Berberine Alleviates Amyloid-Beta Pathology in the Brain of APP/PS1 Transgenic Mice via Inhibiting β/γ-Secretases Activity and Enhancing α-Secretases

Therapeutic Effects of the major alkaloid constituents of Evodia rutaecarpa in Alzheimer's disease

Since the report of Alzheimer's disease (AD) in 1907, it has garnered widespread attention due to its intricate pathogenic mechanisms, significant impact on patients' lives, and the substantial burden it places on society. Presently, effective treatments for AD remain elusive. Recent pharmacological studies on the traditional East Asian herb, Evodia rutaecarpa, have revealed that the bioactive alkaloid components within it can ameliorate AD-related cognitive impairments and neurological damage through various pathways, including anti-inflammatory, antioxidant, and anti-acetylcholinesterase activities. Consequently, this article provides an overview of the pharmacological effects and research status of the four main alkaloid components found in Evodia concerning AD. We hope this article will serve as a valuable reference for experimental and clinical research on the use of Evodia in AD prevention and treatment.

Curcumin-derived carbon quantum dots: Dual actions in mitigating tau hyperphosphorylation and amyloid beta aggregation

The amyloid cascade and tau hypotheses both hold significant implications for the pathogenesis of Alzheimer's disease (AD). Curcumin shows potential by inhibiting the aggregation of amyloid beta (Aβ) and reducing tau hyperphosphorylation, however, its use is limited due to issues with solubility and bioavailability. Carbon dots, recognized for their high biocompatibility and optimal water solubility, have demonstrated the capability to inhibit either Aβ or tau aggregation. Nonetheless, their effects on tau hyperphosphorylation are yet to be extensively explored. This study aims to evaluate the water-soluble curcumin-derived carbon quantum dots (Cur-CQDs) synthesized via an eco-friendly method, designed to preserve the beneficial effects of curcumin while overcoming solubility challenges. The synthesis of Cur-CQDs involves a single-step dry heating process using curcumin, resulting in dots that exhibit negligible cytotoxicity to SH-SY5Y cells at the examined concentrations. Notably, Cur-CQDs have shown the ability to simultaneously mitigate Aβ aggregation and tau hyperphosphorylation. Therefore, it is suggested that Cur-CQDs may hold potential for AD treatment, a hypothesis deserving of further research.

Effect of berberine on cognitive function and β-amyloid precursor protein in Alzheimer's disease models: a systematic review and meta-analysis

Introduction: Berberine is an isoquinoline alkaloid extracted from Berberis vulgaris, which possesses a variety of pharmacological activities. Alzheimer's disease (AD) is a complex disease with multiple pathologic factors, with cognitive decline being the main manifestation of AD. The neuroprotective effects of berberine in animal models of Alzheimer's disease (AD) have been widely reported, exhibiting protective effects against risk factors associated with AD. In this study, we summarize and evaluate the effects of berberine on cognitive function and β-amyloid precursor protein in animal models of AD. Material and methods: Eligible studies were retrieved from PubMed, MEDLINE, EMBASE, Web of Science, and Cochrane Library databases up to 1 June 2023. Risk of bias was assessed by the Systematic Review Center for Laboratory Animal Experiments (SYRCLE). Statistical analyses were performed using STATA 14.0 and Review Manger 5.4 software to calculate weighted standardized mean difference (SMD) and 95% confidence intervals (CI), Morris water maze (MWM) test and β-amyloid precursor protein as outcome measures. Heterogeneity was tested using the I2 test. Sensitivity analysis and publication bias were also assessed. Results: 19 studies involving 360 animals met the inclusion criteria, and the results of the meta-analysis showed that berberine decreased escape latency (SMD = -2.19, 95% CI: (-2.50, -1.88), p < 0.00001), increased the number of platform crossings (SMD = 4.27, 95% CI (3.38, 5.17), p < 0.00001), time in the target quadrant (SMD = 5.92, 95% CI (4.43, 7.41), p < 0.00001) and APP expression (SMD = 0.73, 95% CI: (0.25, 1.21), p = 0.003). Conclusion: Berberine can regulate APP expression and improve cognitive function in animal models of AD, and the mechanism may be related to the involvement of berberine in APP processing and influence the expression of its related factors. Systematic review registration: PROSPERO, CRD42023437445.

Neuroprotective effects and possible mechanisms of berberine in animal models of Alzheimer's disease: a systematic review and meta-analysis

Background: Recently, multiple preclinical studies have reported the beneficial effect of berberine in the treatment of Alzheimer's disease (AD). Nevertheless, the neuroprotective effects and possible mechanisms of berberine against AD are not universally recognized. This study aimed to conduct a systematic review and meta-analysis by integrating relevant animal studies to assess the neuroprotective effects and potential mechanisms of berberine on AD. Methods: We systematically searched PubMed, Embase, Scopus and Web of Science databases that reported the effects of berberine on AD models up to 1 February 2023. The escape latency, times of crossing platform, time spent in the target quadrant and pro-oligomerized amyloid beta 42 (Aβ1-42) were included as primary outcomes. The secondary outcomes were the Tau-ps 204, Tau-ps 404, β-site of APP cleaving enzyme (BACE1), amyloid precursor protein (APP), acetylcholine esterase (AChE), tumor necrosis factor ⍺ (TNF-α), interleukin 1β (IL-1β), IL-6, nitric oxide (NO), glial fibrillary acidic protein (GFAP), malonaldehyde (MDA), glutathione S-transferase (GST), glutathione (GSH), glutathione peroxidase (GPx), Beclin-1 and neuronal apoptosis cells. This meta-analysis was conducted using RevMan 5.4 and STATA 15.1. The SYRCLE's risk of bias tool was used to assess the methodological quality. Results: Twenty-two studies and 453 animals were included in the analysis. The overall results showed that berberine significantly shortened the escape latency (p < 0.00001), increased times of crossing platform (p < 0.00001) and time spent in the target quadrant (p < 0.00001), decreased Aβ1-42 deposition (p < 0.00001), Tau-ps 202 (p < 0.00001) and Tau-ps 404 (p = 0.002), and improved BACE1, APP, AChE, Beclin-1, neuronal apoptosis cells, oxidative stress and inflammation levels. Conclusion: Berberine may be a promising drug for the treatment of AD based on preclinical evidence (especially when the dose was 5-260 mg/kg). The potential mechanisms for these protective effects may be closely related to anti-neuroinflammation, anti-oxidative stress, modulation of autophagy, inhibition of neuronal apoptosis and protection of cholinergic system. However, these results may be limited by the quality of existing research. Larger and methodologically more rigorous preclinical research are needed to provide more convincing evidence.

Therapeutic potential of natural products against Alzheimer's disease via autophagic removal of Aβ

The pathological features of Alzheimer's disease (AD), a progressive neurodegenerative disorder, include the deposition of extracellular amyloid beta (Aβ) plaques and intracellular tau neurofibrillary tangles. A decline in cognitive ability is related to the accumulation of Aβ in patients with AD. Autophagy, which is a primary intracellular mechanism for degrading aggregated proteins and damaged organelles, plays a crucial role in AD. In this review, we summarize the most recent research progress regarding the process of autophagy and the effect of autophagy on Aβ. We further discuss some typical monomers of natural products that contribute to the clearance of Aβ by autophagy, which can alleviate AD. This provides a new perspective for the application of autophagy modulation in natural product therapy for AD.

Bioassays guided isolation of berberine from Berberis lycium and its neuroprotective role in aluminium chloride induced rat model of Alzheimer's disease combined with insilico molecular docking

OBJECTIVE

Berberis lycium is an indigenous plant of Pakistan that is known for its medicinal properties. In the current study, we investigated the anti-Alzheimer's effect of berberine isolated from Berberis lycium.

