Therapeutics of Neurotransmitters in Alzheimer's Disease

The Monkey Head Mushroom and Memory Enhancement in Alzheimer’s Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder, and no effective treatments are available to treat this disorder. Therefore, researchers have been investigating Hericium erinaceus, or the monkey head mushroom, an edible medicinal mushroom, as a possible treatment for AD. In this narrative review, we evaluated six preclinical and three clinical studies of the therapeutic effects of Hericium erinaceus on AD. Preclinical trials have successfully demonstrated that extracts and bioactive compounds of Hericium erinaceus have potential beneficial effects in ameliorating cognitive functioning and behavioral deficits in animal models of AD. A limited number of clinical studies have been conducted and several clinical trials are ongoing, which have thus far shown analogous outcomes to the preclinical studies. Nonetheless, future research on Hericium erinaceus needs to focus on elucidating the specific neuroprotective mechanisms and the target sites in AD. Additionally, standardized treatment parameters and universal regulatory systems need to be established to further ensure treatment safety and efficacy. In conclusion, Hericium erinaceus has therapeutic potential and may facilitate memory enhancement in patients with AD.

Cornuside ameliorates cognitive impairments in scopolamine induced AD mice: Involvement of neurotransmitter and oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis Sieb. et Zucc., traditional Chinese medicine, has been widely used in the treatment of dementia. Cornel iridoid glycosides of Cornus officinalis is therapeutic to Alzheimer's disease (AD), while its pharmacodynamic material basis is not clear. Cornuside, an iridoid glycoside extracted from of Cornus officinalis Sieb. et Zucc, might be a potential anti-AD candidate.

AIM OF THE STUDY

Cornuside was evaluated for its effect on scopolamine induced AD mice, and its action mechanisms were explored.

MATERIALS AND METHODS

ICR mice were administered with 1 mg/kg scopolamine intraperitoneally to induce amnesia. The therapeutic effect of cornuside of cognitive function was evaluated via series of behavioral tests, including Morris water maze test, step-through test and step-down test. In addition, specific enzyme reaction tests were used to detect the content of acetylcholine (ACh) and malondialdehyde (MDA), as well as the activities of acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), choline acetyltransferase (ChAT), superoxide dismutase (SOD), catalase (CAT), monoamine oxidase (MAO) in the brain. The levels of monoamine neurotransmitters were detected by high performance liquid chromatography-electrochemical detection (HPLC-ECD).

RESULTS

Cornuside ameliorated the spatial memory impairment in Morris water maze test and cognitive disruption in step-through and step-down test. Furthermore, cornuside improved the level of ACh by reducing the activities of AChE and BuChE, and increasing the activity of ChAT in hippocampus. Cornuside also increased the levels of monoamine neurotransmitters by inhibiting MAO activity in hippocampus and cortex. In addition, cornuside attenuated MDA by enhancing the activities of SOD and CAT in hippocampus and cortex.

CONCLUSION

Cornuside improved cognitive dysfunction induced by scopolamine in behavioral tests. The mechanisms of cornuside were further investigated from the aspects of neurotransmitters and oxidative stress. Cornuside could inhibit oxidative stress and neurotransmitter hydrolases, increase ACh and monoamine neurotransmitters, which finally contributed to its therapeutic effect on scopolamine induced amnesia.

Natural Product-based Nanomedicine: Recent Advances and Issues for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) affects the elderly and is characterized by progressive neurodegeneration caused by different pathologies. The most significant challenges in treating AD include the inability of medications to reach the brain because of its poor solubility, low bioavailability, and the presence of the blood-brain barrier (BBB). Additionally, current evidence suggests the disruption of BBB plays an important role in the pathogenesis of AD. One of the critical challenges in treating AD is the ineffective treatments and their severe adverse effects. Nanotechnology offers an alternative approach to facilitate the treatment of AD by overcoming the challenges in drug transport across the BBB. Various nanoparticles (NP) loaded with natural products were reported to aid in drug delivery for the treatment of AD. The nano-sized entities of NP are great platforms for incorporating active materials from natural products into formulations that can be delivered effectively to the intended action site without compromising the material's bioactivity. The review highlights the applications of medicinal plants, their derived components, and various nanomedicinebased approaches for the treatment of AD. The combination of medicinal plants and nanotechnology may lead to new theragnostic solutions for the treatment of AD in the future.

Hypoxic and Hypercapnic Responses in Transgenic Murine Model of Alzheimer’s Disease Overexpressing Human AβPP: The Effects of Pretreatment with Memantine and Rivastigmine

Despite the severe respiratory problems reducing the quality of life for Alzheimer’s disease (AD) patients, their causes are poorly understood. We aimed to investigate hypoxic and hypercapnic respiratory responses in a transgenic mouse model of AD (AβPP V717I) overexpressing AβPP and mimicking early-onset AD. The cholinesterase inhibitor rivastigmine and the NMDA receptor antagonist memantine were used to investigate the effects of drugs, used to treat AD cognitive dysfunction, on breathing in hypoxia and hypercapnia. We found a significant increase in the respiratory response to hypercapnia and no difference in the hypoxic response in APP+ mice, compared with the control group (APP−). Memantine had no effect on respiration in either group, including responses to hypoxia and hypercapnia. Rivastigmine depressed resting ventilation and response to hypercapnia irrespective of the mice genotype. Reduction in hypoxia-augmented ventilation by rivastigmine was observed only in APP+ mice, which exhibited lower acetylcholinesterase activity in the hippocampus. Treatment with rivastigmine reduced the enzyme activity in both groups equally in the hippocampus and brainstem. The increased ventilatory response to hypercapnia in transgenic mice may indicate alterations in chemoreceptive respiratory nuclei, resulting in increased CO₂ sensitivity. Rivastigmine is a potent reductant of normoxic and hypercapnic respiration in APP+ and APP− mice.

Novel Cyclopentaquinoline and Acridine Analogs as Multifunctional, Potent Drug Candidates in Alzheimer's Disease

A series of new cyclopentaquinoline derivatives with 9-acridinecarboxylic acid and a different alkyl chain length were synthesized, and their ability to inhibit cholinesterases was evaluated. All designed compounds, except derivative 3f, exhibited a selectivity for butyrylcholinesterase (BuChE) with IC₅₀ values ranging from 103 to 539 nM. The 3b derivative revealed the highest inhibitory activity towards BuChE (IC₅₀ = 103.73 nM) and a suitable activity against AChE (IC₅₀ = 272.33 nM). The 3f derivative was the most active compound to AChE (IC₅₀ = 113.34 nM) with satisfactory activity towards BuChE (IC₅₀ = 203.52 nM). The potential hepatotoxic effect was evaluated for both 3b and 3f compounds. The 3b and 3f potential antioxidant activity was measured using the ORAC-FL method. The 3b and 3f derivatives revealed a significantly higher antioxidant potency, respectively 35 and 25 higher than tacrine. Theoretical, physicochemical, and pharmacokinetic properties were calculated using ACD Labs Percepta software. Molecular modeling and kinetic study were used to reveal the mechanism of cholinesterase inhibition in the most potent compounds: 3b and 3f.

Sleep-Wake Disorders in Alzheimer's Disease: A Review

Alzheimer's disease (AD) is a multifactorial disease, and it has become a serious health problem in the world. Senile plaques (SPs) and neurofibrillary tangles (NFTs) are two main pathological characters of AD. SP mainly consists of aggregated β-amyloid (Aβ), and NFT is formed by hyperphosphorylated tau protein. Sleep-wake disorders are prevalent in AD patients; however, the links and mechanisms of sleep-wake disorders on the AD pathogenesis remain to be investigated. Here, we referred to the sleep-wake disorders and reviewed some evidence to demonstrate the relationship between sleep-wake disorders and the pathogenesis of AD. On one hand, the sleep-wake disorders may lead to the increase of Aβ production and the decrease of Aβ clearance, the spreading of tau pathology, as well as oxidative stress and inflammation. On the other hand, the ApoE4 allele, a risk gene for AD, was reported to participate in sleep-wake disorders. Furthermore, some neurotransmitters, such as acetylcholine, glutamate, serotonin, melatonin, and orexins, and their receptors were suggested to be involved in AD development and sleep-wake disorders. We discussed and suggested some possible therapeutic strategies for AD treatment based on the view of sleep regulation. In general, this review explored different views to find novel targets of diagnosis and therapy for AD.

Novel and Potent Acetylcholinesterase Inhibitors for the Treatment of Alzheimer's Disease from Natural (±)-7,8-Dihydroxy-3-methyl-isochroman-4-one

Alzheimer’s disease (AD) is a neurodegenerative disease that causes memory and cognitive decline as well as behavioral problems. It is a progressive and well recognized complex disease; therefore, it is very urgent to develop novel and effective anti-AD drugs. In this study, a series of novel isochroman-4-one derivatives from natural (±)-7,8-dihydroxy-3-methyl-isochroman-4-one [(±)-XJP] were designed and synthesized, and their anti-AD potential was evaluated. Among them, compound 10a [(Z)-3-acetyl-1-benzyl-4-((6,7-dimethoxy-4-oxoisochroman-3-ylidene)methyl)pyridin-1-ium bromide] possessed potent anti-acetylcholinesterase (AChE) activity as well as modest antioxidant activity. Further molecular modeling and kinetic investigations revealed that compound 10a was a dual-binding inhibitor that binds to both catalytic anionic site (CAS) and peripheral anionic site (PAS) of the enzyme AChE. In addition, compound 10a exhibited low cytotoxicity and moderate anti-Aβ aggregation efficacy. Moreover, the in silico screening suggested that these compounds could pass across the blood–brain barrier with high penetration. These findings show that compound 10a was a promising lead from a natural product with potent AChE inhibitory activity and deserves to be further developed for the prevention and treatment of AD.

