Exposure to metal ions regulates mRNA levels of APP and BACE1 in PC12 cells: blockage by curcumin

Investigating the effects of Thymus vulgaris essential oil, Allium cepa extract, and their active compounds (thymol and quercetin) on expression profile of genes related to Alzheimer's disease in PC12 model cell

Thymus vulgaris and Allium cepa are plants with great medicinal importance. Thymol monoterpene and quercetin, which are present in these plants, have anti-Alzheimer's and antioxidant effects. The objectives of this research were investigating the effects of these compounds on the pathogenesis and progress of Alzheimer's disease in cells modeled by formaldehyde. MTT, flow cytometry, and RT-PCR were used to investigate the toxicity, survival rate and apoptosis of the cells, and the expression level of PP2A, GSK3, NMDAR, BACE1, and APP genes, respectively. Also, the total antioxidant capacity of the modeled cells was measured. The results showed that the two compounds as well as the plants extract and essential oil were able to increase the percentage of cell survival; among them, Thymus vulgaris essential oil had the greatest effect (93.55316 % in 48 h exposure). In addition, quercetin was able to reduce the rate of apoptosis in Alzheimer's cells (4.73 %) which was greater than the effects of other compounds. In general, the essential oil of Thymus vulgaris compared to thymol; and quercetin compared to Allium cepa extract showed more improving effects on the expression of genes involved in the disease. All four compounds increased the antioxidant capacity of the modeled cells compared to the control group, and these effects were almost equal between the compounds. According to the obtained results, both plants, especially Thymus vulgaris can be proposed as candidates to be included in the diet of Alzheimer's patients. In addition, polyphenols thymol and quercetin as derivates from the studied plants can be used in new drugs development for Alzheimer's disease, with greater safety than currently used drugs. These results are significant because most of the drug for Alzheimer's treatments such as cholinesterases (e.g. rivastigmine and donepezil) and memantine are chemically based and have many side effects.

Environmental Toxins and Alzheimer's Disease: a Comprehensive Analysis of Pathogenic Mechanisms and Therapeutic Modulation

Alzheimer's disease is a leading cause of mortality worldwide. Inorganic and organic hazards, susceptibility to harmful metals, pesticides, agrochemicals, and air pollution are major environmental concerns. As merely 5% of AD cases are directly inherited indicating that these environmental factors play a major role in disease development. Long-term exposure to environmental toxins is believed to progress neuropathology, which leads to the development of AD. Numerous in-vitro and in-vivo studies have suggested the harmful impact of environmental toxins at cellular and molecular level. Common mechanisms involved in the toxicity of these environmental pollutants include oxidative stress, neuroinflammation, mitochondrial dysfunction, abnormal tau, and APP processing. Increased expression of GSK-3β, BACE-1, TNF-α, and pro-apoptotic molecules like caspases is observed upon exposure to these environmental toxins. In addition, the expression of neurotrophins like BDNF and GAP-43 have been found to be reduced as a result of toxicity. Further, modulation of signaling pathways involving PARP-1, PGC-1α, and MAPK/ERK induced by toxins have been reported to contribute in AD pathogenesis. These pathways are a promising target for developing novel AD therapeutics. Drugs like epigallocatechin-gallate, neflamapimod, salsalate, dexmedetomidine, and atabecestat are in different phases of clinical trials targeting the pathways for possible treatment of AD. This review aims to culminate the correlation between environmental toxicants and AD development. We emphasized upon the signaling pathways involved in the progression of the disease and the therapeutics under clinical trial targeting the altered pathways for possible treatment of AD.

Insights Into the Role of Copper in Neurodegenerative Diseases and the Therapeutic Potential of Natural Compounds

