simulation, higher serious adverse event (SAE) rates were observed in the simulated trials than the rates reported in original trial, and a higher SAE rate was observed in the 23 mg arm than in the 10 mg SOC arm. In the one-arm simulation scenario, similar estimates of SAE rates were observed when proportional sampling was used to control demographic variables. In conclusion, trial simulation using RWD is feasible in this example of AD trial in terms of safety evaluation. Trial simulation using RWD could be a valuable tool for post-market comparative effectiveness studies and for informing future trials’ design. Nevertheless, such an approach may be limited, for example, by the availability of RWD that matches the target trials of interest, and further investigations are warranted.

The seed oil of Paeonia ludlowii ameliorates Aβ25-35-induced Alzheimer's disease in rats

Paeonia ludlowii, a plant of the Paeoniaceae family, has abundant genetic diversity in different populations, and the seed oil can be used in a diverse number of activities. However, its neuroprotective effect is not clear. We investigated the memory-improving effects and associated mechanisms of Paeonia ludlowii seed oil (PLSO) on amyloid beta (Aβ)25-35-induced Alzheimer's disease (AD) in rats. The Morris water maze test was undertaken, and subsequently, the content of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and acetylcholinesterase (ACHE) in the hippocampus was detected by biochemical analyses. To further study PLSO, we examined the pathologic structure and apoptosis of hippocampal tissue by staining. Immunohistochemical analysis was used to detect expression of IBA-1 and GFAP in the hippocampus. Detection of proinflammatory factors was achieved by reverse transcription-quantitative polymerase chain reaction and Western blotting. High-dose PLSO inhibited expression of GFAP and IBA-1. We demonstrated that high-dose PLSO can regulate activation of glial cells and mediate apoptosis of hippocampal cells, and significantly improve learning and memory deficits in AD rats. PLSO could be developed as a nutritional supplement and sold as a drug for AD prevention and/or treatment.

Cholinergic System and Its Therapeutic Importance in Inflammation and Autoimmunity

Neurological and immunological signals constitute an extensive regulatory network in our body that maintains physiology and homeostasis. The cholinergic system plays a significant role in neuroimmune communication, transmitting information regarding the peripheral immune status to the central nervous system (CNS) and vice versa. The cholinergic system includes the neurotransmitter\ molecule, acetylcholine (ACh), cholinergic receptors (AChRs), choline acetyltransferase (ChAT) enzyme, and acetylcholinesterase (AChE) enzyme. These molecules are involved in regulating immune response and playing a crucial role in maintaining homeostasis. Most innate and adaptive immune cells respond to neuronal inputs by releasing or expressing these molecules on their surfaces. Dysregulation of this neuroimmune communication may lead to several inflammatory and autoimmune diseases. Several agonists, antagonists, and inhibitors have been developed to target the cholinergic system to control inflammation in different tissues. This review discusses how various molecules of the neuronal and non-neuronal cholinergic system (NNCS) interact with the immune cells. What are the agonists and antagonists that alter the cholinergic system, and how are these molecules modulate inflammation and immunity. Understanding the various functions of pharmacological molecules could help in designing better strategies to control inflammation and autoimmunity.

Design and Synthesis of Ranitidine Analogs as Multi-Target Directed Ligands for the Treatment of Alzheimer's Disease

The aggregation of amyloid β (Aβ) peptides and deposition of amyloid plaques are implicated in the pathogenesis of Alzheimer’s disease (AD). Therefore, blocking Aβ aggregation with small molecules has been proposed as one therapeutic approach for AD. In the present study, a series of ranitidine analogs containing cyclic imide isosteres were synthesized and their inhibitory activities toward Aβ aggregation were evaluated using in vitro thioflavin T assays. The structure–activity relationship revealed that the 1,8-naphthalimide moiety provided profound inhibition of Aβ aggregation and structural modifications on the other parts of the parent molecule (compound 6) maintained similar efficacy. Some of these ranitidine analogs also possessed potent inhibitory activities of acetylcholinesterase (AChE), which is another therapeutic target in AD. These ranitidine analogs, by addressing both Aβ aggregation and AChE, offer insight into the key chemical features of a new type of multi-target directed ligands for the pharmaceutical treatment of AD.

Preclinical systematic review of ginsenoside Rg1 for cognitive impairment in Alzheimer's disease

Ginseng has been used for the treatment of aging and memory impairment for thousands of years. Several studies have found that ginsenoside Rg1, as one of the main active components of ginseng, could potentially improve cognitive function in several different animal models. A preclinical systematic review to evaluate the efficacy and mechanisms of ginsenoside Rg1 for ameliorating cognitive impairments in Alzheimer's disease is reported here. We searched six databases from their inceptions to January 2019. Thirty-two studies were selected, which included a total of 1,643 animals. According to various cognitive behavioral tests, the results of the meta-analyses showed that ginsenoside Rg1 significantly improved cognitive behavioral impairments in most Alzheimer's disease models (P < 0.05), but there were no significant effects in animals with neuronal degeneration induced by chronic stress or in SAMP8 transgenic mice. The potential mechanisms included antioxidant and anti-inflammatory effects, amelioration of Alzheimer's disease-related pathology, synapse protection, and up-regulation of nerve cells via multiple signaling pathways.