Amelioration of cognitive and biochemical impairment in Aβ-based rodent model of Alzheimer's disease following fractionated X-irradiation

Alzheimer's disease is characterized by deposition of amyloid-beta plaques in the brain. Available pharmaceuticals provide temporary symptomatic relief without affecting disease progression. Use of radiation was found effective in treating extra-cranial amyloidosis, therefore, the present study was designed to investigate the neuroprotective role of fractionated X-irradiation in Aβ_1-42-based rodent model of Alzheimer's disease. S.D. female rats were randomly divided into four groups: sham control (Group 1), Aβ_1-42 injected (Group 2), cranial X-irradiated (Group 3) and Aβ_1-42 injected followed by cranial X-irradiation (Group 4). A single dose of 5 µL Aβ_1-42 peptide was administered through intracerebroventricular (icv) injection in Group 2 and 4 animals, while Group 1 animals were administered 5 µL of bi-distilled water (icv). The group 4 animals were further subjected to 10 Gy X-irradiation (fractionated dose, 2 Gy × 5 days) after 4 weeks of Aβ_1-42 infusion of peptide. The animals in Group 3 were subjected to same dose of cranial fractionated X-irradiation (2 Gy × 5 days) only. Significant decrease in amyloid deposits were observed in the Aβ_1-42 + radiation-treated animals confirmed by histopathological analysis. These finding were in concordance with neurobehavioral tests that showed a significant improvement in Aβ_1-42-induced memory impairment in the animals subjected to fractionated cranial X-irradiation. Restoration of alterations in neurochemical and antioxidant defense indices further supported our results. The present study highlights the underexplored role of fractionated X-irradiation in curtailing the Aβ_1-42-induced neurotoxicity, suggesting a novel treatment option for Alzheimer's disease-associated pathologies.

Unveiling the Multitarget Anti-Alzheimer Drug Discovery Landscape: A Bibliometric Analysis

Multitarget anti-Alzheimer agents are the focus of very intensive research. Through a comprehensive bibliometric analysis of the publications in the period 1990-2020, we have identified trends and potential gaps that might guide future directions. We found that: (i) the number of publications boomed by 2011 and continued ascending in 2020; (ii) the linked-pharmacophore strategy was preferred over design approaches based on fusing or merging pharmacophores or privileged structures; (iii) a significant number of in vivo studies, mainly using the scopolamine-induced amnesia mouse model, have been performed, especially since 2017; (iv) China, Italy and Spain are the countries with the largest total number of publications on this topic, whereas Portugal, Spain and Italy are the countries in whose scientific communities this topic has generated greatest interest; (v) acetylcholinesterase, β-amyloid aggregation, oxidative stress, butyrylcholinesterase, and biometal chelation and the binary combinations thereof have been the most commonly pursued, while combinations based on other key targets, such as tau aggregation, glycogen synthase kinase-3β, NMDA receptors, and more than 70 other targets have been only marginally considered. These results might allow us to spot new design opportunities based on innovative target combinations to expand and diversify the repertoire of multitarget drug candidates and increase the likelihood of finding effective therapies for this devastating disease.

Sex Differences in Demographic and Pharmacological Factors in Alzheimer Patients With Dementia and Cognitive Impairments

Objective

The current study investigates sex differences associated with pharmacological and demographic characteristics in Alzheimer patients (AD) with dementia (ADD) or mild cognitive impairment (MCI).

Method

A retrospective analytical approach was used to analyze data from 45,696 AD patients with MCI or ADD. The univariate analysis was used to determine differences in demographic, and pharmacological characteristics for male and female ADD and MCI-AD patients. Multivariate analysis was used to predict specific pharmacological and demographic factors that are associated with male and female MCI and ADD patients.

Result

In the adjusted analysis for male patients, Hispanics [0.166,0.020 – 1.355, P = 0.094] or African Americans [OR = 2.380, 95% CI,2.120 – 2.674, P < 0.001], were more likely to have MCI-AD and be treated with galantamine [OR = 0.559, 95% CI, 0.382 – 0.818, P = 0.003], donepezil [OR = 1.639, 95% CI,1.503 – 1.787, P < 0.001], rivastigmine [OR = 1.394, 95% CI,1.184 – 1.642, P < 0.001], olanzapine [OR = 2.727, 95% CI,2.315 – 3.212, P < 0.001], risperidone [OR = 2.973, 95% CI,2.506 – 3.526, P < 0.001], present with increasing age [1.075,1.071 – 1.079, P < 0.001], and are on tobacco use [OR = 1.150, 95% CI,1.054 – 1.254, P = 0.002]. For female patients, buspirone [OR = 0.767, 95% CI, 0.683 – 0.861, P < 0.001] and a history of alcohol (ETOH) use [OR = 0.484, 95% CI, 0.442 – 0.529, P < 0.001] were associated with MCI-AD. Increasing age [OR = 1.096, 95% CI, 1.093 – 1.100, P < 0.001], donepezil [OR = 2.185, 95% CI, 2.035 – 2.346, P < 0.001], memantine [OR = 2.283, 95% CI, 2.104 – 2.477, P < 0.001] aripiprazole [OR = 1.807, 95% CI, 1.544 – 2.113, P < 0.001] olanzapine [OR = 2.289, 95% CI, 1.986 – 2.640, P < 0.001] risperidone [OR = 2.548, 95% CI, 2.246 – 2.889, P < 0.001] buspirone [OR = 0.767, 95% CI, 0.683 – 0.861, P < 0.001] escitalopram [OR = 1.213, 95% CI,1.119 – 1.315, P < 0.001] African Americans [OR = 1.395, 95% CI, 1.268 – 1.535, P < 0.001] and tobacco use [OR = 1.150, 95% CI, 1.073 – 1.233, P < 0.001] were associated with ADD.

Conclusion

Our findings reveal that MCI-AD patients were more likely to be Hispanics or African American males treated with rivastigmine, olanzapine and citalopram. African American females were associated with ADD and more likely to be treated with buspirone and presented with a history of ETOH. This finding suggests the need for a pharmacological treatment approach encompassing sex-sensitive strategies for MCI-AD and ADD patients.

Personalized Management and Treatment of Alzheimer's Disease

Alzheimer’s disease (AD) is a priority health problem with a high cost to society and a large consumption of medical and social resources. The management of AD patients is complex and multidisciplinary. Over 90% of patients suffer from concomitant diseases and require personalized therapeutic regimens to reduce adverse drug reactions (ADRs), drug−drug interactions (DDIs), and unnecessary costs. Men and women show substantial differences in their AD-related phenotypes. Genomic, epigenetic, neuroimaging, and biochemical biomarkers are useful for predictive and differential diagnosis. The most frequent concomitant diseases include hypertension (>25%), obesity (>70%), diabetes mellitus type 2 (>25%), hypercholesterolemia (40%), hypertriglyceridemia (20%), metabolic syndrome (20%), hepatobiliary disorder (15%), endocrine/metabolic disorders (>20%), cardiovascular disorder (40%), cerebrovascular disorder (60−90%), neuropsychiatric disorders (60−90%), and cancer (10%). Over 90% of AD patients require multifactorial treatments with risk of ADRs and DDIs. The implementation of pharmacogenetics in clinical practice can help optimize the limited therapeutic resources available to treat AD and personalize the use of anti-dementia drugs, in combination with other medications, for the treatment of concomitant disorders.

PAYCS Alleviates Scopolamine-Induced Memory Deficits in Mice by Reducing Oxidative and Inflammatory Stress and Modulation of Gut Microbiota-Fecal Metabolites-Brain Neurotransmitter Axis

The bioactive peptide PAYCS (Pro-Ala-Tyr-Cys-Ser) identified from anchovy hydrolysates has been reported to be positive in memory alleviation. The gut microbiota-brain axis plays a vital role in brain functions, which could be affected by nutritional supplementation. Herein, we found that PAYCS at different concentrations (PAYCS-L and PAYCS-H) showed various improving effects in behavioral tests and alleviation effects on oxidative as well as inflammatory stress in the scopolamine-induced AD mouse model. The 16S rRNA results illustrated that PAYCS-L altered the ratio of Bacteroidetes/Firmicutes and PAYCS treatment elevated the relative abundance of Cacteroidaceae and Prevotellaceae. Notably, administration of PAYCS significantly upregulated memory-related metabolites and neurotransmitters. Overall, PAYCS-L reversed memory deficits of amnesiac mice partially via the modulation of gut microbiota-metabolites-brain neurotransmitter axis. For PAYCS-H, functions might be involved in the reversal of oxidative and inflammatory impairments in the liver and serum, which was also associated with the changed intestinal microbiota and fecal metabolites.