METHODS

Root extract of B. lycium was subjected to acetylcholinesterase inhibition assay and column chromatography for bioassays guided isolation of a compound. The neuroprotective and memory improving effects of isolated compound were evaluated by aluminium chloride induced Alzheimer's disease rat model, elevated plus maze (EPM) and Morris water maze (MWM) tests., Levels of dopamine and serotonin in rats brains were determined using HPLC. Moreover, western blot and docking were performed to determine interaction between berberine and β-secretase.

RESULTS

During fractionation, ethyl acetate and methanol (3:7) fraction was collected from solvent mixture of ethyl acetate and methanol. This fraction showed the highest anti-acetylcholinesterase activity and was alkaloid positive. The results of TLC and HPLC analysis indicated the presence of the isolated compound as berberine. Additionally, the confirmation of isolated compound as berberine was carried out using FTIR and NMR analysis. In vivo EPM and MWM tests showed improved memory patterns after berberine treatment in Alzheimer's disease model. The levels of dopamine, serotonin and activity of antioxidant enzymes were significantly (p<0.05) enhanced in brain tissue homogenates of berberine treated group. This was supported by decreased expression of β-secretase in berberine treated rat brain homogenates and good binding affinity of berberine with β-secretase in docking studies. Binding energies for interaction of β-secretase with berberine and drug Rivastigmine is -7.0 kcal/mol and -5.8 kcal/mol respectively representing the strong interactions. The results of docked complex of secretase with berberine and Rivastigmine was carried out using Gromacs which showed significant stability of complex in terms of RMSD and radius of gyration. Overall, the study presents berberine as a potential drug against Alzheimer's disease by providing evidence of its effects in improving memory, neurotransmitter levels and reducing β-secretase expression in the Alzheimer's disease model.

Protective effects of berberine against β-amyloid-induced neurotoxicity in HT22 cells via the Nrf2/HO-1 pathway

Neuronal apoptosis has been found to have a pivotal role in the course of Alzheimer's disease (AD). Berberine (BBR), a potent antioxidant, occurs in plants such as Berberis, Phellodendron chinense, and Hydrastis canadensis. In this study, a neuronal apoptotic model was established in vitro using HT22 cells induced by Aβ_25-35 to explore whether BBR contributes to protecting neurons against Aβ_25-35-induced neurotoxicity, as well as its potential mechanisms. BBR was applied to HT22 cells for 1 h prior to exposing the cells to Aβ_25-35 for 24 h. A CCK-8 assay was utilized to assess cell viability, and Annexin V - fluorescein isothiocyanate (FITC)/propidium iodide and Hoechst 33342 fluorescence staining were used to measure the rate of cell apoptosis. Existing scientific literature was also reviewed to further determine the effects of BBR on ROS production and mitochondrial function in HT22 cells. Furthermore, the expressions of proteins, including cytochrome C, cleaved caspase-3, p-p65, p65, and Nrf2/HO-1 antioxidant axis were assessed by Western blotting. The data indicated that BBR markedly improved cell viability, inhibited apoptosis and intracellular ROS levels, improved mitochondrial membrane potentials, decreased the rate of p-p65/p65, cytochrome C, and cleaved caspase-3, and intensified the activity of Nrf2/HO-1 antioxidants in HT22 cells. Overall, the findings indicated that BBR provides a certain level of neuroprotectiveness in HT22 cells exposed to Aβ_25-35 via relieving oxidative stress, as well as by restraining the mitochondrial pathway of cellular apoptosis. In addition, the restraint of NF-κB activity and sensitization of the Nrf2/HO-1 antioxidant axis, which together are intimately involved in the neuroprotection of BBR, may be possible mechanisms accounting for its effectiveness against Aβ_25-35in vitro.

Berberine Rescues D-Ribose-Induced Alzheimer's Pathology via Promoting Mitophagy

Mitochondrial dysfunction is considered an early event of Alzheimer disease (AD). D-ribose is a natural monosaccharide that exists in cells, especially in mitochondria, and can lead to cognitive dysfunction. However, the reason for this is unclear. Berberine (BBR) is an isoquinoline alkaloid that can target mitochondria and has great prospect in the treatment of AD. The methylation of PINK1 reinforces the burden of Alzheimer's pathology. This study explores the role of BBR and D-ribose in the mitophagy and cognitive function of AD related to DNA methylation. APP/PS1 mice and N2a cells were treated with D-ribose, BBR, and mitophagy inhibitor Mdivi-1 to observe their effects on mitochondrial morphology, mitophagy, neuron histology, AD pathology, animal behavior, and PINK1 methylation. The results showed that D-ribose induced mitochondrial dysfunction, mitophagy damage, and cognitive impairment. However, BBR inhibition of PINK1 promoter methylation can reverse the above effects caused by D-ribose, improve mitochondrial function, and restore mitophagy through the PINK1-Parkin pathway, thus reducing cognitive deficits and the burden of AD pathology. This experiment puts a new light on the mechanism of action of D-ribose in cognitive impairment and reveals new insights in the use of BBR for AD treatment.

Therapeutic potential of ADAM10 modulation in Alzheimer's disease: a review of the current evidence

Alzheimer's disease (AD), the most common neurodegenerative disease worldwide, is caused by loss of neurons and synapses in central nervous system. Several causes for neuronal death in AD have been introduced, the most important of which are extracellular amyloid β (Aβ) accumulation and aggregated tau proteins. Increasing evidence suggest that targeting the process of Aβ production to reduce its deposition can serve as a therapeutic option for AD management. In this regard, therapeutic interventions shown that a disintegrin and metalloproteinase domain-containing protein (ADAM) 10, involved in non-amyloidogenic pathway of amyloid precursor protein processing, is known to be a suitable candidate. Therefore, this review aims to examine the molecular properties of ADAM10, its role in AD, and introduce it as a therapeutic target to reduce the progression of the disease. Video abstract.

The efficacy and mechanism of berberine in improving aging-related cognitive dysfunction: A study based on network pharmacology

Objective

To analyze the effects and mechanisms of berberine in the treatment of aging-related cognitive dysfunction based on network pharmacology methods, molecular docking techniques, and animal experiments.

Methods

A mouse model of cognitive dysfunction was constructed by subcutaneous injection of D-galactose (D-gal) for 10 weeks, and the neuroprotective effects of berberine on aging-related cognitive dysfunction mice were evaluated by the Morris water maze (MWM) and immunofluorescence staining. The targets of berberine were obtained by SwissTargetPrediction, GeneCards, and PharmMapper. Putative targets of cognitive dysfunction were obtained by GeneCards, TTD, and DrugBank database. The STRING database and Cytoscape software were applied for protein-protein interaction (PPI) analysis and further screening of core targets. The DAVID database was used for Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) enrichment analysis to clarify the biological processes and pathways involved in the intersection targets, and AutoDockTools was adopted for molecular docking verification of core targets. Finally, the core genes were validated using real-time quantitative PCR.

Results

The MWM results showed that treatment with berberine significantly improved spatial learning and memory in mice with cognitive decline induced by D-gal. Immunofluorescence staining indicated that berberine modified the levels of aging-related markers in the brain. A total of 386 berberine putative targets associated with cognitive dysfunction were identified based on the public database. The core targets of berberine for improving cognitive function, include Mapk1, Src, Ctnnb1, Akt1, Pik3ca, Tp53, Jun, and Hsp90aa1. GO enrichment and KEGG pathway enrichment analyses indicated that the mechanism of berberine in the treatment of aging-related cognitive dysfunction is attributed to pathways such as PI3K-AKT and MAPK pathways. In vivo experiments further confirmed that Akt1, Ctnnb1, Tp53, and Jun were involved in the neuroprotective actions of berberine.