The Role of Butyrylcholinesterase and Iron in the Regulation of Cholinergic Network and Cognitive Dysfunction in Alzheimer's Disease Pathogenesis

Alzheimer’s disease (AD), the most common form of dementia in elderly individuals, is marked by progressive neuron loss. Despite more than 100 years of research on AD, there is still no treatment to cure or prevent the disease. High levels of amyloid-β (Aβ) plaques and neurofibrillary tangles (NFTs) in the brain are neuropathological hallmarks of AD. However, based on postmortem analyses, up to 44% of individuals have been shown to have high Aβ deposits with no clinical signs, due to having a “cognitive reserve”. The biochemical mechanism explaining the prevention of cognitive impairment in the presence of Aβ plaques is still unknown. It seems that in addition to protein aggregation, neuroinflammatory changes associated with aging are present in AD brains that are correlated with a higher level of brain iron and oxidative stress. It has been shown that iron accumulates around amyloid plaques in AD mouse models and postmortem brain tissues of AD patients. Iron is required for essential brain functions, including oxidative metabolism, myelination, and neurotransmitter synthesis. However, an imbalance in brain iron homeostasis caused by aging underlies many neurodegenerative diseases. It has been proposed that high iron levels trigger an avalanche of events that push the progress of the disease, accelerating cognitive decline. Patients with increased amyloid plaques and iron are highly likely to develop dementia. Our observations indicate that the butyrylcholinesterase (BChE) level seems to be iron-dependent, and reports show that BChE produced by reactive astrocytes can make cognitive functions worse by accelerating the decay of acetylcholine in aging brains. Why, even when there is a genetic risk, do symptoms of the disease appear after many years? Here, we discuss the relationship between genetic factors, age-dependent iron tissue accumulation, and inflammation, focusing on AD.

Cholinergic Capsules and Academic Admonitions

Herein, I intend to capture highlights shared with my academic and research colleagues over the 60 years I devoted initially to my graduate and postdoctoral training and then to academic endeavors starting as an assistant professor in a new medical school at the University of California, San Diego (UCSD). During this period, the Department of Pharmacology emerged from a division within the Department of Medicine to become the first basic science department, solely within the School of Medicine at UCSD in 1979. As part of the school's plans to reorganize and to retain me at UCSD, I was appointed as founding chair. Some years later in 2002, faculty, led largely within the Department of Pharmacology and by practicing pharmacists within UCSD Healthcare, started the independent Skaggs School of Pharmacy and Pharmaceutical Sciences with a doctor of pharmacy (PharmD) program, where I served as the founding dean. My career pathway, from working at my family-owned pharmacy to chairing a department in a school of medicine and then becoming the dean of a school of pharmacy at a research-intensive, student-centered institution, involved some risky decisions. But the academic, curricular, and accreditation challenges posed were met by a cadre of creative faculty colleagues. I offer my experiences to individuals confronted with a multiplicity of real or imagined opportunities in academic health sciences, the related pharmaceutical industry, and government oversight agencies.

An acetylcholinesterase inhibitor, donepezil, increases anxiety and cortisol levels in adult zebrafish

BACKGROUND

A potent acetylcholinesterase inhibitor, donepezil is a cognitive enhancer clinically used to treat neurodegenerative diseases. However, its complete pharmacological profile beyond cognition remains unclear. The zebrafish (Danio rerio) is rapidly becoming a powerful novel model organism in neuroscience and central nervous system drug screening.

AIM

Here, we characterize the effects of 24-h donepezil administration on anxiety-like behavioral and endocrine responses in adult zebrafish.

METHODS

We evaluated zebrafish anxiety-like behaviors in the novel tank, the light-dark and the shoaling tests, paralleled by assessing brain acetylcholinesterase activity and whole-body cortisol levels.

RESULTS

Overall, donepezil dose-dependently decreased zebrafish locomotor activity in the novel tank test and reduced time in light in the light-dark test, likely representing hypolocomotion and anxiety-like behaviors. Donepezil predictably decreased brain acetylcholinesterase activity, also increasing whole-body cortisol levels, thus further linking acetylcholinesterase inhibition to anxiety-like behavioral and endocrine responses.

CONCLUSION

Collectively, these findings suggest negative modulation of zebrafish affective behavior by donepezil, support the key role of cholinergic mechanisms in behavioral regulation in zebrafish, and reinforce the growing utility of zebrafish models for studying complex behavioral processess and their neuroendocrine and neurochemical regulation.

Multi-target approach for Alzheimer's disease treatment: computational biomolecular modeling of cholinesterase enzymes with a novel 4-N-phenylaminoquinoline derivative reveal promising potentials

The identification of dual inhibitors targeting the active sites of the cholinesterase enzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), have lately surfaced as a multi-approach towards Alzheimer treatment. More recently, a novel series of 4-N-phenylaminoquinolines was synthesized and evaluated against AChE and BuChE in which one of the compounds displayed appreciable inhibition compared to the standard compound, galantamine. To provide a clearer picture of the inhibition mechanism of this potent compound at the molecular level, computational biomolecular modeling was carried out. The investigation was initiated with the exploration of the chemical properties of the identified compound 11 b and reference drug, galantamine. Density functional theory (DFT) calculations reveal some conceptual parameters that provide information on the stability and reactivity of the compounds as potential inhibitors. To unveil the binding mechanism, energetics and enzyme-ligand interactions, molecular dynamics (MD) simulations of six different systems were executed over a period. Calculated binding free energy values are in the same order with experimental IC₅₀ data. Identification of the main residues driving optimum binding of the active compound 11 b to the binding region of both AChE and BuChE showed Trp81 and Trp110 as the most important, respectively. It was proposed that the studied compound could serve as a dual inhibitor for AChE and BuChE, therefore, would potentially be a promising moiety in a multi-target approach for the treatment of Alzheimer's disorder.Communicated by Ramaswamy H. Sarma.