Neuroprotective Effect of Luteolin-7-O-Glucoside against 6-OHDA-Induced Damage in Undifferentiated and RA-Differentiated SH-SY5Y Cells

Luteolin is one of the most common flavonoids present in edible plants and its potential benefits to the central nervous system include decrease of microglia activation, neuronal damage and high antioxidant properties. The aim of this research was to evaluate the neuroprotective, antioxidant and anti-inflammatory activities of luteolin-7-O-glucoside (Lut7). Undifferentiated and retinoic acid (RA)-differentiated SH-SY5Y cells were pretreated with Lut7 and incubated with 6-hydroxydopamine (6-OHDA). Cytotoxic and neuroprotective effects were determined by MTT assay. Antioxidant capacity was determined by DPPH, FRAP, and ORAC assays. ROS production, mitochondrial membrane potential (ΔΨm), Caspase–3 activity, acetylcholinesterase inhibition (AChEI) and nuclear damage were also determined in SH-SY5Y cells. TNF-α, IL-6 and IL-10 release were evaluated in LPS-induced RAW264.7 cells by ELISA. In undifferentiated SH-SY5Y cells, Lut7 increased cell viability after 24 h, while in RA-differentiated SH-SY5Y cells, Lut7 increased cell viability after 24 and 48 h. Lut7 showed a high antioxidant activity when compared with synthetic antioxidants. In undifferentiated cells, Lut7 prevented mitochondrial membrane depolarization induced by 6-OHDA treatment, decreased Caspase-3 and AChE activity, and inhibited nuclear condensation and fragmentation. In LPS-stimulated RAW264.7 cells, Lut7 treatment reduced TNF-α levels and increased IL-10 levels after 3 and 24 h, respectively. In summary, the results suggest that Lut7 has neuroprotective effects, thus, further studies should be considered to validate its pharmacological potential in more complex models, aiming the treatment of neurodegenerative diseases.

Trévo abrogates Lead Acetate Neurotoxicity in Male Wistar Rats viz Antiamyloidogenesis, Antiglutaminergic, and Anticholinesterase Activities

Background:

Exposure to lead has been linked to biochemical changes similar to those patients suffering from Alzheimer’s disease. Trévo is a phytonutrient-rich product with antiaging and antioxidant properties.

Purpose:

To investigate the neuroprotective activity of trévo against lead-induced biochemical changes in male Wistar rats.

Methods:

The study involves 35 animals that were randomly divided into five groups of seven rats each. Group I (Control): Orally administered distilled water; Group II (Induced): Administered 15 mg/kg of lead acetate (PbA) intraperitoneally; Group III (Treatment group): Orally administered 2 mL/kg of trévo for two days before co-administration with PbA for 12 consecutive days; Group IV (Treatment group): Orally administered 5 mL/kg of trévo for two days prior to coadministration with PbA for 12 consecutive days; Group V: Orally administered 5 mL/kg of trévo for 14 consecutive days. Animals were anesthetized with diether and the brain excised and processed for the following biochemical assays: Malonedialdehyde (MDA), glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GT), acetylcholinesterase (AChE), beta-amyloid, glutamate, Na+/K+ ATPase, and glutamate dehydrogenase (GD).

Results:

PbA caused significant oxidative stress (increased MDA concentration, decreased GSH concentration, suppressed the activity of CAT, SOD), decreased GT activity, increased activity of AChE, increased the concentration of beta-amyloid, and caused glutamate excitotoxicity (increased concentration of glutamate, decreased activity of Na+/K+ ATPase, and GD) in rat brains. Treatment with trévo at the two different doses significantly prevented oxidative damage, beta-amyloid aggregation, glutamate excitotoxicity, and acetylcholine breakdown induced by lead acetate.

Conclusion:

Our findings added to the reported pharmacological activity of trévo and supported the antiaging potential of trévo.

Targeted UHPLC-ESI-MS/MS Analysis of Selected Neurotransmitters, Tryptophan and Its Metabolite Kynurenine in Tau Transgenic Rat Brain Tissue: A Pivotal Study

Neurotransmitters (NT) are widely distributed in the central nervous system. These molecules are important for many physiological processes and the function of the immune system. Imbalance of NT are linked to numerous neurological disorders and diseases, including tauopathies. Here, a targeted approach based on on-line combination of ultra-high performance liquid chromatography with tandem mass spectrometry was validated and applied to the quantitative analysis of nine NT (acetylcholine, choline, aspartic acid, asparagine, glutamic acid, glutamine, pyroglutamate, γ-aminobutyric acid, N-acetyl-L-aspartic acid), tryptophan and its metabolite kynurenine in brain tissue samples of a rat model for tauopathy. The applied analytical method was characterized by excellent validation parameters for all analytes, such as limits of detection in the range of 0.01–1.70 µg/mL, regression coefficients of the calibration curves ≥ 0.9946, intra-day and inter-day precision expressed as coefficient of variation in the range of 0.6–11.9% and 0.6–14.4%, and accuracy in the range of 87.6–107.1% and 87.2–119.6%. Our analytical approach led to the identification of increased levels of choline and γ-aminobutyric acid in pons, and elevated concentration levels of pyroglutamate in medulla oblongata. These findings indicate that NT could play a valuable role in the study and clarification of neuroinflammation and neurodegenerative diseases.

Therapeutic potential of quinazoline derivatives for Alzheimer's disease: A comprehensive review

Quinazolines are considered as a promising class of bioactive heterocyclic compounds with broad properties. Particularly, the quinazoline scaffold has an impressive role in the design and synthesis of new CNS-active drugs. The drug-like properties and pharmacological characteristics of quinazoline could lead to different drugs with various targets. Among CNS disorders, Alzheimer's disease (AD) is a progressive neurodegenerative disorder with memory loss, cognitive decline and language dysfunction. AD is a complex and multifactorial disease therefore, the need for finding multi-target drugs against this devastative disease is urgent. A literature survey revealed that quinazoline derivatives have diverse therapeutic potential for AD as modulators/inhibitors of β-amyloid, tau protein, cholinesterases, monoamine oxidases, and phosphodiesterases as well as other protective effects. Thus, we describe here the most relevant and recent studies about anti-AD agents with quinazoline structure which can further aid the development and discovery of new anti-AD agents.

Pharmacogenomics of Alzheimer's Disease: Novel Strategies for Drug Utilization and Development

Alzheimer's disease (AD) is a priority health problem in developed countries with a high cost to society. Approximately 20% of direct costs are associated with pharmacological treatment. Over 90% of patients require multifactorial treatments, with risk of adverse drug reactions (ADRs) and drug-drug interactions (DDIs) for the treatment of concomitant diseases such as hypertension (>25%), obesity (>70%), diabetes mellitus type 2 (>25%), hypercholesterolemia (40%), hypertriglyceridemia (20%), metabolic syndrome (20%), hepatobiliary disorder (15%), endocrine/metabolic disorders (>20%), cardiovascular disorder (40%), cerebrovascular disorder (60-90%), neuropsychiatric disorders (60-90%), and cancer (10%).For the past decades, pharmacological studies in search of potential treatments for AD focused on the following categories: neurotransmitter enhancers (11.38%), multitarget drugs (2.45%), anti-amyloid agents (13.30%), anti-tau agents (2.03%), natural products and derivatives (25.58%), novel synthetic drugs (8.13%), novel targets (5.66%), repository drugs (11.77%), anti-inflammatory drugs (1.20%), neuroprotective peptides (1.25%), stem cell therapy (1.85%), nanocarriers/nanotherapeutics (1.52%), and other compounds (<1%).Pharmacogenetic studies have shown that the therapeutic response to drugs in AD is genotype-specific in close association with the gene clusters that constitute the pharmacogenetic machinery (pathogenic, mechanistic, metabolic, transporter, pleiotropic genes) under the regulatory control of epigenetic mechanisms (DNA methylation, histone/chromatin remodeling, microRNA regulation). Most AD patients (>60%) are carriers of over ten pathogenic genes. The genes that most frequently (>50%) accumulate pathogenic variants in the same AD case are A2M (54.38%), ACE (78.94%), BIN1 (57.89%), CLU (63.15%), CPZ (63.15%), LHFPL6 (52.63%), MS4A4E (50.87%), MS4A6A (63.15%), PICALM (54.38%), PRNP (80.7059), and PSEN1 (77.19%). There is also an accumulation of 15 to 26 defective pharmagenes in approximately 85% of AD patients. About 50% of AD patients are carriers of at least 20 mutant pharmagenes, and over 80% are deficient metabolizers for the most common drugs, which are metabolized via the CYP2D6, CYP2C9, CYP2C19, and CYP3A4/5 enzymes.The implementation of pharmacogenetics can help optimize drug development and the limited therapeutic resources available to treat AD, and personalize the use of anti-dementia drugs in combination with other medications for the treatment of concomitant disorders.

The Gut Microbiota-Brain Axis: A New Frontier on Neuropsychiatric Disorders

Alzheimer's disease (AD) is a progressive and incurable neurodegenerative disorder of integrative areas of the brain, characterized by cognitive decline and disability resulting in negative impacts on the family of the patients and the health care services worldwide. AD involves oxidative stress, neuroinflammation and accelerated apoptosis, accompanied by deposition of amyloid-β peptide plaques and tau protein-based neurofibrillary tangles in the central nervous system. Among the multiple factors that contribute to the onset and evolution of this disease, aging stands out. That is why the prevalence of this disease has increased due to the constant increase in life expectancy. In the hope of finding new, more effective methods to slow the progression of this disease, over the last two decades, researchers have promoted "omics"-based approaches that include the gut microbiota and their reciprocal interactions with different targets in the body. This scientific advance has also led to a better understanding of brain compartments and the mechanisms that affect the integrity of the blood-brain barrier. This review aims to discuss recent advances related to the gut-brain-microbiota axis in AD. Furthermore, considering that AD involves psychiatric symptoms, this review also focuses on the psychiatric factors that interact with this axis (an issue that has not yet been sufficiently addressed in the literature).