Neurodegenerative diseases encompass a collection of neurological disorders originating from the progressive degeneration of neurons, resulting in the dysfunction of neurons. Unfortunately, effective therapeutic interventions for these diseases are presently lacking. Copper (Cu), a crucial trace element within the human body, assumes a pivotal role in various biological metabolic processes, including energy metabolism, antioxidant defense, and neurotransmission. These processes are vital for the sustenance, growth, and development of organisms. Mounting evidence suggests that disrupted copper homeostasis contributes to numerous age-related neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), Wilson's disease (WD), Menkes disease (MD), prion diseases, and multiple sclerosis (MS). This comprehensive review investigates the connection between the imbalance of copper homeostasis and neurodegenerative diseases, summarizing pertinent drugs and therapies that ameliorate neuropathological changes, motor deficits, and cognitive impairments in these conditions through the modulation of copper metabolism. These interventions include Metal-Protein Attenuating Compounds (MPACs), copper chelators, copper supplements, and zinc salts. Moreover, this review highlights the potential of active compounds derived from natural plant medicines to enhance neurodegenerative disease outcomes by regulating copper homeostasis. Among these compounds, polyphenols are particularly abundant. Consequently, this review holds significant implications for the future development of innovative drugs targeting the treatment of neurodegenerative diseases.

Isolation of Fucoxanthin from Sargassum oligocystum Montagne, 1845 Seaweed in Vietnam and Its Neuroprotective Activity

Fucoxanthin extracted and purified from Vietnamese Sargassum oligocystum Montagne, 1845 exhibits various biological activities. In this study, the ability of fucoxanthin to inhibit acetylcholinesterase (AChE), the antioxidant activities, and the expression of antioxidant enzymes were investigated. Fucoxanthin isolated from Vietnamese S. oligocystum showed no cytotoxic effects; moreover, it exhibited AChE inhibitory activity (with an IC50 value of 130.12 ± 6.65 μg mL-1) and antioxidant activity (with an IC50 value of 3.42 ± 0.15 mg mL-1). At concentrations of 50 and 100 µg mL-1, fucoxanthin provided protection against amyloid β-protein fragment 25-35-induced neurotoxicity in a C6 neuronal cell line, and the survival of C6 cells was higher than 81.01% and 80.98%, respectively, compared to the control group (59%). Moreover, antioxidant enzyme activity and quantitative PCR analysis suggested that the neuroprotective effect of fucoxanthin resulted from regulation of the gene expression of antioxidant enzymes (CAT and GPx) and ER pathways (caspase-3 and Bax), as well as the promotion of expression of genes involved in PI3K/Akt signaling (GSK-3β), autophagy (p62 and ATG5), and the biosynthesis of ACh (VAChT and ChAT). Therefore, fucoxanthin extracted from the seaweed S. oligocystum in Vietnam is a potential feedstock source for the production of health foods that exert neuroprotective effects.

Aluminum neurotoxicity and autophagy: a mechanistic view

It is strongly believed that aluminum is one of the insalubrious agents because of its neurotoxicity effects and influences on amyloid β (Aβ) production and tau protein hyperphosphorylation following oxidative stress, as one of the initial events in neurotoxicity. The autophagy process plays a considerable role in neurons in preserving intracellular homeostasis and recycling organelles and proteins, especially Aβ and soluble tau. Thus, autophagy is suggested to ameliorate aluminum neurotoxicity effects, and dysfunction of this process can lead to an increase in detrimental proteins. However, the relationship between aluminum neurotoxicity and autophagy dysregulation in some dimensions remains unclear. In the present review, we want to give an overview of the autophagy roles in aluminum neurotoxicity and how dysregulation of autophagy can affect aluminum neurotoxicity.

Aluminum alters excitability by inhibiting calcium, sodium, and potassium currents in bovine chromaffin cells

Aluminum (Al³⁺ ) has long been related to neurotoxicity and neurological diseases. This study aims to describe the specific actions of this metal on cellular excitability and neurotransmitter release in primary culture of bovine chromaffin cells. Using voltage-clamp and current-clamp recordings with the whole-cell configuration of the patch clamp technique, online measurement of catecholamine release, and measurements of [Ca²⁺ ]_c with Fluo-4-AM, we have observed that Al³⁺ reduced intracellular calcium concentrations around 25% and decreased catecholamine secretion in a dose-dependent manner, with an IC₅₀ of 89.1 μM. Al³⁺ blocked calcium currents in a time- and concentration-dependent manner with an IC₅₀ of 560 μM. This blockade was irreversible since it did not recover after washout. Moreover, Al³⁺ produced a bigger blockade on N-, P-, and Q-type calcium channels subtypes (69.5%) than on L-type channels subtypes (50.5%). Sodium currents were also inhibited by Al³⁺ in a time- and concentration-dependent manner, 24.3% blockade at the closest concentration to the IC₅₀ (399 μM). This inhibition was reversible. Voltage-dependent potassium currents were low affected by Al³⁺ . Nonetheless, calcium/voltage-dependent potassium currents were inhibited in a concentration-dependent manner, with an IC₅₀ of 447 μM. This inhibition was related to the depression of calcium influx through voltage-dependent calcium channels subtypes coupled to BK channels. In summary, the blockade of these ionic conductance altered cellular excitability that reduced the action potentials firing and so, the neurotransmitter release and the synaptic transmission. These findings prove that aluminum has neurotoxic properties because it alters neuronal excitability by inhibiting the sodium currents responsible for the generation and propagation of impulse nerve, the potassium current responsible for the termination of action potentials, and the calcium current responsible for the neurotransmitters release.