Geranylgeranyl acetone prevents glutamate-induced cell death in HT-22 cells by increasing mitochondrial membrane potential

Geranylgeranyl acetone (GGA) protects against various types of cell damages by upregulating heat shock proteins. We investigated whether GGA protects neuronal cells from cell death induced by oxidative stress. Glutamate exposure was lethal to HT-22 cells which comprise a neuronal line derived from mouse hippocampus. This configuration is often used as a model for hippocampus neurodegeneration in vitro. In the present study, GGA protected HT-22 cells from glutamate-induced oxidative stress. GGA pretreatment did not induce heat shock proteins (Hsps). Moreover, reactive oxygen species increased to the same extent in both GGA-pretreated and untreated cells exposed to glutamate. In contrast, glutamate exposure and GGA pretreatment increased mitochondrial membrane potential. However, increases in intracellular Ca²⁺ concentration were inhibited by GGA pretreatment. In addition, the increase of phosphorylated ERKs by the glutamate exposure was inhibited by GGA pretreatment. These findings suggest that GGA protects HT-22 cells from glutamate-provoked cell death without Hsp induction and that the mitochondrial calcium buffering capacity plays an important role in this protective effect.

Effects of α-Mangostin Derivatives on the Alzheimer's Disease Model of Rats and Their Mechanism: A Combination of Experimental Study and Computational Systems Pharmacology Analysis

α-Mangostin (α-M) is a natural xanthone from the pericarp of fruit Garcinia mangostana and possesses versatile biological activities. α-M has a therapeutic potential to treat Alzheimer's disease (AD) because of its anti-inflammatory, antioxidative, and neuroprotective activities. However, the use of α-M for AD treatment is limited due to its cytotoxic activities and relatively low potency. Modifications of its chemical structure were needed to reduce its cytotoxicity and improve its therapeutic potential against AD. For this purpose, 16 α-M carbamate derivatives were synthesized. An animal model of AD was established, and the effects of AMG-1 on the spatial learning ability and memory ability were evaluated using behavioral tests. The effect on neuropathology was tested by histopathological evaluation, Nissl staining, and silver staining. Computational systems pharmacology analysis using the chemogenomics knowledgebase was applied for network studies. Compound-target, target-pathway, and target-disease networks were constructed, integrating both in silico analysis and reported experimental data. The results show that AMG-1 can demonstrate its therapeutic effects in a one-molecule, multiple-targets manner to remarkably ameliorate neurological changes and reverse behavioral deficits in AD model rats. The improved cognitive function and alleviated neuronal injury can be observed. The ability of AMG-1 to scavenge β-amyloid in the hippocampus was validated in AD model rats.

Pharmacotherapy of Alzheimer's Disease: Seeking Clarity in a Time of Uncertainty

Alzheimer's disease (AD) is recognized as a major health hazard that mostly affects people older than 60 years. AD is one of the biggest medical, economic, and social concerns to patients and their caregivers. AD was ranked as the 5th leading cause of global deaths in 2016 by the World Health Organization (WHO). Many drugs targeting the production, aggregation, and clearance of Aβ plaques failed to give any conclusive clinical outcomes. This mainly stems from the fact that AD is not a disease attributed to a single-gene mutation. Two hallmarks of AD, Aβ plaques and neurofibrillary tangles (NFTs), can simultaneously induce other AD etiologies where every pathway is a loop of consequential events. Therefore, the focus of recent AD research has shifted to exploring other etiologies, such as neuroinflammation and central hyperexcitability. Neuroinflammation results from the hyperactivation of microglia and astrocytes that release pro-inflammatory cytokines due to the neurological insults caused by Aβ plaques and NFTs, eventually leading to synaptic dysfunction and neuronal death. This review will report the failures and side effects of many anti-Aβ drugs. In addition, emerging treatments targeting neuroinflammation in AD, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and receptor-interacting serine/threonine protein kinase 1 (RIPK1), that restore calcium dyshomeostasis and microglia physiological function in clearing Aβ plaques, respectively, will be deliberately discussed. Other novel pharmacotherapy strategies in treating AD, including disease-modifying agents (DMTs), repurposing of medications used to treat non-AD illnesses, and multi target-directed ligands (MTDLs) are also reviewed. These approaches open new doors to the development of AD therapy, especially combination therapy that can cater for several targets simultaneously, hence effectively slowing or stopping AD.

Recent strategies and advances in the fabrication of nano lipid carriers and their application towards brain targeting

In last two decades, the lipid nanocarriers have been extensively investigated for their drug targeting efficiency towards the critical areas of the human body like CNS, cardiac region, tumor cells, etc. Owing to the flexibility and biocompatibility, the lipid-based nanocarriers, including nanoemulsion, liposomes, SLN, NLC etc. have gained much attention among various other nanocarrier systems for brain targeting of bioactives. Across different lipid nanocarriers, NLC remains to be the safest, stable, biocompatible and cost-effective drug carrier system with high encapsulation efficiency. Drug delivery to the brain always remains a challenging issue for scientists due to the complex structure and various barrier mechanisms surrounding the brain. The application of a suitable nanocarrier system and the use of any alternative route of drug administration like nose-to-brain drug delivery could overcome the hurdle and improves the therapeutic efficiency of CNS acting drugs thereof. NLC, a second-generation lipid nanocarrier, upsurges the drug permeation across the BBB due to its unique structural properties. The biocompatible lipid matrix and nano-size make it an ideal drug carrier for brain targeting. It offers many advantages over other drug carrier systems, including ease of manufacturing and scale-up to industrial level, higher drug targeting, high drug loading, control drug release, compatibility with a wide range of drug substances, non-toxic and non-irritant behavior. This review highlights recent progresses towards the development of NLC for brain targeting of bioactives with particular reference to its surface modifications, formulations aspects, pharmacokinetic behavior and efficacy towards the treatment of various neurological disorders like AD, PD, schizophrenia, epilepsy, brain cancer, CNS infection (viral and fungal), multiple sclerosis, cerebral ischemia, and cerebral malaria. This work describes in detail the role and application of NLC, along with its different fabrication techniques and associated limitations. Specific emphasis is given to compile a summary and graphical data on the area explored by scientists and researchers worldwide towards the treatment of neurological disorders with or without NLC. The article also highlights a brief insight into two prime approaches for brain targeting, including drug delivery across BBB and direct nose-to-brain drug delivery along with the current global status of specific neurological disorders.