Systems Biology to Address Unmet Medical Needs in Neurological Disorders

Neurological diseases are highly prevalent and constitute a significant cause of mortality and disability. Neurological disorders encompass a heterogeneous group of neurodegenerative conditions, broadly characterized by injury to the peripheral and/or central nervous system. Although the etiology of neurological diseases varies greatly, they share several characteristics, such as heterogeneity of clinical presentation, non-cell autonomous nature, and diversity of cellular, subcellular, and molecular pathways. Systems biology has emerged as a valuable platform for addressing the challenges of studying heterogeneous neurological diseases. Systems biology has manifold applications to address unmet medical needs for neurological illness, including integrating and correlating different large datasets covering the transcriptome, epigenome, proteome, and metabolome associated with a specific condition. This is particularly useful for disentangling the heterogeneity and complexity of neurological conditions. Hence, systems biology can help in uncovering pathophysiology to develop novel therapeutic targets and assessing the impact of known treatments on disease progression. Additionally, systems biology can identify early diagnostic biomarkers, to help diagnose neurological disease preceded by a long subclinical phase, as well as define the exposome, the collection of environmental toxicants that increase risk of certain neurological diseases. In addition to these current applications, there are numerous potential emergent uses, such as precision medicine.

Emotion Processing Dysfunction in Alzheimer's Disease: An Overview of Behavioral Findings, Systems Neural Correlates, and Underlying Neural Biology

We described behavioral studies to highlight emotional processing deficits in Alzheimer's disease (AD). The findings suggest prominent deficit in recognizing negative emotions, pronounced effect of positive emotion on enhancing memory, and a critical role of cognitive deficits in manifesting emotional processing dysfunction in AD. We reviewed imaging studies to highlight morphometric and functional markers of hippocampal circuit dysfunction in emotional processing deficits. Despite amygdala reactivity to emotional stimuli, hippocampal dysfunction conduces to deficits in emotional memory. Finally, the reviewed studies implicating major neurotransmitter systems in anxiety and depression in AD supported altered cholinergic and noradrenergic signaling in AD emotional disorders. Overall, the studies showed altered emotions early in the course of illness and suggest the need of multimodal imaging for further investigations. Particularly, longitudinal studies with multiple behavioral paradigms translatable between preclinical and clinical models would provide data to elucidate the time course and underlying neurobiology of emotion processing dysfunction in AD.

Dunalialla salina microalgea and its isolated zeaxanthin mitigate age-related dementia in rats: Modulation of neurotransmission and amyloid-β protein

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D. salina as well as its isolated zeaxanthin showed marked recovery of the D-gal-induced effect on the escape latency time.

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D. salina exerted an amelioration in the brain Aβ contents and an increase in the brain 5-HT, NE and DOP levels.

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These effects were confirmed by histopathological increase in number of viable neurons in both cerebral cortex and hippocampus.

Age-related deterioration of sensorimotor and cognitive abilities suggests that the brain undergoes regressive alterations with aging that compromise its function. Thus, the present study was designed to assess the efficacy of Dunaliella salina in counteracting D-galactose (D-gal)-induced dementia brain aging and its modulatory role in attenuating amyloid β (Aβ) protein and neurotransmitters. Aging associated dementia was generated by injection of D-gal (200 mg/kg; i.p) of rats for 8 weeks. D. salina biomass (250 mg/kg), polar (30 mg/kg), its carotenoid (30 mg/kg) fractions as well as the isolated zeaxanthin (250 μg/kg) were given orally simultaneously with D-gal for additional two weeks. Twenty-four hours after the last treatment dose; behavioral, biochemical and histopathological assessment were performed. Results showed that oral treatment of motor deficit rats with D. salina biomass and its isolated polar and carotenoid fractions showed amelioration in the motor coordination assessed by the rotarod test and in the memory and learning capabilities evaluated by Morris water maze test. D. salina also showed a reduction in brain levels of inflammatory indicators viz. interlekin-1β and inducible nitric oxide synthetase as well as brain contents of Aβ protein and myelin base protein. Likewise, oral treatment with D. salina biomass and its isolated polar and carotenoid fractions exhibited an increase in the rats’ brain neurotransmitters and their metabolites. Furthermore, histopathological investigations have confirmed all of these results. Our findings suggest that D. salina overcomes brain aging and thereby repairs age-related dementia, both for its modulating function in attenuating the Aβ protein and neurotransmitters.

The role of amyloids in Alzheimer's and Parkinson's diseases

With varying clinical symptoms, most neurodegenerative diseases are associated with abnormal loss of neurons. They share the same common pathogenic mechanisms involving misfolding and aggregation, and these visible aggregates of proteins are deposited in the central nervous system. Amyloid formation is thought to arise from partial unfolding of misfolded proteins leading to the exposure of hydrophobic surfaces, which interact with other similar structures and give rise to form dimers, oligomers, protofibrils, and eventually mature fibril aggregates. Accumulating evidence indicates that amyloid oligomers, not amyloid fibrils, are the most toxic species that causes Alzheimer's disease (AD) and Parkinson's disease (PD). AD has recently been recognized as the 'twenty-first century plague', with an incident rate of 1% at 60 years of age, which then doubles every fifth year. Currently, 5.3 million people in the US are afflicted with this disease, and the number of cases is expected to rise to 13.5 million by 2050. PD, a disorder of the brain, is the second most common form of dementia, characterized by difficulty in walking and movement. Keeping the above views in mind, in this review we have focused on the roles of amyloid in neurodegenerative diseases including AD and PD, the involvement of amyloid in mitochondrial dysfunction leading to neurodegeneration, are also considered in the review.

Identification of hub genes associated with cognition in the hippocampus of Alzheimer's Disease

Alzheimer’s Disease (AD) is a neurodegenerative disease featured by cognitive impairment. This bioinformatic analysis was used to identify hub genes related to cognitive dysfunction in AD. The gene expression profile GSE48350 in the hippocampus of AD patients aged >70 years was obtained from the Gene Expression Omnibus (GEO) database. A total of 96 differentially expressed genes (DEGs) were identified, and subjected to Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses; a protein–protein interaction (PPI) network was constructed. The DEGs were enriched in synapse-related changes. A protein cluster was teased out of PPI. Furthermore, the cognition ranked the first among all the terms of biological process (BP). Next, 4 of 10 hub genes enriched in cognition were identified. The function of these genes was validated using APP/PS1 mice. Cognitive performance was validated by Morris Water Maze (MWM), and gene expression by RT-qPCR, Cholecystokinin (CCK), Tachykinin precursor 1 (TAC1), Calbindin 1 (CALB1) were downregulated in the hippocampus. These genes can provide new directions in the research of the molecular mechanism of AD.

Neurotransmitter-stimulated neuron-derived sEVs have opposite effects on amyloid β-induced neuronal damage

The ratio of excitatory to inhibitory neurotransmitters is essential for maintaining the firing patterns of neural networks, and is strictly regulated within individual neurons and brain regions. Excitatory to inhibitory (E/I) imbalance has been shown to participate in the progression of neurodegenerative diseases, including Alzheimer's disease (AD). Glutamate excitotoxicity and GABAergic neuron dysfunction appear to be key components of the neuronal cell death that takes place in AD. Since extracellular vesicles (EVs) are now explored as an important vehicle in transmitting signals between cells, we hypothesized that the function of neuron-derived small EVs (sEVs) might be regulated by the status of neurotransmitter balance and that sEVs might affect amyloid β (Aβ) toxicity on neurons. This study aimed to reveal the effects of sEVs from unbalanced neurotransmitter-stimulated neurons on Aβ-induced toxicity. We demonstrated the opposite effects of the two groups of sEVs isolated from neurons stimulated by glutamate or GABA on Aβ toxicity in vivo and in vitro. The sEVs released from GABA-treated neurons alleviated Aβ-induced damage, while those released from glutamate-treated neurons aggravated Aβ toxicity. Furthermore, we compared the microRNA (miRNA) composition of sEVs isolated from glutamate/GABA/PBS-treated neurons. Our results showed that glutamate and GABA oppositely regulated miR-132 levels in sEVs, resulting in the opposite destiny of recipient cells challenged with Aβ. Our results indicated that manipulating the function of sEVs by different neurotransmitters may reveal the mechanisms underlying the pathogenesis of AD and provide a promising strategy for AD treatment.