Current Naturopathy to Combat Alzheimer's Disease

Neurodegeneration is the progressive loss of structure or function of neurons, which may ultimately involve cell death. The most common neurodegenerative disorder in the brain happens with Alzheimer's disease (AD), the most common cause of dementia. It ultimately leads to neuronal death, thereby impairing the normal functionality of the central or peripheral nervous system. The onset and prevalence of AD involve heterogeneous etiology, either in terms of genetic predisposition, neurometabolomic malfunctioning, or lifestyle. The worldwide relevancies are estimated to be over 45 million people. The rapid increase in AD has led to a concomitant increase in the research work directed towards discovering a lucrative cure for AD. The neuropathology of AD comprises the deficiency in the availability of neurotransmitters and important neurotrophic factors in the brain, extracellular betaamyloid plaque depositions, and intracellular neurofibrillary tangles of hyperphosphorylated tau protein. Current pharmaceutical interventions utilizing synthetic drugs have manifested resistance and toxicity problems. This has led to the quest for new pharmacotherapeutic candidates naturally prevalent in phytochemicals. This review aims to provide an elaborative description of promising Phyto component entities having activities against various potential AD targets. Therefore, naturopathy may combine with synthetic chemotherapeutics to longer the survival of the patients.

In Vitro and In Vivo Neuroprotective Effects of Sarcosine

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by behavioral and psychological symptoms in addition to cognitive impairment and loss of memory. The exact pathogenesis and genetic background of AD are unclear and there remains no effective treatment option. Sarcosine, an n-methyl derivative of glycine, showed a promising therapeutic strategy for some cognitive disorders. To our knowledge, the impacts of sarcosine supplementation against AD have not yet been elucidated. Therefore, we aimed to determine the neuroprotective potential of sarcosine in in vitro and in vivo AD model. In vitro studies have demonstrated that sarcosine increased the percentage of viable cells against aluminum induced neurotoxicity. In AlCl₃-induced rat model of AD, the level of antioxidant capacity was significantly decreased and expression levels of APP, BACE1, TNF-α, APH1A, and PSENEN genes were elevated compared to the control group. Additionally, histopathological examinations of the hippocampus of AlCl₃-induced rat brains showed the presence of neurofibrillary tangles (NFTs). However, the administration of sarcosine produced marked improvement and protection of AD-associated pathologies induced by AlCl₃ in experimental rats. Therefore, this investigation may contribute to design novel therapeutic strategies using sarcosine for the management of AD pathologies.

Anti-Alzheimer's disease potential of traditional chinese medicinal herbs as inhibitors of BACE1 and AChE enzymes

Alzheimer's disease (AD) is a common neurodegenerative disease that often occurs in the elderly population. At present, most drugs for AD on the market are single-target drugs, which have achieved certain success in the treatment of AD. However, the efficacy and safety of single-target drugs have not achieved the expected results because AD is a multifactorial disease. Multi-targeted drugs act on multiple factors of the disease network to improve efficacy and reduce adverse reactions. Therefore, the search for effective dual-target or even multi-target drugs has become a new research trend. Many of results found that the dual-target inhibitors of the beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) and acetylcholinesterase (AChE) found from traditional Chinese medicine have a good inhibitory effect on AD with fewer side effects. This article reviews sixty-six compounds extracted from Chinese medicinal herbs, which have inhibitory activity on BACE1 and AChE. This provides a theoretical basis for the further development of these compounds as dual-target inhibitors for the treatment of AD.