A Longitudinal Study of Epileptic Seizures in Alzheimer's Disease

The prevalence of epileptic seizures is increased in patients in the clinical stages of Alzheimer's disease (AD) when compared to age-matched cognitively normal populations. In previously reported work from the Presentation of Epileptic Seizures in Dementia (PrESIDe) study, we identified a clinical suspicion of epilepsy in between 12.75 and 28.43% of patients with AD recruited from a memory clinic. EEGs were not performed in this study. Patients with epilepsy performed similarly to patients without epilepsy on cognitive testing at the time of recruitment but were more impaired on two measures of everyday functioning [Cambridge Behavioral Inventory—Revised and Clinical Dementia Rating (CBI-R and CDR)]. On repeated testing in this 12-month follow-up study, patients in whom a suspicion of epilepsy was identified performed significantly worse on cognitive function testing (p = 0.028) in addition to maintaining a difference on the informant questionnaires (CBI-R p < 0.001, CDR p = 0.020). These findings suggest that seizures in this population could be a marker of a more rapid decline and worse prognosis.

A Systematic Review on Donepezil-based Derivatives as Potential Cholinesterase Inhibitors for Alzheimer’s Disease

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Alzheimer’s Disease (AD) is a multifactorial progressive neurodegenerative disorder characterized by memory loss, disorientation, and gradual deterioration of intellectual capacity. Its etiology has not been elucidated yet. To date, only one therapeutic approach has been approved for the treatment of AD. The pharmacotherapy of AD has relied on noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist - memantine, and acetylcholinesterase (AChE) inhibitors (AChEIs) - tacrine, donepezil, rivastigmine and galantamine. Donepezil was able to ameliorate the symptoms related to AD mainly via AChE, but also through reduction of β-amyloid burden. This review presents the overview of donepezilrelated compounds as potential anti-AD drugs developed on the basis of cholinergic hypothesis to act as solely AChE and butyrylcholinesterase (BChE) inhibitors.

Safety and tolerability of donepezil 23 mg with or without intermediate dose titration in patients with Alzheimer's disease taking donepezil 10 mg: a multicenter, randomized, open-label, parallel-design, three-arm, prospective trial

BACKGROUND

High-dose donepezil is currently prescribed for patients with Alzheimer's disease (AD) who showed poor or waning response to a lower dose at the risk of increasing cholinergic side effects. However, the adverse events (AEs) depending on the method of dose escalation have not been clarified yet. This study aimed to find out whether dose titration before escalating to donepezil 23 mg is preferred. We investigated safety and tolerability of donepezil 23 mg during the first 12 weeks of dose escalation in patients with moderate to severe AD.

METHODS

This study was a 12-week, multicenter, randomized, open-label prospective trial. We included patients with moderate to severe AD who were treated with a stable dose of donepezil 10 mg/day. Patients were randomized into 3 groups according to the dose escalation method: 15 mg of donepezil for 4 weeks before escalating to 23 mg (group 1), 10 mg and 23 mg on alternate days for 4 weeks prior to escalation (group 2), and direct escalation to 23 mg (group 3). Safety analyses included incidence, severity, timing of AEs, relationship to the study drug, and premature study discontinuation due to AEs between the groups.

RESULTS

Among 175 enrolled, 110 patients completed the study. Baseline characteristics were similar among the groups. Using safety population (N = 160), cholinergic gastrointestinal symptoms including anorexia and nausea were the most common AEs and titration groups showed significantly fewer cases of nausea as compared with those in no-titration group.

CONCLUSIONS

In this study, dose titration before escalating to donepezil 23 mg/day showed better safety in terms of cholinergic AEs. We suggest that dose titration during the first 4 weeks can be recommended for patients with moderate to severe AD.

TRIAL REGISTRATION

Clinicaltrials.gov , NCT02550665. Retrospectively registered on 15 Sep 2015.

Implications of Successful Symptomatic Treatment in Parkinson's Disease for Therapeutic Strategies of Alzheimer's Disease

Alzheimer's disease (AD) has been a devastating neurodegenerative disorder and lacks effective treatment to improve the prognosis for patients. Symptomatic treatment for AD mainly includes two categories: Acetylcholinesterase inhibitors and the N-methyl-d-aspartate (NMDA) receptor antagonist (memantine). They cannot significantly improve the quality of life and extend survival time for AD patients. Worse, almost all clinical trials for disease-modifying drugs have failed, and the reduction of brain β-amyloid (Aβ) deposition by multiple approaches, including inhibitors of β- or γ-secretase, vaccines, and antibodies against Aβ deposition, was found to have little effect on AD progression. A new therapeutic strategy for AD is urgently needed. Parkinson's disease also is a neurodegenerative disease having no effective treatment for modifying the disease. Nevertheless, successful symptomatic treatment using the combined therapies of l-DOPA supplement and modulators of l-DOPA metabolism greatly improves the prognosis for PD patients; the average survival time of the patient has been extended from 3-4 years to 10-15 years although dopaminergic neurons are still progressively decreasing. This provides useful implications for AD therapeutic strategies. AD patients manifest global cognitive decline, prominently represented by memory deficit, especially in the early stages of the disease. Further, the degree of decreased cognitive abilities correlates with cholinergic dysfunction and the hypometabolism of glucose, the dominant energy fuel for brain. Thus, the amelioration of brain cholinergic function and brain energy metabolism may be effective treatment to improve cognitive abilities of AD patients. Here, we highlighted the explorations of symptomatic therapeutics through modulating brain cholinergic function and energy metabolism in AD.