Conclusion

This study reveals the multi-target and multi-pathway effects of berberine on regulating aging-related cognitive dysfunction, which provides preclinical evidence and may promote new drug development in mitigating cognitive dysfunction.

Carrier-free Chinese herbal small molecules self-assembly with 3D-porous crystal framework as a synergistic anti-AD agent

Alzheimer's disease (AD) is a devastating neurodegenerative disease caused by multiple factors. Single-target drugs have limited efficacy for AD treatment. Therefore, multi-target intervention strategy has great potential. Traditional Chinese medicine (TCM) is mostly used in the form of compound prescription, which has the polypharmacology behavior. Rhizoma Coptidis and Radix et Rhizoma Rhei are frequently used as the couplet medicines of TCM for AD therapy. In this study, the novel carrier-free nanoassembly with 3D-porous frame crystal structure has formulated from supramolecular self-assembly of berberine (BER) and rhein (RHE), the main active components of Rhizoma Coptidis and Radix et Rhizoma Rhei, respectively. Combining with the spectral data and single crystal structure, the self-assembly process was clarified as dominated by electrostatic interaction and π-π stacking. In vitro release property, cholinesterase (ChE) inhibition, β-amyloid (Aβ) aggregation regulation, radical elimination, metal ions chelation and cytotoxicity assay indicated that the obtained BER-RHE assembly had the Fickian diffusion-controlled sustained release ability, synergistic biological activities and virtually no neurotoxicity. In addition, in vivo reactive oxygen species (ROS) level evaluation showed that the assembly could reduce the accumulation of intracellular ROS in Caenorhabditis elegans (C. elegans). Meanwhile, BER-RHE assembly could also be used as a novel potential carrier for drug delivery due to its superior 3D-porous frame. This green and facile strategy for carrier-free nanoassembly microscopic construction via supramolecular self-assembly might provide inspiration for the development of multi-target therapy for AD and the design of the novel drug delivery system.

Berberine Ameliorates Cognitive Disorder via GSK3β/PGC-1α Signaling in APP/PS1 Mice

Previous studies have revealed that Berberine (BBR) had therapeutic effects on Alzheimer's disease (AD). However, the underlying mechanism of BBR in the treatment of AD is unclear. The study was to investigate whether berberine ameliorates cognitive disorder in AD by regulating on GSK3β/PGC-1α signaling pathway. APP/PS1 mice were treated with BBR (50 mg/kg and 100 mg/kg) for 4 mo, and the cognitive function of mice was tested by Morris water maze. The levels of inflammatory cytokines IL-1β, TNF-α, and IL-6 in hippocampus of mice were detected by ELISA kits. The damage of neuronal in hippocampal CA1 was detected by Nissl staining. The tau and GSK3β protein were detected by western blot. The results showed that BBR treatment obviously improved spatial cognitive function of APP/PS1 mice. Meanwhile, the pro-inflammatory cytokines were decreased in hippocampus by the administration of BBR. Additionally, BBR significantly alleviated neuronal damage and reduced the levels of hyperphosphorylated tau at sites of Thr205 and Thr231 in hippocampus. Importantly, BBR inhibited the activity of GSK3β and increased the expression of PGC-1α. Consequently, our results demonstrates that BBR could improve the cognitive function by inhibiting the tau hyperphosphorylation and neuroinflammation. These beneficial effects of BBR may be attributed to the regulation of GSK3β/PGC-1α signaling pathway in APP/PS1 mice. These findings reveal a vital role for GSK3β/PGC-1α signaling pathway in retarding cognitive disorder, indicating that PGC-1α might be a potential target for the treatment of AD.

Network Pharmacology-Based Strategy to Investigate the Pharmacologic Mechanisms of Coptidis Rhizoma for the Treatment of Alzheimer's Disease

Background

Alzheimer's disease (AD) is becoming a more prevalent public health issue in today's culture. The experimental study of Coptidis Rhizoma (CR) and its chemical components in AD treatment has been widely reported, but the principle of multi-level and multi-mechanism treatment of AD urgently needs to be clarified.

Objective

This study focuses on network pharmacology to clarify the mechanism of CR's multi-target impact on Alzheimer's disease.

Methods

The Phytochemical-compounds of CR have been accessed from the Traditional Chinese Medicine Database and Analysis Platform (TCMSP) and Symmap database or HPLC determination. The values of Oral Bioavailability (OB) ≥ 30% and Drug Like (DL) ≥ 0.18 or blood ingredient were used to screen the active components of CR; the interactive network of targets and compounds were constructed by STRING and Cytoscape platform, and the network was analyzed by Molecular Complex Detection (MCODE); Gene Ontology (GO) function, Kyoto Encyclopedia of Genes and Genomes Pathway (KEGG) and metabolic pathway enrichment of targets were carried out with Metascape, the Database for Annotation, Visualization and Integrated Discovery (DAVID) and MetaboAnalyst platform; Based on CytoHubba, the potential efficient targets were screened by Maximal Clique Centrality (MCC) and Degree, the correlation between potential efficient targets and amyloid β-protein (Aβ), Tau pathology was analyzed by Alzdata database, and the genes related to aging were analyzed by Aging Altas database, and finally, the core targets were obtained; the binding ability between ingredients and core targets evaluated by molecular docking, and the clinical significance of core targets was assessed with Gene Expression Omnibus (GEO) database.

Results

19 active components correspond to 267 therapeutic targets for AD, of which 69 is potentially effective; in module analysis, RELA, TRAF2, STAT3, and so on are the critical targets of each module; among the six core targets, RELA, MAPK8, STAT3, and TGFB1 have clinical therapeutic significance; GO function, including 3050 biological processes (BP), 257 molecular functions (MF), 184 cellular components (CC), whose functions are mainly related to antioxidation, regulation of apoptosis and cell composition; the HIF-1 signaling pathway, glutathione metabolism is the most significant result of 134 KEGG signal pathways and four metabolic pathways, respectively; most of the active components have an excellent affinity in docking with critical targets.

Conclusion

The pharmacological target prediction of CR based on molecular network pharmacology paves the way for a multi-level networking strategy. The study of CR in AD treatment shows a bright prospect for curing neurodegenerative diseases.

Effect of Berberine Hydrochloride on the Diversity of Intestinal Flora in Parkinson's Disease Patients

This study aimed to investigate the effect of berberine hydrochloride on the diversity of intestinal flora in patients with Parkinson's disease (PD). Prospectively selected 68 PD patients, admitted to our hospital from April 2021 to June 2021, were randomly assigned to an observation group and a control group (n = 34 per group). Patients in the control group were given conventional treatment in accordance with Parkinson's diagnosis and treatment guidelines. Patients in the observation group were administered berberine hydrochloride besides the treatment in the control group. After continuous treatment for 3 months, the enzyme-linked immunosorbent assay was applied to determine interleukin-8 (IL-8), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) levels. High-throughput sequencing technology was employed to perform DNA sequencing on the 16S rRNA genes of all bacteria in stool samples before and after treatment in the two groups to analyze the distribution of intestinal flora. After treatment, the levels of IL-8, IL-6, and TNF-α were lower in the observation group than those in the control group (P < 0.05). Regarding intestinal flora, the Chao index, Ace index, and Shannon index were higher in the observation group than those in the control group. The Simpson index was lower in the observation group than that of the control group (P < 0.05). The principal component analysis chart analysis exhibited that the overall structure of the intestinal flora was quite different between the observation and the control groups after treatment. Berberine hydrochloride can improve the disorder of intestinal flora in PD patients and suppress the expression of inflammatory factors.