Personalized brain models identify neurotransmitter receptor changes in Alzheimer's disease

Alzheimer's disease (AD) involves many neurobiological alterations from molecular to macroscopic spatial scales, but we currently lack integrative, mechanistic brain models characterizing how factors across different biological scales interact to cause clinical deterioration in a way that is subject-specific or personalized. Neurotransmitter receptors, as important signaling molecules and potential drug targets, are key mediators of interactions between many neurobiological processes altered in AD. We present a neurotransmitter receptor-enriched multifactorial brain model, which integrates spatial distribution patterns of 15 neurotransmitter receptors from post-mortem autoradiography with multiple in-vivo neuroimaging modalities (tau, amyloid-β and glucose PET, and structural, functional and arterial spin labeling MRI) in a personalized, generative, whole-brain formulation. Applying this data-driven model to a heterogeneous aged population (N = 423, ADNI data), we observed that personalized receptor-neuroimaging interactions explained about 70% (± 20%) of the across-population variance in longitudinal changes to the six neuroimaging modalities, and up to 39.7% (P < 0.003, FWE-corrected) of inter-individual variability in AD cognitive deterioration via an axis primarily affecting executive function. Notably, based on their contribution to the clinical severity in AD, we found significant functional alterations to glutamatergic interactions affecting tau accumulation and neural activity dysfunction, and GABAergic interactions concurrently affecting neural activity dysfunction, amyloid and tau distributions, as well as significant cholinergic receptor effects on tau accumulation. Overall, GABAergic alterations had the largest effect on cognitive impairment (particularly executive function) in our AD cohort (N = 25). Furthermore, we demonstrate the clinical applicability of this approach by characterizing subjects based on individualized 'fingerprints' of receptor alterations. This study introduces the first robust, data-driven framework for integrating several neurotransmitter receptors, multi-modal neuroimaging and clinical data in a flexible and interpretable brain model. It enables further understanding of the mechanistic neuropathological basis of neurodegenerative progression and heterogeneity, and constitutes a promising step towards implementing personalized, neurotransmitter-based treatments.

An integrated strategy using LC-MS/MS combined with in vivo microdialysis for the simultaneous determination of lignans of Schisandra chinensis (Turcz.) Baill. Fructus and endogenous neurotransmitters: application in pharmacokinetic and pharmacodynamic studies

Schisandra chinensis (Turcz.) Baill Fructus (SCF) is the ripe fruit of Schisandra chinensis (Turcz.) Baill, and is often used as a neuroprotective drink. Modern pharmacological studies have shown that lignans are the main bioactive components responsible for neuroprotection and have potential in the treatment of Alzheimer's disease (AD). However, the mechanism of action of SCF in the treatment of AD from the pharmacokinetics-pharmacodynamics (PK-PD) perspective remains not well established. The purpose of this study is to investigate and compare the pharmacokinetic differences of lignans in normal and AD rats, as well as to investigate their effects on neurotransmitters and their role in the treatment of AD. To achieve this goal, an integrated strategy using LC-MS/MS combined with in vivo microdialysis for the simultaneous determination of lignans of SCF and endogenous neurotransmitters has been developed and validated. The results show that the pharmacokinetic behaviors of ten lignans in the AD group were significantly different from those in the normal group. The AD group had better absorption and slower elimination than the normal group. In addition, the pharmacodynamic results of the Morris water maze (MWM) test, biochemical tests, histopathological examination, as well as immunohistochemistry analysis showed that lignans could improve the learning and memory of AD rats. The oral administration of SCF could restore the levels of the neurotransmitter parameters; seven neurotransmitters showed clockwise or counterclockwise changes with the four lignans in the hippocampal region. Taken together, the PK and PD studies based on in vivo microdialysis sampling might offer novel insights into the mechanisms of action of SCF against AD.

Neuromodulation of Memory Formation and Extinction

Memory retrieval is mediated by discharges of acetylcholine, glutamate, gammaaminobutyric acid, norepinephrine, and serotonin/5-hydroxytryptamine circuits. These projections and memory interact through engram circuits, neurobiological traces of memory. Increased excitability in engram circuits of the medial prefrontal cortex and hippocampus results in remote and recent memory retrievals, respectively. However, due to degenerated neurotransmitter projections, the excitability state of engram circuits is decreased in the patient with dementia; and thus, acquired- memory cannot be retrieved by natural cues. Here, we suggest that artificial neuropharmacological stimulations of the acquired-memory with an excitation potential higher than a natural cue can excite engram circuits in the medial prefrontal cortex, which results in the retrieval of lost memories in dementia. The neuropharmacological foundations of engram cell-mediated memory retrieval strategy in severe dementia, in line with this has also been explained. We particularly highlighted the close interactions between periaqueductal gray, locus coeruleus, raphe nuclei, and medial prefrontal cortex and basolateral amygdala as treatment targets for memory loss. Furthermore, the engram circuits projecting raphe nuclei, locus coeruleus, and pontomesencephalic tegmentum complex could be significant targets of memory editing and memory formation in the absence of experience, and a well-defined study of the neural events underlying the interaction of brain stem and memory will be relevant for such developments. We anticipate our perspective to be a starting point for more sophisticated in vivo models for neuropharmacological modulations of memory retrieval in Alzheimer's dementia.

Inhibition of Astrocytic Histamine N-Methyltransferase as a Possible Target for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) represents the principal cause of dementia among the elderly. Great efforts have been established to understand the physiopathology of AD. Changes in neurotransmitter systems in patients with AD, including cholinergic, GABAergic, serotoninergic, noradrenergic, and histaminergic changes have been reported. Interestingly, changes in the histaminergic system have been related to cognitive impairment in AD patients. The principal pathological changes in the brains of AD patients, related to the histaminergic system, are neurofibrillary degeneration of the tuberomammillary nucleus, the main source of histamine in the brain, low histamine levels, and altered signaling of its receptors. The increase of histamine levels can be achieved by inhibiting its degrading enzyme, histamine N-methyltransferase (HNMT), a cytoplasmatic enzyme located in astrocytes. Thus, increasing histamine levels could be employed in AD patients as co-therapy due to their effects on cognitive functions, neuroplasticity, neuronal survival, neurogenesis, and the degradation of amyloid beta (Aβ) peptides. In this sense, the evaluation of the impact of HNMT inhibitors on animal models of AD would be interesting, consequently highlighting its relevance.

MD2 contributes to the pathogenesis of perioperative neurocognitive disorder via the regulation of α5GABAA receptors in aged mice

BACKGROUND

Perioperative neurocognitive disorder (PND) is a long-term postoperative complication in elderly surgical patients. The underlying mechanism of PND is unclear, and no effective therapies are currently available. It is believed that neuroinflammation plays an important role in triggering PND. The secreted glycoprotein myeloid differentiation factor 2 (MD2) functions as an activator of the Toll-like receptor 4 (TLR4) inflammatory pathway, and α5GABA_A receptors (α5GABA_ARs) are known to play a key role in regulating inflammation-induced cognitive deficits. Thus, in this study, we aimed to investigate the role of MD2 in PND and determine whether α5GABA_ARs are involved in the function of MD2.

METHODS

Eighteen-month-old C57BL/6J mice were subjected to laparotomy under isoflurane anesthesia to induce PND. The Barnes maze was used to assess spatial reference learning and memory, and the expression of hippocampal MD2 was assayed by western blotting. MD2 expression was downregulated by bilateral injection of AAV-shMD2 into the hippocampus or tail vein injection of the synthetic MD2 degrading peptide Tat-CIRP-CMA (TCM) to evaluate the effect of MD2. Primary cultured neurons from brain tissue block containing cortices and hippocampus were treated with Tat-CIRP-CMA to investigate whether downregulating MD2 expression affected the expression of α5GABA_ARs. Electrophysiology was employed to measure tonic currents. For α5GABA_ARs intervention experiments, L-655,708 and L-838,417 were used to inhibit or activate α5GABA_ARs, respectively.

RESULTS

Surgery under inhaled isoflurane anesthesia induced cognitive impairments and elevated the expression of MD2 in the hippocampus. Downregulation of MD2 expression by AAV-shMD2 or Tat-CIRP-CMA improved the spatial reference learning and memory in animals subjected to anesthesia and surgery. Furthermore, Tat-CIRP-CMA treatment decreased the expression of membrane α5GABA_ARs and tonic currents in CA1 pyramidal neurons in the hippocampus. Inhibition of α5GABA_ARs by L-655,708 alleviated cognitive impairments after anesthesia and surgery. More importantly, activation of α5GABA_ARs by L-838,417 abrogated the protective effects of Tat-CIRP-CMA against anesthesia and surgery-induced spatial reference learning and memory deficits.

CONCLUSIONS

MD2 contributes to the occurrence of PND by regulating α5GABA_ARs in aged mice, and Tat-CIRP-CMA is a promising neuroprotectant against PND.