Traditional Chinese medicine-based neurorestorative therapy for Alzheimer’s and Parkinson’s disease

The prevalence of multiple neurodegenerative diseases, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD), has been dramatically increasing, particularly in the aging population. However, the currently available therapies merely alleviate the symptoms of these diseases and are unable to retard disease progression significantly. Traditional Chinese medicine (TCM) has been used in clinical practice for thousands of years for ameliorating symptoms or interfering with the pathogenesis of aging- associated diseases. Modern pharmacological studies have proved that TCM imparts disease-modifying therapeutic effects against these diseases, such as protection of neurons, clearance of protein aggregates, and regulation of neuroinflammation. This review summarizes the evidence from recent studies on AD and PD therapies regarding the neuroprotective activities and molecular mechanisms of a series of TCM formulations comprising herbs and their active ingredients. The findings of this review support the use of TCM as an alternative source of therapy for the treatment of neurodegenerative diseases.

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.

Comparative safety and effectiveness of cholinesterase inhibitors and memantine for Alzheimer's disease: a network meta-analysis of 41 randomized controlled trials

Background

Cholinesterase inhibitors and memantine have been approved for management of Alzheimer’s disease (AD), but there has been no consensus about the choice of various types and doses of drugs at different stages. Hence, we compared and ranked the efficacy and tolerability of these available drugs.

Methods

We searched PubMed, the Cochrane Central Register of Controlled Trials, and Embase for randomized controlled trials (RCTs) published from database inception to July 21, 2017. The primary outcomes were the mean overall changes in cognitive function and responders who had any adverse events. We conducted a random-effects network meta-analysis.

Results

Forty-one RCTs were included in this study. Compared with placebo, galantamine 32 mg daily (standardized mean difference – 0.51, 95% credible interval – 0.67 to − 0.35), galantamine 24 mg daily (− 0.50, − 0.61 to − 0.40), and donepezil 10 mg daily (− 0.40, − 0.51 to − 0.29) were probably the most effective agents on cognition for mild to moderate AD, and memantine 20 mg combined with donepezil 10 mg (0.76, 0.39 to 1.11) was recommended for moderate to severe patients. Memantine showed the best profile of acceptability. Rivastigmine transdermal 15-cm² patch was the best optional treatment both in function and global changes. None of the medicines was likely to improve neuropsychiatric symptoms through this analysis.

Conclusions

Pharmacological interventions have beneficial effects on cognition, function, and global changes, but not on neuropsychiatric symptoms, through current network meta-analysis. The choice of drugs may mainly depend on the disease severity and clinical symptoms.

Electronic supplementary material

The online version of this article (10.1186/s13195-018-0457-9) contains supplementary material, which is available to authorized users.

The exploration of novel Alzheimer's therapeutic agents from the pool of FDA approved medicines using drug repositioning, enzyme inhibition and kinetic mechanism approaches

Novel drug development is onerous, time consuming and overpriced process with particularly low success and relatively high enfeebling rates. To overcome this burden, drug repositioning approach is being used to predict the possible therapeutic effects of FDA approved drugs in different diseases. Herein, we designed a computational and enzyme inhibitory mechanistic approach to fetch the promising drugs from the pool of FDA approved drugs against AD. The binding interaction patterns and conformations of screened drugs within active region of AChE were confirmed through molecular docking profiles. The possible associations of selected drugs with AD genes were predicted by pharmacogenomics analysis and confirmed through data mining. The stability behaviour of docked complexes (Drugs-AChE) were checked by MD simulations. The possible therapeutic potential of repositioned drugs against AChE were checked by in vitro analysis. Taken together, Cinitapride displayed a comparable results with standard and can be used as possible therapeutic agent in the treatment of AD.

Neurodegenerative Diseases: Regenerative Mechanisms and Novel Therapeutic Approaches

Regeneration refers to regrowth of tissue in the central nervous system. It includes generation of new neurons, glia, myelin, and synapses, as well as the regaining of essential functions: sensory, motor, emotional and cognitive abilities. Unfortunately, regeneration within the nervous system is very slow compared to other body systems. This relative slowness is attributed to increased vulnerability to irreversible cellular insults and the loss of function due to the very long lifespan of neurons, the stretch of cells and cytoplasm over several dozens of inches throughout the body, insufficiency of the tissue-level waste removal system, and minimal neural cell proliferation/self-renewal capacity. In this context, the current review summarized the most common features of major neurodegenerative disorders; their causes and consequences and proposed novel therapeutic approaches.

Donepezil for dementia due to Alzheimer's disease

BACKGROUND

Alzheimer's disease is the most common cause of dementia in older people. One approach to symptomatic treatment of Alzheimer's disease is to enhance cholinergic neurotransmission in the brain by blocking the action of the enzyme responsible for the breakdown of the neurotransmitter acetylcholine. This can be done by a group of drugs known as cholinesterase inhibitors. Donepezil is a cholinesterase inhibitor.This review is an updated version of a review first published in 1998.