Recent Advances Towards Diagnosis and Therapeutic Fingerprinting for Alzheimer's Disease

Since the report of "a peculiar severe disease process of the cerebral cortex" by Alois Alzheimer in 1906, it was considered to be a rare condition characterized by loss of cognition, memory impairment, and pathological markers such as senile plaques or neurofibrillary tangles (NFTs). Later on, the report was published in the textbook "Psychiatrie" and the disease was named as Alzheimer's disease (AD) and was known to be the consequences of aging; however, owing to its complex etiology, there is no cure for the progressive neurodegenerative disorder. Our current understanding of the mechanisms involved in the pathogenesis of AD is still at the mechanistic level. The treatment strategies applied currently only alleviate the symptoms and co-morbidities. For instance, the available treatments such as the usage of acetylcholinesterase inhibitors and N-methyl D-aspartate antagonists have minimal impact on the disease progression and target the later aspects of the disease. The recent advancements in the last two decades have made us more clearly understand the pathophysiology of the disease which has led to the development of novel therapeutic strategies. This review gives a brief idea about the various facets of AD pathophysiology and its management through modern investigational therapies to give a new direction for development of targeted therapeutic measures.

Therapeutic Efficacies of Berberine against Neurological Disorders: An Update of Pharmacological Effects and Mechanisms

Neurological disorders are ranked as the leading cause of disability and the second leading cause of death worldwide, underscoring an urgent necessity to develop novel pharmacotherapies. Berberine (BBR) is a well-known phytochemical isolated from a number of medicinal herbs. BBR has attracted much interest for its broad range of pharmacological actions in treating and/or managing neurological disorders. The discoveries in basic and clinical studies of the effects of BBR on neurological disorders in the last decade have provided novel evidence to support the potential therapeutical efficacies of BBR in treating neurological diseases. In this review, we summarized the pharmacological properties and therapeutic applications of BBR against neurological disorders in the last decade. We also emphasized the major pathways modulated by BBR, which provides firm evidence for BBR as a promising drug candidate for neurological disorders.

Neuroprotective role of apocynin against pentylenetetrazole kindling epilepsy and associated comorbidities in mice by suppression of ROS/RNS

Epilepsy is a neurological disease that transpires due to the unusual synchronized neuronal discharge within the central nervous system, which drives repetitious unprovoked seizures. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is a complex enzyme accountable for reactive oxygen species (ROS) production, neurodegeneration, neurotoxicity, memory impairment, vitiates normal cellular processes, long term potentiation, and thus, implicated in the pathogenesis of epilepsy. Therefore, the present study was sketched to examine the neuroprotective effect of apocynin, NADPH oxidase inhibitor in pentylenetetrazole kindling epilepsy, and induced comorbidities in mice. Mice (either sex) were given pentylenetetrazole (35 mg/kg, i.p.) every other day up to 29 days, and a challenge test was executed on the 33^rd day. Pretreatment with apocynin (25, 50, and 100 mg/kg, i.p.) was carried out from 1^st to 33^rd day. Rotarod and open field test were performed on the 1^st, 10^th, 20^th, and 30^th days of the study. Animals were tutored on the morris water maze from 30^th to 33^rd day, and the retention was registered on the 34^th day. Tail suspension test and elevated plus maze were sequentially performed on the 32^nd and 33^rd day of the study. On the 34^th day, animals were sacrificed, and their brains were isolated to conduct biochemical estimation. NADPH oxidase activation due to chronic pentylenetetrazole treatment resulted in generalized tonic-clonic seizures, enhanced oxidative stress, remodeled neurotransmitters' level, and resulted in comorbidities (anxiety, depression, and memory impairment). Pretreatment with apocynin significantly restricted the pentylenetetrazole induced seizure severity, ROS production, neurotransmitter alteration, and comorbid conditions by inhibiting the NADPH oxidase enzyme.

Dietary agents in mitigating chemotherapy-related cognitive impairment (chemobrain or chemofog): first review addressing the benefits, gaps, challenges and ways forward

Chemobrain or chemofog is one of the important but less investigated side effects, where the cancer survivors treated with chemotherapy develop long-term cognitive impairments, affecting their quality of life. The biological mechanisms triggering the development of chemobrain are largely unknown. However, a literature study suggests the generation of free radicals, oxidative stress, inflammatory cytokines, epigenetic chromatin remodeling, decreased neurogenesis, secretion of brain-derived neurotropic factor (BDNF), dendritic branching, and neurotransmitter release to be the cumulative contributions to the ailment. Unfortunately, there is no means to prevent/mitigate the development and intensity of chemobrain. Given the lack of effective prevention strategies or treatments, preclinical studies have been underway to ascertain the usefulness of natural products in mitigating chemobrain in the recent past. Natural products used in diets have been shown to provide beneficial effects by inhibition of free radicals, oxidative stress, inflammatory processes, and/or concomitant upregulation of various cell survival proteins. For the first time, this review focuses on the published effects of astaxanthin, omega-3 fatty acids, ginsenoside, cotinine, resveratrol, polydatin, catechin, rutin, naringin, curcumin, dehydrozingerone, berberine, C-phycocyanin, the higher fungi Cordyceps militaris, thyme (Thymus vulgaris) and polyherbal formulation Mulmina™ in mitigating cognitive impairments in preclinical models of study, and also addresses their potential neuro-therapeutic mechanisms and applications in preventing/ameliorating chemobrain.

Quercetin stimulates the non-amyloidogenic pathway via activation of ADAM10 and ADAM17 gene expression in aluminum chloride-induced Alzheimer's disease rat model

AIMS

Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder characterized by declined cognitive functions in the elderly. Quercetin (Q) is a potent flavonol that has neuroprotective effects on AD derangements. The present study aimed to evaluate the α-secretase stimulatory function of Q through activation of ADAM10 and ADAM17 gene expression in the aluminum chloride (AlCl3)-induced AD rat model.

MAIN METHODS

After induction of AD in rats by oral administration of AlCl3 (50 mg/kg) for 28 days, the Q doses (25 and 50 mg/kg) were orally administered for 28 days. Rats performed the behavioral assessments during the last week of the treatment period. Hippocampi were harvested for assessments of the neurochemical and histopathological examinations and gene expression analysis.

KEY FINDINGS

Administration of Q to AlCl₃-induced AD rat model attenuated behavioral deficits, improved cholinergic and dopaminergic dysfunctions, and diminished insoluble amyloid β (Aβ) plaques aggregation in the hippocampus. These ameliorative effects of Q were associated with down-regulation of APP, BACE1, APH1, and PSEN1 and up-regulation of ADAM10 and ADAM17 gene expression levels in the hippocampus.

SIGNIFICANCE

The present study suggests that Q might attenuate neurotransmission impairment, Aβ aggregation in the hippocampus, and behavioral deficits in the AlCl₃-induce AD rat model via up-regulating ADAM 10 and ADAM 17 (α-secretase) gene expression, leading to the inhibition of the amyloidogenic pathway. In support of the present finding, we suggest that ADAM10 and ADAM17 activation might be potential drug targets for AD to counteract the Aβ aggregation and cognitive deterioration.