Current druggable targets for therapeutic control of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative brain disorder that has an increasingly large burden on health and social care systems. The pathophysiology involves the accumulation of extracellular amyloid-beta plaques (Aβ) and intracellular neurofibrillary tangles contributing to neuronal death and leading to cognition impairment. However, its cause remains poorly understood, and there is no cure for AD despite extensive research and billions of dollars spent over decades. Currently, there are only four US Food and Drug Administration (FDA) approved drugs and one combination therapy available in the market for the symptomatic relief of AD. Since 2003, no new drug has been approved by the FDA for the treatment of AD. Researchers continue to explore new treatments and therapeutic strategies to treat AD. The need for novel discoveries on therapeutic targets and the development of new therapeutic approaches is imminent when considering the current expectations regarding the increased number of AD cases each year and the huge financial cost amounted to healthcare. This review focused on the current status of drugs in the clinical pipeline targeting β-amyloid, tau phosphorylation, or neurotransmitter dysfunction for therapeutic control of Alzheimer's disease.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Protective effect of andrographolide against STZ induced Alzheimer's disease in experimental rats: possible neuromodulation and Aβ(1-42) analysis

STZ is a glucosamine-nitrosourea compound, causes dysfunctioning of insulin receptors in the brain and disrupts glucose metabolism, produces cognitive decline and AD-like symptoms. ICV injection of STZ causes accumulation of Aβ and cognitive dysfunctions. Andrographolide (ANDRO) is a major bioactive constituent of Andrographis paniculata, has various biological activities such as antioxidant, anti-inflammatory, anti-cholinesterase, and neuroprotective properties. The study aimed to evaluate the neuroprotective effect of ANDRO against ICV-STZ induced AD-like symptoms in rats. To conduct the study, the Wistar rat received two injections of STZ (3 mg/kg) through the ICV route. Rats were treated with three different doses of ANDRO (15, 30, and 60 mg/kg, p.o.) and donepezil (5 mg/kg, p.o.) for 14 days. The behavioral impairments were analyzed on weekly basis. Subsequently, rats were sacrificed for the assessment of biochemical (MDA, Nitrite, GSH, SOD, Catalase and AChE), neuroinflammatory markers (IL-1β, IL-16, and TNF-α), neurotransmitters (glutamate and GABA), level of Aβ_1-42 and p tau in the hippocampus on day 21st. Our result indicated that ANDRO treatment provided a protective effect against STZ induced behavioral deficits and changes in the biochemical, neuroinflammatory mediators, and neurotransmitters of the hippocampus. Further, ANDRO also reduced the level of Aβ_1-42 and p tau in the rat hippocampus. These findings suggested that the antioxidant, anti-inflammatory, anti-cholinesterase potential of ANDRO contributed to its neuroprotective effect as well as promising therapeutic candidate for the treatment of cognitive impairment and AD-like symptoms.

Neuroprotective Efficacy of Apple Cider Vinegar on Zinc-High Fat Diet-Induced Mono Amine Oxidase Alteration in Murine Model of AD

OBJECTIVE

Monoamine Oxidase (MAO), which catalyzes the oxidative deamination of amines present in the brain and peripheral tissues, is involved in the metabolism of monoamines and is vital for cognition. This study was designed to examine the protective effect of Apple Cider Vinegar (ACV) on MAO and amine neurotransmitters such as dopamine (DA), serotonin (5-HT), non-adrenaline (NA) levels.

METHOD

In this experiment, out of five groups, three groups of animals were pretreated with one of the test drugs each i.e., Chrysin (10 mg/kg), ACV (0.7% v/v) and Rivastigmine (2.5 mg/kg) along with Zn with high fat diet (HFD) for 3 months and the rest two groups were that of control and disease induced. After the treatment period, mice were examined for MAO-A & B, DA, 5-HT and NA level estimation.

RESULTS

The results showed that Zn with HFD had induced a significant increase (p < 0.01, p < 0.001) in MAO-A & B levels and a significant decrease (p < 0.001) in the levels of 5-HT, DA, and NA. Pretreatment of test drugs with Zn with HFD caused a restoration activity and a significant decrease (p < 0.01, p < 0.05) in MAO-A & B levels and a significant increase (p < 0.05, p < 0.01, p < 0.001) in the level of DA, 5HT and NA as compared to the Zn treated group. Amongst all three test drugs mentioned above, the ACV-treated group showed the most improvement during pretreatment.

CONCLUSIONS

The findings suggest that ACV, might prove to be a beneficial nutraceutical & provide a protective effect against Alzheimer's disease (AD)-like neurological diseases.

Combination of Polygoni Multiflori Radix Praeparata and Acori Tatarinowii Rhizoma Alleviates Learning and Memory Impairment in Scopolamine-Treated Mice by Regulating Synaptic-Related Proteins

Polygoni Multiflori Radix Praeparata (ZhiHeShouWu, PMRP) and Acori Tatarinowii Rhizoma (ShiChangPu, ATR) and their traditional combination (PA) are frequently used in traditional Chinese medicine to prevent and treat Alzheimer disease (AD) based on the theory that PMRP tonifies the kidney and ATR dissipates phlegm. However, the components of PA and their mechanisms of action are not known. The present study analyzed the active components of PA, and investigated the protective effect of PA against cognitive impairment induced by scopolamine in mice along with the underlying mechanism.The aqueous extract of PA was analyzed by high-performance liquid chromatography–mass spectrometry (HPLC-MS) and gas chromatography (GC)-MS in order to identify the major components. To evaluate the protective effect of PA against cognitive dysfunction, mice were orally administered PA, PMRP, or ATR for 30 days before treatment with scopolamine. Learning and memory were assessed in mice with the Morris water maze test; neurotransmitter levels in the hippocampus were analyzed by HPLC-MS; and the expression of synapse-related proteins in the hippocampus was detected by western blotting and immunohistochemistry. Eight active compounds in PA and rat plasma were identified by HPLC-MS and GC-MS. Plasma concentrations of 2,3,5,4′-tetrahydroxystilbene-2-O-β-d-glucoside, emodin, α-asarone, and asarylaldehyde were increased following PA administration; meanwhile, gallic acid, emodin-8-O-β-d-glucopyranoside, β-asarone, and cis-methyl isoeugenol concentrations were similar in rats treated with PA, PMRP, and ATR. In scopolamine-treated mice, PA increased the concentrations of neurotransmitters in the hippocampus, activated the brain-derived neurotrophic factor (BDNF)/extracellular signal-regulated kinase (ERK)/cAMP response element binding protein (CREB) signaling pathway, and increased the expression of p90 ribosomal S6 kinase (p90RSK) and postsynaptic density (PSD)95 proteins. Thus, PA alleviates cognitive deficits by enhancing synaptic-related proteins, suggesting that it has therapeutic potential for the treatment of aging-related diseases such as AD.

Roles and Mechanisms of Axon-Guidance Molecules in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease that is characterized by progressive memory decline and cognitive dysfunctions. Although the causes of AD have not yet been established, many mechanisms have been proposed. Axon-guidance molecules play the roles in the occurrence and development of AD by participating in different mechanisms. Therefore, what roles do axon-guidance molecules play in AD? This study aimed at elucidating how axon-guidance molecules Netrins, Slits, Semaphorins, and Ephrins regulate the levels of Aβ, hyperphosphorylation of tau protein, Reelin, and other ways through different signaling pathways, in order to show the roles of axon-guidance molecules in the occurrence and development of AD. And it is hoped that this study can provide a theoretical basis and new perspectives in the search for new therapeutic targets for AD.

Emerging pathogenic role of peripheral blood factors following BBB disruption in neurodegenerative disease

The responses of central nervous system (CNS) cells such as neurons and glia in neurodegenerative diseases (NDs) suggest that regulation of neuronal and glial functions could be a strategy for ND prevention and/or treatment. However, attempts to develop such therapeutics for NDs have been hindered by the challenge of blood-brain barrier (BBB) permeability and continued constitutive neuronal loss. These limitations indicate the need for additional perspectives for the prevention/treatment of NDs. In particular, the disruption of the blood-brain barrier (BBB) that accompanies NDs allows brain infiltration by peripheral factors, which may stimulate innate immune responses involved in the progression of neurodegeneration. The accumulation of blood factors like thrombin, fibrinogen, c-reactive protein (CRP) and complement components in the brain has been observed in NDs and may activate the innate immune system in the CNS. Thus, strengthening the integrity of the BBB may enhance its protective role to attenuate ND progression and functional loss. In this review, we describe the innate immune system in the CNS and the contribution of blood factors to the role of the CNS immune system in neurodegeneration and neuroprotection.

Comprehensive investigations for a potential natural prophylaxis-A cellular and murine model for apple cider vinegar against hydrogen peroxide and scopolamine induced oxidative stress

Oxidative stress is the critical marker of neurological complications such as Alzheimer's disease (AD). Apple cider vinegar (ACV) is known to have health benefits due to its antidiabetic, anti-inflammatory, and high antioxidant properties. Therefore, we hypothesized that regular consumption of ACV would protect against AD-like neurological diseases via inhibition of oxidative stress. Authors have compared the efficacy of ACV with that of Chrysin and Rivastigmine in cellular and animal studies. In the cellular study, oxidative stress was induced in Neuro2A cells (1 × 10⁷ ) via H₂ O₂ (50 μM) treatment. Subsequently, acetylcholinesterase (AChE) activity was performed, and cell viability, SOD, GSH, lipid peroxidation (MDA) levels were measured. Similarly, in the animal study, oxidative stress was introduced in Swiss albino mice (10-11 weeks old, 20-25 g, n = 30) via scopolamine (1 mg/kg). Subsequently, histopathological experiments were performed; cognitive ability, AChE activity, and SOD, GSH, and MDA levels were measured. The in vitro results indicated that ACV (2 μM) provided better protection than Chrysin and Rivstigmine in cell viability. ACV has also performed better in restoring the antioxidants markers (SOD, GSH levels) and reducing MDA and AChE levels. In the in vivo study, test compounds (ACV, Chrysin, and Rivastigmine) improved cognitive impairment, increased the SOD and GSH level, reduced the MDA level and AChE activity, and protected the cortex-hippocampal neurons from degeneration. Here also, ACV (0.7%) showed better neuroprotection than the other two compounds. Therefore, these results supported our hypothesis that moderate consumption of ACV might prove to be beneficial prophylaxis against AD-like neurological diseases.