OBJECTIVES

To assess the clinical efficacy and safety of donepezil in people with mild, moderate or severe dementia due to Alzheimer's disease; to compare the efficacy and safety of different doses of donepezil; and to assess the effect of donepezil on healthcare resource use and costs.

SEARCH METHODS

We searched Cochrane Dementia and Cognitive Improvement's Specialized Register, MEDLINE, Embase, PsycINFO and a number of other sources on 20 May 2017 to ensure that the search was as comprehensive and up-to-date as possible. In addition, we contacted members of the Donepezil Study Group and Eisai Inc.

SELECTION CRITERIA

We included all double-blind, randomised controlled trials in which treatment with donepezil was administered to people with mild, moderate or severe dementia due to Alzheimer's disease for 12 weeks or more and its effects compared with those of placebo in a parallel group of patients, or where two different doses of donepezil were compared.

DATA COLLECTION AND ANALYSIS

One reviewer (JSB) extracted data on cognitive function, activities of daily living, behavioural symptoms, global clinical state, quality of life, adverse events, deaths and healthcare resource costs. Where appropriate and possible, we estimated pooled treatment effects. We used GRADE methods to assess the quality of the evidence for each outcome.

MAIN RESULTS

Thirty studies involving 8257 participants met the inclusion criteria of the review, of which 28 studies reported results in sufficient detail for the meta-analyses. Most studies were of six months' duration or less. Only one small trial lasted 52 weeks. The studies tested mainly donepezil capsules at a dose of 5 mg/day or 10 mg/day. Two studies tested a slow-release oral formulation that delivered 23 mg/day. Participants in 21 studies had mild to moderate disease, in five studies moderate to severe, and in four severe disease. Seventeen studies were industry funded or sponsored, four studies were funded independently of industry and for nine studies there was no information on source of funding.Our main analysis compared the safety and efficacy of donepezil 10 mg/day with placebo at 24 to 26 weeks of treatment. Thirteen studies contributed data from 3396 participants to this analysis. Eleven of these studies were multicentre studies. Seven studies recruited patients with mild to moderate Alzheimer's disease, two with moderate to severe, and four with severe Alzheimer's disease, with a mean age of about 75 years. Almost all evidence was of moderate quality, downgraded due to study limitations.After 26 weeks of treatment, donepezil compared with placebo was associated with better outcomes for cognitive function measured with the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-Cog, range 0 to 70) (mean difference (MD) -2.67, 95% confidence interval (CI) -3.31 to -2.02, 1130 participants, 5 studies), the Mini-Mental State Examination (MMSE) score (MD 1.05, 95% CI 0.73 to 1.37, 1757 participants, 7 studies) and the Severe Impairment Battery (SIB, range 0 to 100) (MD 5.92, 95% CI 4.53 to 7.31, 1348 participants, 5 studies). Donepezil was also associated with better function measured with the Alzheimer's Disease Cooperative Study activities of daily living score for severe Alzheimer's disease (ADCS-ADL-sev) (MD 1.03, 95% CI 0.21 to 1.85, 733 participants, 3 studies). A higher proportion of participants treated with donepezil experienced improvement on the clinician-rated global impression of change scale (odds ratio (OR) 1.92, 95% CI 1.54 to 2.39, 1674 participants, 6 studies). There was no difference between donepezil and placebo for behavioural symptoms measured by the Neuropsychiatric Inventory (NPI) (MD -1.62, 95% CI -3.43 to 0.19, 1035 participants, 4 studies) or by the Behavioural Pathology in Alzheimer's Disease (BEHAVE-AD) scale (MD 0.4, 95% CI -1.28 to 2.08, 194 participants, 1 study). There was also no difference between donepezil and placebo for Quality of Life (QoL) (MD -2.79, 95% CI -8.15 to 2.56, 815 participants, 2 studies).Participants receiving donepezil were more likely to withdraw from the studies before the end of treatment (24% versus 20%, OR 1.25, 95% CI 1.05 to 1.50, 2846 participants, 12 studies) or to experience an adverse event during the studies (72% vs 65%, OR 1.59, 95% 1.31 to 1.95, 2500 participants, 10 studies).There was no evidence of a difference between donepezil and placebo for patient total healthcare resource utilisation.Three studies compared donepezil 10 mg/day to donepezil 5 mg/day over 26 weeks. The 5 mg dose was associated with slightly worse cognitive function on the ADAS-Cog, but not on the MMSE or SIB, with slightly better QoL and with fewer adverse events and withdrawals from treatment. Two studies compared donepezil 10 mg/day to donepezil 23 mg/day. There were no differences on efficacy outcomes, but fewer participants on 10 mg/day experienced adverse events or withdrew from treatment.

AUTHORS' CONCLUSIONS

There is moderate-quality evidence that people with mild, moderate or severe dementia due to Alzheimer's disease treated for periods of 12 or 24 weeks with donepezil experience small benefits in cognitive function, activities of daily living and clinician-rated global clinical state. There is some evidence that use of donepezil is neither more nor less expensive compared with placebo when assessing total healthcare resource costs. Benefits on 23 mg/day were no greater than on 10 mg/day, and benefits on the 10 mg/day dose were marginally larger than on the 5 mg/day dose, but the rates of withdrawal and of adverse events before end of treatment were higher the higher the dose.