Selective Secretase Targeting for Alzheimer's Disease Therapy

Alzheimer's disease (AD) is associated with marked atrophy of the cerebral cortex and accumulation of amyloid plaques and neurofibrillary tangles. Amyloid plaques are formed by oligomers of amyloid-β (Aβ) in the brain, with a length of 42 and 40 amino acids. α-secretase cleaves amyloid-β protein precursor (AβPP) producing the membrane-bound fragment CTFα and the soluble fragment sAβPPα with neuroprotective activity; β-secretase produces membrane-bound fragment CTFβ and a soluble fragment sAβPPβ. After α-secretase cleavage of AβPP, γ-secretase cleaves CTFα to produce the cytoplasmic fragment AICD and P3 in the non-amyloidogenic pathway. CTFβ is cleaved by γ-secretase producing AICD as well as Aβ in amyloidogenic pathways. In the last years, the study of natural products and synthetic compounds, such as α-secretase activity enhancers, β-secretase inhibitors (BACE-1), and γ-secretase activity modulators, have been the focus of pharmaceuticals and researchers. Drugs were improved regarding solubility, blood-brain barrier penetration, selectivity, and potency decreasing Aβ42. In this regard, BACE-1 inhibitors, such as Atabecestat, NB-360, Umibecestat, PF-06751979 Verubecestat, LY2886721, Lanabecestat, LY2811376 and Elenbecestat, were submitted to phase I-III clinical trials. However, inhibition of Aβ production did not recover cognitive functions or reverse disease progress. Novel strategies are being developed, aiming at a partial reduction of Aβ production, such as the development of γ-secretase modulators or α-secretase activity enhancers. Such therapeutic tools shall focus on slowing down or minimizing the progression of neuronal damage. Here, we summarize structures and activities of the latest compounds designed for AD treatment, with remarkable in vitro, in vivo, and clinical phase activities.

Berberine Reduces Aβ42 Deposition and Tau Hyperphosphorylation via Ameliorating Endoplasmic Reticulum Stress

Alzheimer’s disease (AD) is tightly related to endoplasmic reticulum stress (ER stress), which aggravates two dominant pathological manifestations of AD: senile plaques and neurofibrillary tangles. Berberine is widely applied in the clinical treatment of many diseases and is reported to have anti-AD effects. In the present study, berberine was shown to ameliorate ER stress and cognitive impairment in APP/PS1 mice. We found ER stress plays a role as a central hub for signal transduction, which was evidenced by the hyperactivation of glycogen synthase kinase 3β (GSK3β) to phosphorylate tau and the activation of PRKR-like endoplasmic reticulum kinase (PERK) subsequently to phosphorylate eukaryotic translation initiation factor-2 α (eIF2α). Also, eIF2α has regulated the expression of beta-site APP cleaving enzyme-1 (BACE1), which cleaves APP into pro-oligomerized amyloid beta 42 (Aβ₄₂), the main component of senile plaques, proven by using siRNA targeting at eIF2α. Mechanically, berberine can reduce GSK3β activity, contributing to the downregulation of tau phosphorylation. Berberine also suppressed Aβ₄₂ production via inhibiting the PERK/eIF2α/BACE1 signaling pathway. Taken together, these findings indicated that berberine had the potential to ameliorate two major pathological manifestations of AD mainly by suppressing ER stress. Our work provided knowledge on the pharmacological intervention of AD and the possible targets for future drug development.

Neuroprotective Natural Products for Alzheimer's Disease

Alzheimer's disease (AD) is the number one neurovegetative disease, but its treatment options are relatively few and ineffective. In efforts to discover new strategies for AD therapy, natural products have aroused interest in the research community and in the pharmaceutical industry for their neuroprotective activity, targeting different pathological mechanisms associated with AD. A wide variety of natural products from different origins have been evaluated preclinically and clinically for their neuroprotective mechanisms in preventing and attenuating the multifactorial pathologies of AD. This review mainly focuses on the possible neuroprotective mechanisms from natural products that may be beneficial in AD treatment and the natural product mixtures or extracts from different sources that have demonstrated neuroprotective activity in preclinical and/or clinical studies. It is believed that natural product mixtures or extracts containing multiple bioactive compounds that can work additively or synergistically to exhibit multiple neuroprotective mechanisms might be an effective approach in AD drug discovery.

Hippocampal Aromatase Knockdown Aggravates Ovariectomy-Induced Spatial Memory Impairment, Aβ Accumulation and Neural Plasticity Deficiency in Adult Female Mice

Ovarian estrogens (mainly 17β estradiol, E2) have been involved in the regulation of the structure of hippocampus, the center of spatial memory. In recent years, high levels of aromatase (AROM), the estrogen synthase, has been localized in hippocampus; and this hippocampus-derived E2 seems to be functional in synaptic plasticity and spatial memory as ovarian E2 does. However, the contribution of ovarian E2 and hippocampal E2 to spatial memory and neural plasticity remains unclear. In this study, AROM-specific RNA interference AAVs (shAROM) were constructed and injected into the hippocampus of control or ovariectomized (OVX) mice. Four weeks later the spatial learning and memory behavior was examined with Morris water maze, the expression of hippocampal Aβ related proteins, selected synaptic proteins and CA1 synapse density, actin polymerization related proteins and CA1 spine density were also examined. The results showed that while OVX and hippocampal shAROM contributed similarly to most of the parameters examined, shAROM induced more increase in BACE1 (amyloidogenic β-secretase), more decrease in neprilysin (Aβ remover) and Profilin-1 (actin polymerization inducer). More importantly, combined OVX and shAROM treatment displayed most significant impairment of spatial learning and memory as well as decrease in synaptic plasticity compared to OVX or shAROM alone. In conclusion, the above results clearly demonstrated the crucial role of hippocampal E2 in the regulation of the structure and function of hippocampus besides ovarian E2, indicating that hippocampal E2 content should also be taken into consideration during estrogenic replacement.

Natural Products Targeting Amyloid Beta in Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by severe brain damage and dementia. There are currently few therapeutics to treat this disease, and they can only temporarily alleviate some of the symptoms. The pathogenesis of AD is mainly preceded by accumulation of abnormal amyloid beta (Aβ) aggregates, which are toxic to neurons. Therefore, modulation of the formation of these abnormal aggregates is strongly suggested as the most effective approach to treat AD. In particular, numerous studies on natural products associated with AD, aiming to downregulate Aβ peptides and suppress the formation of abnormal Aβ aggregates, thus reducing neural cell death, are being conducted. Generation of Aβ peptides can be prevented by targeting the secretases involved in Aβ-peptide formation (secretase-dependent). Additionally, blocking the intra- and intermolecular interactions of Aβ peptides can induce conformational changes in abnormal Aβ aggregates, whereby the toxicity can be ameliorated (structure-dependent). In this review, AD-associated natural products which can reduce the accumulation of Aβ peptides via secretase- or structure-dependent pathways, and the current clinical trial states of these products are discussed.

Potential of Naturally Derived Alkaloids as Multi-Targeted Therapeutic Agents for Neurodegenerative Diseases

Alkaloids are a class of secondary metabolites that can be derived from plants, fungi and marine sponges. They are widely known as a continuous source of medicine for the management of chronic disease including cancer, diabetes and neurodegenerative diseases. For example, galanthamine and huperzine A are alkaloid derivatives currently being used for the symptomatic management of neurodegenerative disease. The etiology of neurodegenerative diseases is polygenic and multifactorial including but not limited to inflammation, oxidative stress and protein aggregation. Therefore, natural-product-based alkaloids with polypharmacology modulation properties are potentially useful for further drug development or, to a lesser extent, as nutraceuticals to manage neurodegeneration. This review aims to discuss and summarise recent developments in relation to naturally derived alkaloids for neurodegenerative diseases.

Ameliorating Ribosylation-Induced Amyloid-β Pathology by Berberine via Inhibiting mTOR/p70S6K Signaling

BACKGROUND

Berberine (BBR) plays a neuroprotective role in the pathogenesis of Alzheimer's disease (AD), inhibiting amyloid-β (Aβ) production and promoting Aβ clearance. Advanced glycation end products (AGEs) promote Aβ aggregation and tau hyperphosphorylation. The activation of mTOR signaling occurring at the early stage of AD has a prominent impact on the Aβ production. This work focused on whether BBR regulates the production and clearance of ribosylation-induced Aβ pathology via inhibiting mTOR signaling.