Regulation of Melatonin and Neurotransmission in Alzheimer's Disease

Alzheimer’s disease is a neurodegenerative disorder associated with age, and is characterized by pathological markers such as amyloid-beta plaques and neurofibrillary tangles. Symptoms of AD include cognitive impairments, anxiety and depression. It has also been shown that individuals with AD have impaired neurotransmission, which may result from the accumulation of amyloid plaques and neurofibrillary tangles. Preclinical studies showed that melatonin, a monoaminergic neurotransmitter released from the pineal gland, is able to ameliorate AD pathologies and restore cognitive impairments. Theoretically, inhibition of the pathological progression of AD by melatonin treatment should also restore the impaired neurotransmission. This review aims to explore the impact of AD on neurotransmission, and whether and how melatonin can enhance neurotransmission via improving AD pathology.

Molecular docking studies of Nigella sativa L and Curcuma xanthorrhiza Roxb secondary metabolites against histamine N-methyltransferase with their ADMET prediction

OBJECTIVES

Histamine N-methyltransferase (HNMT) is an enzyme that plays a crucial role in the inactivation of histamine in central nervous system, kidneys and bronchi. Inhibition of HNMT is known to have a potential role in treating attention-deficit hyperactivity disorder, memory impairment, mental illness and neurodegenerative illnesses. Therefore, to find potential compounds that could be developed as novel HNMT inhibitors, this study conducted an in silico study of the secondary metabolites of Nigella sativa L and Curcuma xanthorrhiza Roxb.

METHODS

In this study, we conducted a molecular docking study of 36 secondary metabolites of N. sativa L and 26 secondary metabolites of C. xanthorrhiza Roxb using an in silico approach targeting HNMT protein (PDB ID: 2AOT) using AutoDockVina software. The prediction of ADMET characteristics was done using the pkCSM Online Tool.

RESULTS

This study obtained one metabolite from N. sativa L (longifolene) and seven metabolites from C. xanthorrhiza Roxb {(+)-beta-atlantone, humulene epoxide, (-)-beta-curcumene, (E)-caryophyllene, germacrone, (R)-(-)-xanthorrhizol, and (-)-beta-caryophyllene epoxide} which were predicted to have potential to be developed as HNMT inhibitors.

CONCLUSIONS

This study found several secondary metabolites of N. sativa L and C. xanthorrhiza Roxb which had activity as HNMT inhibitors. This research can likewise be utilized as a basis for further research, both in vitro, in vivo, and clinical trials related to the development of secondary metabolites from N. sativa L and C. xanthorrhiza Roxb as novel HNMT inhibitor compounds.

Microenvironment-tailored nanoassemblies for the diagnosis and therapy of neurodegenerative diseases

Neurodegenerative disorder is an illness involving neural dysfunction/death attributed to complex pathological processes, which eventually lead to the mortality of the host. It is generally recognized through features such as mitochondrial dysfunction, protein aggregation, oxidative stress, metal ions dyshomeostasis, membrane potential change, neuroinflammation and neurotransmitter impairment. The aforementioned neuronal dysregulations result in the formation of a complex neurodegenerative microenvironment (NME), and may interact with each other, hindering the performance of therapeutics for neurodegenerative disease (ND). Recently, smart nanoassemblies prepared from functional nanoparticles, which possess the ability to interfere with different NME factors, have shown great promise to enhance the diagnostic and therapeutic efficacy of NDs. Herein, this review highlights the recent advances of stimuli-responsive nanoassemblies that can effectively combat the NME for the management of ND. The first section outlined the NME properties and their interrelations that are exploitable for nanoscale targeting. The discussion is then extended to the controlled assembly of functional nanoparticles for the construction of stimuli-responsive nanoassemblies. Further, the applications of stimuli-responsive nanoassemblies for the enhanced diagnosis and therapy of ND are introduced. Finally, perspectives on the future development of NME-tailored nanomedicines are given.

Protective effects of antidepressant citalopram against abnormal APP processing and amyloid beta-induced mitochondrial dynamics, biogenesis, mitophagy and synaptic toxicities in Alzheimer's disease

The purpose of this study is to study the neuroprotective role of selective serotonin reuptake inhibitor (SSRI), citalopram, against Alzheimer's disease (AD). Multiple SSRIs, including citalopram, are reported to treat patients with depression, anxiety and AD. However, their protective cellular mechanisms have not been studied completely. In the current study, we investigated the protective role of citalopram against impaired mitochondrial dynamics, defective mitochondrial biogenesis, defective mitophagy and synaptic dysfunction in immortalized mouse primary hippocampal cells (HT22) expressing mutant APP (SWI/IND) mutations. Using quantitative RT-PCR, immunoblotting, biochemical methods and transmission electron microscopy methods, we assessed mutant full-length APP/C-terminal fragments and Aβ levels and mRNA and protein levels of mitochondrial dynamics, biogenesis, mitophagy and synaptic genes in mAPP-HT22 cells and mAPP-HT22 cells treated with citalopram. Increased levels of mRNA levels of mitochondrial fission genes, decreased levels of fusion biogenesis, autophagy, mitophagy and synaptic genes were found in mAPP-HT22 cells relative to WT-HT22 cells. However, mAPP-HT22 cells treated with citalopram compared to mAPP-HT22 cells revealed reduced levels of the mitochondrial fission genes, increased fusion, biogenesis, autophagy, mitophagy and synaptic genes. Our protein data agree with mRNA levels. Transmission electron microscopy revealed significantly increased mitochondrial numbers and reduced mitochondrial length in mAPP-HT22 cells; these were reversed in citalopram-treated mAPP-HT22 cells. Cell survival rates were increased in citalopram-treated mAPP-HT22 relative to citalopram-untreated mAPP-HT22. Further, mAPP and C-terminal fragments werealso reduced in citalopram-treated cells. These findings suggest that citalopram reduces mutant APP and Aβ and mitochondrial toxicities and may have a protective role of mutant APP and Aβ-induced injuries in patients with depression, anxiety and AD.

Personalizing the Care and Treatment of Alzheimer's Disease: An Overview

Alzheimer's disease (AD) is a progressive, complex, and multifactorial neurodegenerative disorder, still without effective and stable therapeutic strategies. Currently, available medications for AD are based on symptomatic therapy, which include acetylcholinesterase (AChE) inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonist. Additionally, medications such as antipsychotic drugs, antidepressants, sedative, and hypnotic agents, and mood stabilizers are used for the management of behavioral and psychological symptoms of dementia (BPSD). Clinical research has been extensively investigated treatments focusing on the hallmark pathology of AD, including the amyloid deposition, tau hyperphosphorylation, neuroinflammation, and vascular changes; however, so far without success, as all new potential drugs failed to show significant clinical benefit. The underlying heterogeneous etiology and diverse symptoms of AD suggest that a precision medicine strategy is required, which would take into account the complex genetic, epigenetic, and environmental landscape of each AD patient. The article provides a comprehensive overview of the literature on AD, the current and potential therapy of both cognitive symptoms as well as BPSD, with a special focus on gut microbiota and epigenetic modifications as new emerging drug targets. Their specific patterns could represent the basis for novel individually tailored approaches aimed to optimize precision medicine strategies for AD prevention and treatment. However, the successful application of precision medicine to AD demands a further extensive research of underlying pathological processes, as well as clinical and biological complexity of this multifactorial neurodegenerative disorder.

Pharmacological Screening of Viola odorata L. for Memory-Enhancing Effect via Modulation of Oxidative Stress and Inflammatory Biomarkers

Purpose: Alzheimer disease (AD) is a progressive neurodegenerative disorder that is caused by neuroinflammation and oxidative stress. The present study aimed to characterize and then investigate the memory-enhancing potential of Viola odorata methanolic extract in lipopolysaccharide (LPS)–treated mice.

Methods:V. odorata characterization was done by using the GCMS technique. Neuroinflammation was induced by the intracerebroventricular administration of LPS at a dose of 12 µg. Animals were divided randomly into six groups (n = 10). Group I was normal control, which was given vehicle. Group II was disease control, which received LPS (12 µg) via the intracerebroventricular route. Group III was standard, which was administered with donepezil (3 µg) orally for 21 days. Groups IV–VI were the treatment groups, which were administered with the extract at 100, 200, and 400 mg/kg dose levels orally respectively for 21 days. Groups III–VI received LPS (12 µg) on the first day along with their treatments. During the treatment, the animals were assessed for memory retention by employing different behavioral paradigms namely elevated plus maze, passive avoidance, foot shock and open field. Various mediators [endogenous antioxidants, neurotransmitters, and acetylcholinesterase (AChE)] involved in the pathogenesis of AD were quantified by using the UV spectrophotometric method.

Results: Extract-treated groups showed a remarkable improvement in cognitive impairment in all behavioral paradigms. Oxidative stress biomarkers, that is, superoxide dismutase, catalase, and glutathione were raised dose-dependently in the treatment groups with a dose-dependent decrease in the malonaldehyde and AChE levels in the brains of the treated animals. The treatment groups showed decreased levels of inflammatory biomarkers, that is, tumor necrosis factor–alpha, nuclear factor kappa light-chain enhancer of activated β-cells, and cyclo-oxygenase, which supports the therapeutic effectiveness of the treatment.