Silencing of LncRNA BDNF-AS attenuates Aβ25-35-induced neurotoxicity in PC12 cells by suppressing cell apoptosis and oxidative stress

OBJECTIVE

To explore the effects of long non-coding RNA (lncRNA) brain-derived neurotrophic factor anti-sense (BDNF-AS) on the Aβ_25-35-induced neurotoxicity in PC12 cells.

METHODS

PC12 cells were induced by Aβ_25-35 to construct cell injury models of Alzheimer's disease (AD), and then transfected with siRNA-BDNF-AS. Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to detect the expressions of BDNF-AS and BDNF. Besides, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Hoechst33342 staining were utilized to analyze the cell viability and apoptosis, respectively, Western blotting to evaluate the protein expressions, immunofluorescence to assess the Cytochrome C (Cyt C) release, and Rhodamine 123 (Rh123) to measure the mitochondrial membrane potential (MMP).The evaluation of oxidative stress was conducted via the determination of the levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT).

RESULTS

Aβ_25-35 apparently increased BDNF-AS but decreased BDNF in PC12 cells, which also reduced viability and induced apoptosis of PC12 cells. Silencing of BDNF-AS could significantly up-regulate BDNF in Aβ_25-35-induced PC12 cells, with the elevated cell viability. Moreover, silencing BDNF-AS inhibited the apoptosis of Aβ_25-35-induced PC12 cells, suppressed the release of Cyt C, reduced the expression of cleaved caspase-3 and Bax, and lowered the mean fluorescence intensity (MFI) of Rh123, but it elevated the expression of Bcl-2. Besides, silencing BDNF-AS also reduced ROS intensity and MDA content, but enhanced the activities of SOD and CAT.

CONCLUSION

Silencing BDNF-AS exerts protective functions to increase the viability, inhibit the apoptosis and oxidative stress of Aβ_25-35-induced PC12 cells by negative regulation of BDNF.

ABBREVIATIONS

Aβ_25-35: amyloid beta peptide 25-35; AD: Alzheimer's disease; LncRNA BDNF-AS: long non-coding RNA brain-derived neurotrophic factor anti-sense; OS: Oxidative stress.

Repetitive transcranial magnetic stimulation improves cognitive function of Alzheimer's disease patients

Repetitive transcranial magnetic stimulation (rTMS) acts as a kind of widely-applied and non-invasive method in the intervention of some neurological disorders. This prospective, randomized, double-blind, placebo-controlled trial investigates the effect of rTMS on 30 cases of Alzheimer’s disease (AD) participants, who were classified into mild and moderate groups. Neuropsychological tests were carried out using the AD Assessment Scale-cognitive subscale (ADAS-cog), Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), and World Health Organization University of California-Los Angeles, Auditory Verbal Learning Test (WHO-UCLA AVLT) before, immediately after, and 6 weeks after the intervention. In this work, data from 30 AD patients revealed that there was no obvious interaction effect of time-by-group. The ADAS-cog, MMSE and WHO-UCLA AVLT score in the rTMS group was significantly improved compared with baselines at 6 weeks after treatment (all p<0.05). Meanwhile, MoCA scores were also obviously ameliorated in the mild AD patients with rTMS. Besides, subgroup analysis showed that the effect of rTMS on the memory and language of mild AD patients was superior to those of moderate AD patients. In conclusion, our findings suggested that repetitive transcranial magnetic stimulation improves cognitive function, memory and language level of AD patients, especially in the mild stage of AD. Thus, rTMS can be recommended as a promising adjuvant therapy combined with cholinesterase inhibitors at the mild stage of AD patients.

Lychee seed extract protects against neuronal injury and improves cognitive function in rats with type II diabetes mellitus with cognitive impairment

Lychee seed is a traditional Chinese medicine and has many beneficial effects such as modulation of blood sugar and lipids, antioxidation, antivirus and antitumor. Studies have indicated that type II diabetes mellitus (T2DM) and Alzheimer's disease (AD) share common biological mechanisms including insulin resistance, impaired glucose metabolism, β-amyloid (Aβ) formation, oxidative stress and presence of advanced glycation end products (AGEs). The present study investigated the effects of lychee seed extract (LSE) on neuroprotection, cognitive function improvement and possible underlying mechanisms in a rat model of T2DM with cognitive impairment. We analyzed the chemical profile of LSE using a UHPLC-SPD chromatogram and evaluated its effect on the improvement of spatial learning and memory of rats by a Morris water maze. The levels of glucose, insulin, Aβ, AGEs, Tau protein and acetylcholinesterase in the blood and/or hippocampus of rats were determined by blood-glucose meter, radioimmunoassay, chemical chromatometry, enzyme-linked immunosorbent assay (ELISA) and immunohistochemical analysis, respectively. Results demonstrated that LSE consists of eight major and around 20 minor ingredients, and it remarkably prevents neuronal injury and improves cognitive functions in T2DM rats. The levels of glucose, insulin, Aβ, AGEs and Tau protein were significantly increased in the blood and/or hippocampus of T2DM rats, while LSE remarkably decreased their levels compared to vehicle treatment (P<0.01). The possible mechanisms may be associated with IR improvement and decreased formations of Aβ, AGEs and Tau protein in the hippocampus of T2DM rats. LSE may be developed as the agent for the treatment of T2DM and/or AD clinically.