OBJECTIVE

To explore whether BBR ameliorates ribosylation-induced Aβ pathology in APP/PS1 mice.

METHODS

Western blot and immunofluorescence staining were used to detect the related proteins of the mammalian target of Rapamycin (mTOR) signaling pathway and autophagy, as well as the related kinases of Aβ generation and clearance. Tissue sections and Immunofluorescence staining were used to observe Aβ42 in APP/PS1 mice hippocampal. Morris water maze test was used to measure the spatial learning and memory of APP/PS1 mice.

RESULTS

BBR improves spatial learning and memory of APP/PS1 mice. BBR limits the activation of mTOR/p70S6K signaling pathway and enhances autophagy process. BBR reduces the activity of BACE1 and γ-secretase induced by D-ribose, and enhances Aβ-degrading enzymes and Neprilysin, and inhibits the expression of Aβ in APP/PS1 mice.

CONCLUSION

BBR ameliorates ribosylation-induced Aβ pathology via inhibiting mTOR/p70S6K signaling and improves spatial learning and memory of the APP/PS1 mice.

LongShengZhi Capsule Attenuates Alzheimer-Like Pathology in APP/PS1 Double Transgenic Mice by Reducing Neuronal Oxidative Stress and Inflammation

Alzheimer’s disease (AD) is the most common form of dementia in the elderly. It may be caused by oxidative stress, inflammation, and cerebrovascular dysfunctions in the brain. LongShengZhi Capsule (LSZ), a traditional Chinese medicine, has been approved by the China Food and Drug Administration for treatment of patients with cardiovascular/cerebrovascular disease. LSZ contains several neuroprotective ingredients, including Hirudo, Astmgali Radix, Carthami Flos (Honghua), Persicae Semen (Taoren), Acori Tatarinowii Rhizoma (Shichangpu), and Acanthopanax Senticosus (Ciwujia). In this study, we aimed to determine the effect of LSZ on the AD process. Double transgenic mice expressing the amyloid-β precursor protein and mutant human presenilin 1 (APP/PS1) to model AD were treated with LSZ for 7 months starting at 2 months of age. LSZ significantly improved the cognition of the mice without adverse effects, indicating its high degree of safety and efficacy after a long-term treatment. LSZ reduced AD biomarker Aβ plaque accumulation by inhibiting β-secretase and γ-secretase gene expression. LSZ also reduced p-Tau expression, cell death, and inflammation in the brain. Consistently, in vitro, LSZ ethanol extract enhanced neuronal viability by reducing L-glutamic acid-induced oxidative stress and inflammation in HT-22 cells. LSZ exerted antioxidative effects by enhancing superoxide dismutase and glutathione peroxidase expression, reduced Aβ accumulation by inhibiting β-secretase and γ-secretase mRNA expression, and decreased p-Tau level by inhibiting NF-κB-mediated inflammation. It also demonstrated neuroprotective effects by regulating the Fas cell surface death receptor/B-cell lymphoma 2/p53 pathway. Taken together, our study demonstrates the antioxidative stress, anti-inflammatory, and neuroprotective effects of LSZ in the AD-like pathological process and suggests it could be a potential medicine for AD treatment.

Berberine Administration in Treatment of Colitis: A Review

Berberine (Brb) is one of the well-known naturally occurring compounds exclusively found in Berberis vulgaris and other members of this family, such as Berberis aristata, Berberis aroatica, and Berberis aquifolium. This plant-derived natural compound has a variety of therapeutic impacts, including anti-oxidant, anti-inflammatory, anti-diabetic, and anti-tumor. Multiple studies have demonstrated that Brb has great anti-inflammatory activity and is capable of reducing the levels of proinflammatory cytokines, while it enhances the concentrations of anti-inflammatory cytokines, making it suitable for the treatment of inflammatory disorders. Colitis is an inflammatory bowel disease with chronic nature. Several factors are involved in the development of colitis and it appears that inflammation and oxidative stress are the most important ones. With respect to the anti-inflammatory and antioxidant effects of Brb, its administration seems to be beneficial in the treatment of colitis. In the present review, the protective effects of Brb in colitis treatment and its impact on molecular pathways are discussed.

Traditional Chinese medicine for anti-Alzheimer's disease: berberine and evodiamine from Evodia rutaecarpa

Alzheimer's disease (AD) is one of the most common diseases in elderly people with a high incidence of dementia at approximately 60-80%. The pathogenesis of AD was quite complicated and currently there is no unified conclusion in the academic community, so no efficiently clinical treatment is available. In recent years, with the development of traditional Chinese medicine (TCM), researchers have proposed the idea of relying on TCM to prevent and treat AD based on the characteristic of multiple targets of TCM. This study reviewed the pathological hypothesis of AD and the potential biomarkers found in the current researches. And the potential targets of berberine and evodiamine from Evodia rutaecarpa in AD were summarized and further analyzed. A compound-targets-pathway network was carried out to clarify the mechanism of action of berberine and evodiamine for AD. Furthermore, the limitations of current researches on the TCM and AD were discussed. It is hoped that this review will provide some references for development of TCM in the prevention and treatment of AD.

Enhanced Clearance of Neurotoxic Misfolded Proteins by the Natural Compound Berberine and Its Derivatives

Background: Accumulation of misfolded proteins is a common hallmark of several neurodegenerative disorders (NDs) which results from a failure or an impairment of the protein quality control (PQC) system. The PQC system is composed by chaperones and the degradative systems (proteasome and autophagy). Mutant proteins that misfold are potentially neurotoxic, thus strategies aimed at preventing their aggregation or at enhancing their clearance are emerging as interesting therapeutic targets for NDs. Methods: We tested the natural alkaloid berberine (BBR) and some derivatives for their capability to enhance misfolded protein clearance in cell models of NDs, evaluating which degradative pathway mediates their action. Results: We found that both BBR and its semisynthetic derivatives promote degradation of mutant androgen receptor (ARpolyQ) causative of spinal and bulbar muscular atrophy, acting mainly via proteasome and preventing ARpolyQ aggregation. Overlapping effects were observed on other misfolded proteins causative of amyotrophic lateral sclerosis, frontotemporal-lobar degeneration or Huntington disease, but with selective and specific action against each different mutant protein. Conclusions: BBR and its analogues induce the clearance of misfolded proteins responsible for NDs, representing potential therapeutic tools to counteract these fatal disorders.

Berberine attenuates Aβ42-induced neuronal damage through regulating circHDAC9/miR-142-5p axis in human neuronal cells

BACKGROUND

Berberine plays a neuroprotective role in neurodegenerative diseases, including Alzheimer's disease (AD). Circular RNAs (circRNAs) function as crucial players in AD pathogenesis. In the current work, we aimed to investigate whether circRNA histone deacetylase 9 (circHDAC9) was involved in the regulation of berberine in AD.

METHODS

Cell viability and apoptosis were determined by the Cell Counting Kit-8 (CCK-8) assay and flow cytometry, respectively. Enzyme-linked immunosorbent assay (ELISA) was used to assess caspase-3 activity and the production of interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α). The levels of circHDAC9 and miR-142-5p were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Subcellular fractionation assays were performed to evaluate the localization of circHDAC9. The direct interaction between circHDAC9 and miR-142-5p was confirmed by dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays.