Neuroprotective potential of curcuminoids in modulating Alzheimer's Disease via multiple signaling pathways

Alzheimer's disease (AD) is a progressive and frequent neurodegenerative disease of elderly people. In the 21st century, owing to the increasing prevalence of AD, there is a crucial need for finding better and effective pharmacotherapeutic approaches. This review article demonstrated the various sources and possible metabolic pathways of curcuminoids obtained from Curcuma longa herb, to prevent and treat AD but the information related to the metabolic fate of curcuminoids is deficient. Different in vitro and in vivo research studies demonstrating the mechanisms by which curcuminoids attenuated AD have been summarized. Administration of curcuminoids has been indicated to inhibit hyperphosphorylation of tau protein, deposition, and oligomerization of amyloid beta plaques in several AD models. Curcuminoids also chelate metals and form complexes, have antioxidant properties, mediates neuroinflammatory signaling pathways by modifying microglial cells activity, inhibit acetylcholinesterase activities and also modulates other associated signaling pathways including insulin signaling pathways and heme-oxygenase pathway. Briefly curcuminoids exhibit the capability to be more productive and efficacious compared to many recent treatments due to their antioxidant, delayed neuron degeneration and anti-inflammatory potential. Although their effectiveness as a curative agent is considered to be reduced due to their low bioavailability, If the issue of curcuminoids' low bioavailability is resolved then curcuminoid-based medications are hopefully on the horizon against AD.

Neurotoxic effects of aluminium exposure as a potential risk factor for Alzheimer's disease

Aluminium is one of the most widely distributed elements of the Earth's crust. Its routine use has resulted in excessive human exposure and due to the potential neurotoxic effects has attained a huge interest in recent years. Despite its ubiquitous abundance, aluminium has no crucial biological functions in the human body. Oxidative stress and neuroinflammatory effects are attributed to its neurotoxic manifestations implicated in Alzheimer's disease. In this review, we have discussed the neuroinflammatory and neurodegenerative events in the brain induced by aluminium exposure. We have highlighted the neurotoxic events caused by aluminium, such as oxidative stress, apoptosis, inflammatory events, calcium dyshomeostasis, Aβ deposition, and neurofibrillary tangle formation in the brain. In addition, the protective measures needed for prevention of aluminium-induced neuronal dysregulations have also been discussed.

The Interplay of the Unfolded Protein Response in Neurodegenerative Diseases: A Therapeutic Role of Curcumin

Abnormal accumulation of misfolded proteins in the endoplasmic reticulum and their aggregation causes inflammation and endoplasmic reticulum stress. This promotes accumulation of toxic proteins in the body tissues especially brain leading to manifestation of neurodegenerative diseases. The studies suggest that deregulation of proteostasis, particularly aberrant unfolded protein response (UPR) signaling, may be a common morbific process in the development of neurodegeneration. Curcumin, the mixture of low molecular weight polyphenolic compounds from turmeric, Curcuma longa has shown promising response to prevents many diseases including current global severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and neurodegenerative disorders. The UPR which correlates positively with neurodegenerative disorders were found affected by curcumin. In this review, we examine the evidence from many model systems illustrating how curcumin interacts with UPR and slows down the development of various neurodegenerative disorders (ND), e.g., Alzheimer's and Parkinson's diseases. The recent global increase in ND patients indicates that researchers and practitioners will need to develop a new pharmacological drug or treatment to manage and cure these neurodegenerative diseases.

Microglia and Astrocytes in Alzheimer's Disease in the Context of the Aberrant Copper Homeostasis Hypothesis

Evidence of copper's (Cu) involvement in Alzheimer's disease (AD) is available, but information on Cu involvement in microglia and astrocytes during the course of AD has yet to be structurally discussed. This review deals with this matter in an attempt to provide an updated discussion on the role of reactive glia challenged by excess labile Cu in a wide picture that embraces all the major processes identified as playing a role in toxicity induced by an imbalance of Cu in AD.