Effects of donepezil on liver and kidney functions for the treatment of Alzheimer's disease

Aim of the present study is to investigate the effects of medication with donepezil (acetylcholinesterase inhibitor) on the liver and kidney function in Alzheimer's disease (AD) and to compare the effects of donepezil medication during short (one month) and long term (six years) follow-ups. We evaluated female and male patients from Cukurova [42 AD patients; short term (5 mg/day)] and Dokuz Eylul [68 AD patients; long term (10 mg/day)] University Hospital. The results compared with the geriatric population without dementia in other words who are not in medication with donepezil. For short term evaluation all subjects underwent periodic examination with tests regarding hepatic and renal functions; firstly, before starting treatment and then repeated one month later. For long term evaluation all subjects underwent periodic examination with tests regarding hepatic and renal functions; three times at the end of each two consecutive years of treatment with donepezil. AD patients' results were also compared with 79 neurologically healthy geriatric patients without dementia who were over 65 years of age and were not receiving medication with donepezil. For this task, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels are used to predict possible liver damage, while the blood urea nitrogen (BUN) and creatinine (CRE) levels for kidney damage. No significant difference between the groups regarding the routine control of biochemical parameters was observed in short term drug medication. In long term patients' group; the effects of two years use of donepezil on renal and hepatic function were also evaluated and levels of AST, ALT, BUN and CRE were found to be increased significantly compared to pretreatment levels. But, they remained in the reference intervals. However, levels of AST and ALT at the end of the fourth year of therapy were similar to those measured at the end of the second year, levels of BUN and CRE continuing to increase with staying below the reference limits. Functional markers obtained at the end of the sixth year of therapy were not differing from those of the fourth year. No significant difference was found during comparisons within the results of the neurologically healthy geriatric patient group. During comparisons between the two groups, measurements obtained at all-time points were significantly high in donepezil treated AD patients. We concluded that customized dosage according to hepatic and renal functions is necessary for using acetylcholinesterase inhibitor in AD patients.

Evaluation of Novel Dual Acetyl- and Butyrylcholinesterase Inhibitors as Potential Anti-Alzheimer's Disease Agents Using Pharmacophore, 3D-QSAR, and Molecular Docking Approaches

DL0410, containing biphenyl and piperidine skeletons, was identified as an acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitor through high-throughput screening assays, and further studies affirmed its efficacy and safety for Alzheimer’s disease treatment. In our study, a series of novel DL0410 derivatives were evaluated for inhibitory activities towards AChE and BuChE. Among these derivatives, compounds 6-1 and 7-6 showed stronger AChE and BuChE inhibitory activities than DL0410. Then, pharmacophore modeling and three-dimensional quantitative structure activity relationship (3D-QSAR) models were performed. The R² of AChE and BuChE 3D-QSAR models for training set were found to be 0.925 and 0.883, while that of the test set were 0.850 and 0.881, respectively. Next, molecular docking methods were utilized to explore the putative binding modes. Compounds 6-1 and 7-6 could interact with the amino acid residues in the catalytic anionic site (CAS) and peripheral anionic site (PAS) of AChE/BuChE, which was similar with DL0410. Kinetics studies also suggested that the three compounds were all mixed-types of inhibitors. In addition, compound 6-1 showed better absorption and blood brain barrier permeability. These studies provide better insight into the inhibitory behaviors of DL0410 derivatives, which is beneficial for rational design of AChE and BuChE inhibitors in the future.

Lychee Seed Saponins Improve Cognitive Function and Prevent Neuronal Injury via Inhibiting Neuronal Apoptosis in a Rat Model of Alzheimer's Disease

Lychee seed is a traditional Chinese medicine and possesses many activities, including hypoglycemia, liver protection, antioxidation, antivirus, and antitumor. However, its effect on neuroprotection is still unclear. The present study investigated the effects of lychee seed saponins (LSS) on neuroprotection and associated mechanisms. We established a rat model of Alzheimer’s disease (AD) by injecting Aβ_25–35 into the lateral ventricle of rats and evaluated the effect of LSS on spatial learning and memory ability via the Morris water maze. Neuronal apoptosis was analyzed by hematoxylin and eosin stain and terminal deoxynucleotidyl transferase (Tdt)-mediated dUTP nick-end labeling analysis, and mRNA expression of caspase-3 and protein expressions of Bax and Bcl-2 by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. The results showed that LSS remarkably improved cognitive function and alleviated neuronal injury by inhibiting apoptosis in the hippocampus of AD rats. Furthermore, the mRNA expression of caspase-3 and the protein expression of Bax were downregulated, while the protein expression of Bcl-2 and the ratio of Bcl-2/Bax were increased by LSS. We demonstrate that LSS significantly improves cognitive function and prevent neuronal injury in the AD rats via regulation of the apoptosis pathway. Therefore, LSS may be developed as a nutritional supplement and sold as a drug for AD prevention and/or treatment.

Synthesis and biological evaluation of ranitidine analogs as multiple-target-directed cognitive enhancers for the treatment of Alzheimer's disease

Using molecular modeling and rationally designed structural modifications, the multi-target structure-activity relationship for a series of ranitidine analogs has been investigated. Incorporation of a variety of isosteric groups indicated that appropriate aromatic moieties provide optimal interactions with the hydrophobic and π-π interactions with the peripheral anionic site of the AChE active site. The SAR of a series of cyclic imides demonstrated that AChE inhibition is increased by additional aromatic rings, where 1,8-naphthalimide derivatives were the most potent analogs and other key determinants were revealed. In addition to improving AChE activity and chemical stability, structural modifications allowed determination of binding affinities and selectivities for M1-M4 receptors and butyrylcholinesterase (BuChE). These results as a whole indicate that the 4-nitropyridazine moiety of the JWS-USC-75IX parent ranitidine compound (JWS) can be replaced with other chemotypes while retaining effective AChE inhibition. These studies allowed investigation into multitargeted binding to key receptors and warrant further investigation into 1,8-naphthalimide ranitidine derivatives for the treatment of Alzheimer's disease.