RESULTS

Our data indicated that circHDAC9 was indeed a circular transcript and mainly localized in the cytoplasm. 42-residue β-amyloid (Aβ42) triggered a significant down-regulation in circHDAC9 and a striking up-regulation in miR-142-5p in human neuronal (HN) cells. Berberine relieved Aβ42-induced HN cell neurotoxicity. Moreover, berberine resulted in increased circHDAC9 expression and decreased miR-142-5p level in Aβ42-treated HN cells. Berberine alleviated Aβ42-induced neuronal damage in HN cells by up-regulating circHDAC9. Furthermore, circHDAC9 acted as a molecular sponge of miR-142-5p. CircHDAC9 overexpression alleviated Aβ42-induced HN cell neurotoxicity via miR-142-5p.

CONCLUSION

Our current study suggested that berberine protected HN cell from Aβ42-induced neuronal damage at least partly through regulating the circHDAC9/miR-142-5p axis, highlighting novel evidence for the neuroprotective effect of berberine in AD.

Non-polyphenolic natural inhibitors of amyloid aggregation

Protein misfolding diseases (PMDs) are chronic and progressive, with no effective therapy so far. Aggregation and misfolding of amyloidogenic proteins are closely associated with the onset and progression of PMDs, such as amyloid-β (Aβ) in Alzheimer's disease, α-Synuclein (α-Syn) in Parkinson's disease and human islet amyloid polypeptide (hIAPP) in type 2 diabetes. Inhibiting toxic aggregation of amyloidogenic proteins is regarded as a promising therapeutic approach in PMDs. The past decade has witnessed the rapid progresses of this field, dozens of inhibitors have been screened and verified in vitro and in vivo, demonstrating inhibitory effects against the aggregation and misfolding of amyloidogenic proteins, together with beneficial effects. Natural products are major sources of small molecule amyloid inhibitors, a number of natural derived compounds have been identified with great bioactivities and translational prospects. Here, we review the non-polyphenolic natural inhibitors that potentially applicable for PMDs treatment, along with their working mechanisms. Future directions are proposed for the development and clinical applications of these inhibitors.

Hippocampal overexpression of SGK1 ameliorates spatial memory, rescues Aβ pathology and actin cytoskeleton polymerization in middle-aged APP/PS1 mice

The increasing occurrence and ineffective treatment of Alzheimer's disease (AD) has become one of the major challenges of the world. Limited studies have shown that serum- and glucocorticoid-inducible kinase 1 (SGK1) is involved in spatial memory formation and consolidation, but its role in AD-like spatial memory impairment and the related mechanisms are not clear. In this study, we first examined the age-related changes of SGK1 in the hippocampus of female APP/PS1 (AD) mice. Based on the finding and our previous finding that significant spatial memory impairment was detected in 8-month old AD mice, SGK1-overexpressing AAV (oSGK1) was constructed and injected into the hippocampus of 9-month old AD mice. One month later, the behavior alterations, Aβ production and deposit as well as changes of CA1 spine density and selected actin polymerization remodeling proteins were examined. The results showed that significant decrease of SGK1 was detected in 10-month old AD mice. The spatial memory impairment, the production and deposit of Aβ were reversed by oSGK1. Levels of hippocampal ADAM10 (α-secretase) and IDE (Aβ degradase), actin remodeling related proteins Rictor, Rac1, Cdc42 and Profilin-1 were significantly increased after oSGK1 treatment while hippocampal BACE1 (γ-secretase) and Cofilin remained unchanged. Taken together, our findings demonstrated a pivotal role of SGK1 in the treatment of AD-related memory impairment through upregulation of non- amyloidogenic processing of APP and degradation of Aβ, increase in spine plasticity related proteins, indicating increase in hippocampal SGK1 may be a potent therapeutic target against AD.

Synergistic Inhibition of Acetylcholinesterase by Alkaloids Derived from Stephaniae Tetrandrae Radix, Coptidis Rhizoma and Phellodendri Chinensis Cortex

Alkaloids having acetylcholinesterase (AChE) inhibitory activity are commonly found in traditional Chinese medicine (TCM); for example, berberine from Coptis chinensis, galantamine from Lycoris radiata, and huperzine A from Huperzia serrata. In practice of TCM, Stephaniae Tetrandrae Radix (STR) is often combined with Coptidis Rhizoma (CR) or Phellodendri Chinensis Cortex (PCC) as paired herbs during clinical application. Fangchinoline from STR and coptisine and/or berberine from CR and/or PCC are active alkaloids in inhibiting AChE. The traditional usage of paired herbs suggests the synergistic effect of fangchinoline–coptisine or fangchinoline–berberine pairing in AChE inhibition. HPLC was applied to identify the main components in herbal extracts of STR, CR, and PCC, and the AChE inhibition of their main components was determined by Ellman assay. The synergism of herb combination and active component combination was calculated by median-effect principle. Molecular docking was applied to investigate the underlying binding mechanisms of the active components with the AChE protein. It was found that fangchinoline showed AChE inhibitory potency; furthermore, fangchinoline–coptisine/berberine pairs (at ratios of 1:5, 1:2, 1:1, and 2:1) synergistically inhibited AChE; the combination index (CI) at different ratios was less than one when Fa = 0.5, suggesting synergistic inhibition of AChE. Furthermore, the molecular docking simulation supported this enzymatic inhibition. Therefore, fangchinoline–coptisine/berberine pairs, or their parental herbal mixtures, may potentially be developed as a possible therapeutic strategy for Alzheimer’s patients.

Age-related changes in hippocampal AD pathology, actin remodeling proteins and spatial memory behavior of male APP/PS1 mice

Alzheimer's disease (AD) is the most common form of dementia in the elderly, characterized by amyloid-beta (Aβ) plaques and tau neurofibrillary tangles (NFTs). Synaptic plasticity impairment is one of the early pathological events in AD. Transgenic APP/PS1 mice that overproduce Aβ are one of the most extensively used AD animal models. Many studies have investigated the roles of NTF-related p-Tau, non-amyloidogenic ADAM10, amyloidogenic BACE1, Aβ proteolytic NEP and IDE in certain ages of APP/PS1 mice as well as dendritic spine-related Rictor and Profilin-1 in normal mice, but there are few studies exploring the age-related changes of these molecules in the hippocampus of APP/PS1 mice. Furthermore, current studies regarding when memory impairment occurs in these mice are controversial. Thus, we examined the changes of these molecules in APP/PS1 and control mice using Western blot in mice 2-month-old (2 m) to 10 m of age and behavior changes using the Morris water maze from 4 m to 8 m. The results showed that in APP/PS1 mice, significant changes of hippocampal p-Tau, Aβ, ADAM10, BACE1 and Rictor occurred at 6 m, NEP at 8 m, and IDE and Profilin-1 at 10 m. In control mice, changes of p-Tau, ADAM10, and BACE1 occurred at 8 m and NEP at 10 m, while IDE, Rictor and Profilin-1 remained unchanged. Importantly, the Morris water maze test revealed that spatial memory impairment was detected at 8 m but not 4 or 6 m. The above findings clearly evidence that neurochemical changes overtly precede cognitive dysfunctions in this AD model and provide novel knowledge for a better understanding of the molecular events driving AD.

Functions of 'A disintegrin and metalloproteases (ADAMs)' in the mammalian nervous system

'A disintegrin and metalloproteases' (ADAMs) are a family of transmembrane proteins with diverse functions in multicellular organisms. About half of the ADAMs are active metalloproteases and cleave numerous cell surface proteins, including growth factors, receptors, cytokines and cell adhesion proteins. The other ADAMs have no catalytic activity and function as adhesion proteins or receptors. Some ADAMs are ubiquitously expressed, others are expressed tissue specifically. This review highlights functions of ADAMs in the mammalian nervous system, including their links to diseases. The non-proteolytic ADAM11, ADAM22 and ADAM23 have key functions in neural development, myelination and synaptic transmission and are linked to epilepsy. Among the proteolytic ADAMs, ADAM10 is the best characterized one due to its substrates Notch and amyloid precursor protein, where cleavage is required for nervous system development or linked to Alzheimer's disease (AD), respectively. Recent work demonstrates that ADAM10 has additional substrates and functions in the nervous system and its substrate selectivity may be regulated by tetraspanins. New roles for other proteolytic ADAMs in the nervous system are also emerging. For example, ADAM8 and ADAM17 are involved in neuroinflammation. ADAM17 additionally regulates neurite outgrowth and myelination and its activity is controlled by iRhoms. ADAM19 and ADAM21 function in regenerative processes upon neuronal injury. Several ADAMs, including ADAM9, ADAM10, ADAM15 and ADAM30, are potential drug targets for AD. Taken together, this review summarizes recent progress concerning substrates and functions of ADAMs in the nervous system and their use as drug targets for neurological and psychiatric diseases.