Trace element alterations in Alzheimer's disease: A review

Dyshomeostasis of trace elements have been implicated in the progression of Alzheimer's disease (AD), which is characterized by amyloid-β (Aβ) plaques. Trace elements are particularly associated with the Aβ plaques. Metal-protein attenuating compounds have been developed to inhibit metals from binding to Aβ proteins, which result in Aβ termination, in the hope of improving cognitive functioning. However, there are still some contradicting reports. This review aims to first establish which trace elements are increased or decreased in the brains of Alzheimer's patients, and secondly, to review the effectiveness of clinical trials with metal-protein attenuating compounds for AD. Studies have consistently reported unchanged or increased iron, contradicting reports for zinc, decreased copper, unchanged or decreased manganese, inconsistent results for calcium, and magnesium seems to be unaffected. However, varied results have been reported for all trace elements. Clinical trials using metal-protein attenuating compounds to treat AD have also reported varied results. Copper chelators have repeatedly been used in clinical trials, even though few studies report increased brain copper levels in AD patients. Homeostasis of copper levels is important since copper has a vital role in several enzymes, such as cytochrome c, Cu/Zn superoxide dismutase and ceruloplasmin. Dyshomeostasis of copper levels can lead to increased oxidative stress and neuronal loss. Future studies should assess a variety of trace element levels in moderately and severely affected AD patients since there are contradicting reports. This review thus provides some insight into trace element alterations in the brains of individuals with AD.

Environmental exposures and the etiopathogenesis of Alzheimer's disease: The potential role of BACE1 as a critical neurotoxic target

Alzheimer's disease (AD) is a major public health crisis due to devastating cognitive symptoms, a lack of curative treatments, and increasing prevalence. Most cases are sporadic (>95% of cases) after the age of 65 years, implicating an important role of environmental factors in disease pathogenesis. Environmental neurotoxicants have been implicated in neurodegenerative disorders including Parkinson's Disease and AD. Animal models of AD and in vitro studies have shed light on potential neuropathological mechanisms, yet the biochemical and molecular underpinnings of AD-relevant environmental neurotoxicity remain poorly understood. Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) is a potentially critical pathogenic target of environmentally induced neurotoxicity. BACE1 clearly has a critical role in AD pathophysiology: It is required for amyloid beta production and expression and activity of BACE1 are increased in the AD brain. Though the literature on BACE1 in response to environmental insults is limited, current studies, along with extensive AD neurobiology literature suggest that BACE1 deserves attention as an important neurotoxic target. Here, we critically review research on environmental neurotoxicants such as metals, pesticides, herbicides, fungicides, polyfluoroalkyl substances, heterocyclic aromatic amines, advanced glycation end products, and acrolein that modulate BACE1 and potential mechanisms of action. Though more research is needed to clearly understand whether BACE1 is a critical mediator of AD-relevant neurotoxicity, available reports provide convincing evidence that BACE1 is altered by environmental risk factors associated with AD pathology, implying that BACE1 inhibition and its use as a biomarker should be considered in AD management and research.

Neuroprotective Effects of D-(-)-Quinic Acid on Aluminum Chloride-Induced Dementia in Rats

OBJECTIVE

The present study was designed to evaluate the neuroprotective effects of D-(-)-quinic acid on aluminum chloride- (AlCl3-) induced neurobehavioral and biochemical changes in rats. This study showed the behavioral and biochemical effects of D-(-)-quinic acid on rats with particular emphasis on the hippocampus and frontal cortex which are associated with memory.

MATERIALS AND METHODS

Chronic administration of aluminum chloride at a dose of 175 mg/kg, p.o. for a period of 25 days markedly increased the level of acetylcholinesterase (AChE) activity and reduced the levels of antioxidant enzymes in the brain. Two doses of D-(-)-quinic acid (200 mg/kg and 400 mg/kg) were selected based on previous safety/toxicity studies and administered orally from the 26th day to the 36th day of the trial. Behavioral parameters were assessed using the Morris water maze test and an actophotometer in rats. Biochemical parameter content and histology of brain tissue were assessed on the final day of the experiment.

RESULTS

D-(-)-Quinic acid (200 mg/kg and 400 mg/kg) orally administered alongside AlCl3 rescued AChE activity and the behavioral impairments caused by aluminum. There was significant inhibition of MAO-B in D-(-)-quinic acid-treated rats. Histopathological studies in the hippocampus and cortex of the rat brain also supported that D-(-)-quinic acid markedly reduced the toxicity of AlCl3 and preserved the normal histoarchitecture pattern of the hippocampus and cortex. These results indicate that D-(-)-quinic acid can reverse memory loss caused by aluminum intoxication by attenuating AChE activity and rescuing the deleterious effect of AlCl3.