Conclusion: Based on behavioral, oxidative stress biomarker, and neuroinflammatory data, it is concluded that V. odorata possesses memory-enhancing activity and may prove a beneficial role in the management of AD.

Increased excitatory to inhibitory synaptic ratio in parietal cortex samples from individuals with Alzheimer's disease

Synaptic disturbances in excitatory to inhibitory (E/I) balance in forebrain circuits are thought to contribute to the progression of Alzheimer's disease (AD) and dementia, although direct evidence for such imbalance in humans is lacking. We assessed anatomical and electrophysiological synaptic E/I ratios in post-mortem parietal cortex samples from middle-aged individuals with AD (early-onset) or Down syndrome (DS) by fluorescence deconvolution tomography and microtransplantation of synaptic membranes. Both approaches revealed significantly elevated E/I ratios for AD, but not DS, versus controls. Gene expression studies in an independent AD cohort also demonstrated elevated E/I ratios in individuals with AD as compared to controls. These findings provide evidence of a marked pro-excitatory perturbation of synaptic E/I balance in AD parietal cortex, a region within the default mode network that is overly active in the disorder, and support the hypothesis that E/I imbalances disrupt cognition-related shifts in cortical activity which contribute to the intellectual decline in AD.

Modified Snake α-Neurotoxin Averts β-Amyloid Binding to α7 Nicotinic Acetylcholine Receptor and Reverses Cognitive Deficits in Alzheimer's Disease Mice

Alzheimer's disease (AD) is the most common cause of senile dementia and one of the greatest medical, social, and economic challenges. According to a dominant theory, amyloid-β (Aβ) peptide is a key AD pathogenic factor. Aβ-soluble species interfere with synaptic functions, aggregate gradually, form plaques, and trigger neurodegeneration. The AD-associated pathology affects numerous systems, though the substantial loss of cholinergic neurons and α7 nicotinic receptors (α7AChR) is critical for the gradual cognitive decline. Aβ binds to α7AChR under various experimental settings; nevertheless, the functional significance of this interaction is ambiguous. Whereas the capability of low Aβ concentrations to activate α7AChR is functionally beneficial, extensive brain exposure to high Aβ concentrations diminishes α7AChR activity, contributes to the cholinergic deficits that characterize AD. Aβ and snake α-neurotoxins competitively bind to α7AChR. Accordingly, we designed a chemically modified α-cobratoxin (mToxin) to inhibit the interaction between Aβ and α7AChR. Subsequently, we examined mToxin in a set of original in silico, in vitro, ex vivo experiments, and in a murine AD model. We report that mToxin reversibly inhibits α7AChR, though it attenuates Aβ-induced synaptic transmission abnormalities, and upregulates pathways supporting long-term potentiation and reducing apoptosis. Remarkably, mToxin demonstrates no toxicity in brain slices and mice. Moreover, its chronic intracerebroventricular administration improves memory in AD-model animals. Our results point to unique mToxin neuroprotective properties, which might be tailored for the treatment of AD. Our methodology bridges the gaps in understanding Aβ-α7AChR interaction and represents a promising direction for further investigations and clinical development.

Biocomputational Screening of Natural Compounds against Acetylcholinesterase

Alzheimer's disease (AD) is the most common form of dementia and is characterized by irreversible and progressive neurodegeneration. Cholinergic dysfunction has been reported in AD, and several cholinesterase inhibitors, including natural compounds and synthetic analogs, have been developed to treat the disease. However, there is currently no treatment for AD, as most drug-like compounds have failed in clinical trials. Acetylcholinesterase (AChE) is the target of most drugs used commercially to treat AD. This work focused on screening natural compounds obtained from the ZINC database (224, 205 compounds) against AChE to identify those possibly capable of enabling the management of AD. Indirubin and dehydroevodiamine were the best potential AChE inhibitors with free binding energies of -10.03 and -9.00 kcal/mol, respectively. The key residue (His447) of the active site of AChE was found to participate in complex interactions with these two molecules. Six H-bonds were involved in the 'indirubin-AChE' interaction and three H-bonds in the 'dehydroevodiamine-AChE' interaction. These compounds were predicted to cross the blood-brain barrier (BBB) and to exhibit high levels of intestinal absorption. Furthermore, 'indirubin-AChE' and 'dehydroevodiamine-AChE' complexes were found to be stable, as determined by root mean square deviation (RMSD) during a 50 ns molecular dynamics simulation study. Based on the free binding energies and stabilities obtained by simulation studies, we recommend that experimental studies be undertaken on indirubin and dehydroevodiamine with a view towards their potential use as treatments for AD.

Screening for Core Genes Related to Pathogenesis of Alzheimer's Disease

Alzheimer’s disease (AD), a nervous system disease, lacks effective therapies at present. RNA expression is the basic way to regulate life activities, and identifying related characteristics in AD patients may aid the exploration of AD pathogenesis and treatment. This study developed a classifier that could accurately classify AD patients and healthy people, and then obtained 3 core genes that may be related to the pathogenesis of AD. To this end, RNA expression data of the middle temporal gyrus of AD patients were firstly downloaded from GEO database, and the data were then normalized using limma package following a supplementation of missing data by k-Nearest Neighbor (KNN) algorithm. Afterwards, the top 500 genes of the most feature importance were obtained through Max-Relevance and Min-Redundancy (mRMR) analysis, and based on these genes, a series of AD classifiers were constructed through Support Vector Machine (SVM), Random Forest (RF), and KNN algorithms. Then, the KNN classifier with the highest Matthews correlation coefficient (MCC) value composed of 14 genes in incremental feature selection (IFS) analysis was identified as the best AD classifier. As analyzed, the 14 genes played a pivotal role in determination of AD and may be core genes associated with the pathogenesis of AD. Finally, protein-protein interaction (PPI) network and Random Walk with Restart (RWR) analysis were applied to obtain core gene-associated genes, and key pathways related to AD were further analyzed. Overall, this study contributed to a deeper understanding of AD pathogenesis and provided theoretical guidance for related research and experiments.

Investigation of therapeutic potential of cerium oxide nanoparticles in Alzheimer's disease using transgenic Drosophila

In the current study, the therapeutic potential of cerium oxide nanoparticles (nCeO2) was investigated in a human tau (htau) model of Alzheimer's disease (AD), using Drosophila melanogaster as an in vivo model. nCeO2 synthesised via the hydroxide-mediated approach were characterised using Fourier transform infrared (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD) analyses and Raman spectroscopy. Characterisation studies confirmed the formation of pure cubic-structured nCeO2 and showed that the particles were spherically shaped, with an average size between 20 and 25 nm. The synthesised nCeO2 were then administered as part of the diet to transgenic Drosophila for one month, at 0.1 and 1 mM concentrations, and its effect on the biochemical levels of superoxide dismutase (SOD), acetylcholinesterase (AChE), and the climbing activity of flies were studied in a pan-neuronal model (elav; htau) of AD. Using an eye-specific model of htau expression (GMR; htau), the effect of nCeO2 on htau and autophagy-related (ATG) gene expression was also studied. Dietary administration of nCeO2 at a concentration of 1 mM restored the activity of SOD similar to that of control, but both concentrations of nCeO2 failed to modulate the level of AChE, and did not elicit any significant improvements in the climbing activity of elav; htau flies. Moreover, nCeO2 at a concentration of 1 mM significantly affected the climbing activity of elav; htau flies. nCeO2 also elicited a significant decrease in htau gene expression at both concentrations and increased the mRNA expression of key autophagy genes ATG1 and ATG18. The results therefore indicate that nCeO2 aids in replenishing the levels of SOD and tau clearance via the activation of autophagy.

Amyloid-Beta Induces Different Expression Pattern of Tissue Transglutaminase and Its Isoforms on Olfactory Ensheathing Cells: Modulatory Effect of Indicaxanthin

Herein, we assessed the effect of full native peptide of amyloid-beta (Aβ) (1-42) and its fragments (25-35 and 35-25) on tissue transglutaminase (TG2) and its isoforms (TG2-Long and TG2-Short) expression levels on olfactory ensheathing cells (OECs). Vimentin and glial fibrillary acid protein (GFAP) were also studied. The effect of the pre-treatment with indicaxanthin from Opuntia ficus-indica fruit on TG2 expression levels and its isoforms, cell viability, total reactive oxygen species (ROS), superoxide anion (O₂⁻), and apoptotic pathway activation was assessed. The levels of Nestin and cyclin D1 were also evaluated. Our findings highlight that OECs exposure to Aβ(1-42) and its fragments induced an increase in TG2 expression levels and a different expression pattern of its isoforms. Indicaxanthin pre-treatment reduced TG2 overexpression, modulating the expression of TG2 isoforms. It reduced total ROS and O₂⁻ production, GFAP and Vimentin levels, inhibiting apoptotic pathway activation. It also induced an increase in the Nestin and cyclin D1 expression levels. Our data demonstrated that indicaxanthin pre-treatment stimulated OECs self-renewal through the reparative activity played by TG2. They also suggest that Aβ might modify TG2 conformation in OECs and that indicaxanthin pre-treatment might modulate TG2 conformation, stimulating neural regeneration in Alzheimer’s disease.