Rhizoma Coptidis for Alzheimer's Disease and Vascular Dementia: A Literature Review

BACKGROUND

Alzheimer's disease (AD) and vascular dementia (VaD) are major types of dementia, both of which cause heavy economic burdens for families and society. However, no currently available medicines can control dementia progression. Rhizoma coptidis, a Chinese herbal medicine, has been used for >2000 years and is now gaining attention as a potential treatment for AD and VaD.

METHODS

We reviewed the mechanisms of the active ingredients of Rhizoma coptidis and Rhizoma coptidis-containing Chinese herbal compounds in the treatment of AD and VaD. We focused on studies on ameliorating the risk factors and the pathological changes of these diseases.

RESULTS

The Rhizoma coptidis active ingredients include berberine, palmatine, coptisine, epiberberine, jatrorrhizine and protopine. The most widely studied ingredient is berberine, which has extensive therapeutic effects on the risk factors and pathogenesis of dementia. It can control blood glucose and lipid levels, regulate blood pressure, ameliorate atherosclerosis, inhibit cholinesterase activity, Aβ generation, and tau hyperphosphorylation, decrease neuroinflammation and oxidative stress and alleviate cognitive impairment. Other ingredients (such as jatrorrhizine, coptisine, epiberberine and palmatine) also regulate blood lipids and blood pressure; however, there are relatively few studies on them. Rhizoma coptidis-containing Chinese herbal compounds like Huanglian-Jie-Du-Tang, Huanglian Wendan Decoction, Banxia Xiexin Decoction and Huannao Yicong Formula have anti-inflammatory and antioxidant stress activities, regulate insulin signaling, inhibit γ-secretase activity, neuronal apoptosis, tau hyperphosphorylation, and Aβ deposition, and promote neural stem cell differentiation, thereby improving cognitive function.

CONCLUSION

The "One-Molecule, One-Target" paradigm has suffered heavy setbacks, but a "multitarget- directed ligands" strategy may be viable. Rhizoma coptidis active ingredients and Rhizoma coptidiscontaining Chinese herbal compounds have multi-aspect therapeutic effects on AD and VaD.

Neuropeptide S Ameliorates Cognitive Impairment of APP/PS1 Transgenic Mice by Promoting Synaptic Plasticity and Reducing Aβ Deposition

Alzheimer’s disease (AD) is a devastating disease in the elderly with no known effective treatment. It is characterized by progressive deterioration of memory and cognition. Many new potential targets are being investigated to develop effective therapeutic strategies for AD. Neuropeptide S (NPS) is an endogenous peptide in the central nervous system, which has been shown to play a beneficial role in learning and memory. However, whether NPS can ameliorate cognitive deficits in AD remains unclear. In this study, we examined the effects of NPS treatment on the cognitive behaviors and pathological hallmarks in 8-month-old APPswe/PS1dE9 (APP/PS1) AD mice. We found that the APP/PS1 mice exhibited lower levels of NPS receptors (NPSRs) in the hippocampal area, and NPS administration increased c-Fos expression in the hippocampus and cortex, which suggests the NPS/NPSR system may contribute to the pathogenesis of AD. After an intracerebroventricular injection of NPS (1 nmol) for 2 weeks, we found NPS treatment ameliorated spatial memory deficits and promoted dendrite ramification and spine generation in hippocampal CA1 neurons, which was accompanied by the upregulation of postsynaptic density protein 95 (PSD95) and synapsin1. We also demonstrated that the injection of NPS decreased Aβ plaque deposits by decreasing the γ-secretase activity and the phosphorylation of APP at Thr668. Furthermore, application of NPS reversed the deficits in hippocampal late-phase long-term potentiation (LTP). These findings suggest NPS attenuated cognitive deficits by reducing pathological features in APP/PS1 mice, and NPS might be a potential therapeutic agent for AD.

Berberine Alleviates Amyloid-beta Pathogenesis Via Activating LKB1/AMPK Signaling in the Brain of APP/PS1 Transgenic Mice

Background:

Liver kinase B1 (LKB1)/5’-adenosine monophosphate-activated protein kinase (AMPK) signaling, a metabolic checkpoint, plays a neuro-protective role in the pathogenesis of Alzheimer’s disease (AD). Amyloid-β (Aβ) acts as a classical biomarker of AD. The aim of the present study was to explore whether berberine (BBR) activates LKB1/AMPK signaling and ameliorates Aβ pathology.

Methods:

The Aβ levels were detected using enzyme-linked immunosorbent assay and immunohistochemistry. The following biomarkers were measured by Western blotting: phosphorylated (p-) LKB1 (Ser334 and Thr189), p-AMPK (AMPKα and AMPKβ1), synaptophysin, post-synaptic density protein 95 and p-cAMP-response element binding protein (p-CREB). The glial fibrillary acidic protein (GFAP) was determined using Western blotting and immunohistochemistry.

Results:

BBR inhibited Aβ expression in the brain of APP/PS1 mice. There was a strong up-regulation of both p-LKB1 (Ser334 and Thr189) and p-AMPK (AMPKα and AMPKβ1) in the brains of APP/PS1 transgenic mice after BBR-treatment (P<0.01). BBR promoted the expression of synaptophysin, post-synaptic density protein 95 and p-CREB(Ser133) in the AD brain, compared with the model mice.

Conclusion:

BBR alleviates Aβ pathogenesis and rescues synapse damage via activating LKB1/AMPK signaling in the brain of APP/PS1 transgenic mice.

Electroacupuncture Mitigates Hippocampal Cognitive Impairments by Reducing BACE1 Deposition and Activating PKA in APP/PS1 Double Transgenic Mice

Increased amyloid-β (Aβ) plaque deposition is thought to be the main cause of Alzheimer's disease (AD). β-Site amyloid precursor protein cleaving enzyme 1 (BACE1) is the key protein involved in Aβ peptide generation. Excessive expression of BACE1 might cause overproduction of neurotoxins in the central nervous system. Previous studies indicated that BACE1 initially cleaves the amyloid precursor protein (APP) and may subsequently interfere with physiological functions of proteins such as PKA, which is recognized to be closely associated with long-term potentiation (LTP) level and can effectively ameliorate cognitive impairments. Therefore, revealing the underlying mechanism of BACE1 in the pathogenesis of AD might have a significant impact on the future development of therapeutic agents targeting dementia. This study examined the effects of electroacupuncture (EA) stimulation on BACE1, APP, and p-PKA protein levels in hippocampal tissue samples. Memory and learning abilities were assessed using the Morris water maze test after EA intervention. Immunofluorescence, immunohistochemistry, and western blot were employed to assess the distribution patterns and expression levels of BACE1, APP, and p-PKA, respectively. The results showed the downregulation of BACE1 and APP and the activation of PKA by EA. In summary, EA treatment might reduce BACE1 deposition in APP/PS1 transgenic mice and regulate PKA and its associated substrates, such as LTP to change memory and learning abilities.