Mercury and Alzheimer's Disease: Hg(II) Ions Display Specific Binding to the Amyloid-β Peptide and Hinder Its Fibrillization

Brains and blood of Alzheimer's disease (AD) patients have shown elevated mercury concentrations, but potential involvement of mercury exposure in AD pathogenesis has not been studied at the molecular level. The pathological hallmark of AD brains is deposition of amyloid plaques, consisting mainly of amyloid-β (Aβ) peptides aggregated into amyloid fibrils. Aβ peptide fibrillization is known to be modulated by metal ions such as Cu(II) and Zn(II). Here, we study in vitro the interactions between Aβ peptides and Hg(II) ions by multiple biophysical techniques. Fluorescence spectroscopy and atomic force microscopy (AFM) show that Hg(II) ions have a concentration-dependent inhibiting effect on Aβ fibrillization: at a 1:1 Aβ·Hg(II) ratio only non-fibrillar Aβ aggregates are formed. NMR spectroscopy shows that Hg(II) ions interact with the N-terminal region of Aβ(1-40) with a micromolar affinity, likely via a binding mode similar to that for Cu(II) and Zn(II) ions, i.e., mainly via the histidine residues His6, His13, and His14. Thus, together with Cu(II), Fe(II), Mn(II), Pb(IV), and Zn(II) ions, Hg(II) belongs to a family of metal ions that display residue-specific binding interactions with Aβ peptides and modulate their aggregation processes.

Transferrin is responsible for mediating the effects of iron ions on the regulation of anterior pharynx-defective-1α/β and Presenilin 1 expression via PGE2 and PGD2 at the early stage of Alzheimer's Disease

Transferrin (Tf) is an important iron-binding protein postulated to play a key role in iron ion (Fe) absorption via the Tf receptor (TfR), which potentially contributes to the pathogenesis of Alzheimer’s disease (AD). However, the role of Tf in AD remains unknown. Using mouse-derived neurons and APP/PS1 transgenic (Tg) mice as model systems, we firstly revealed the mechanisms of APH-1α/1β and presenilin 1 (PS1) upregulation by Fe in prostaglandin (PG) E₂- and PGD₂-dependent mechanisms. Specifically, Fe stimulated the expression of mPGES-1 and the production of PGE₂ and PGD₂ via the Tf and TfR system. Highly accumulated PGE₂ markedly induced the expression of anterior pharynx-defective-1α and -1β (APH-1α/1β) and PS1 via an EP receptor-dependent mechanism. In contrast, PGD₂ suppressed the expression of APH-1α/1β and PS1 via a prostaglandin D₂ (DP) receptor-dependent mechanism. As the natural dehydrated product of PGD₂, 15d-PGJ₂ exerts inhibitory effects on the expression of APH-1α/1β and PS1 in a peroxisome proliferator-activated receptor (PPAR) γ-dependent manner. The expression of APH-1α/1β and PS1 ultimately determined the production and deposition of β-amyloid protein (Aβ), an effect that potentially contributes to the pathogenesis of AD.

Bioactive Food Abates Metabolic and Synaptic Alterations by Modulation of Gut Microbiota in a Mouse Model of Alzheimer's Disease

Recent investigations have demonstrated an important role of gut microbiota (GM) in the pathogenesis of Alzheimer's disease (AD). GM modulates a host's health and disease by production of several substances, including lipopolysaccharides (LPS) and short-chain fatty acids (SCFAs), among others. Diet can modify the composition and diversity of GM, and ingestion of a healthy diet has been suggested to lower the risk to develop AD. We have previously shown that bioactive food (BF) ingestion can abate neuroinflammation and oxidative stress and improve cognition in obese rats, effects associated with GM composition. Therefore, BF can impact the gut-brain axis and improved behavior. In this study, we aim to explore if inclusion of BF in the diet may impact central pathological markers of AD by modulation of the GM. Triple transgenic 3xTg-AD (TG) female mice were fed a combination of dried nopal, soy, chia oil, and turmeric for 7 months. We found that BF ingestion improved cognition and reduced Aβ aggregates and tau hyperphosphorylation. In addition, BF decreased MDA levels, astrocyte and microglial activation, PSD-95, synaptophysin, GluR1 and ARC protein levels in TG mice. Furthermore, TG mice fed BF showed increased levels of pGSK-3β. GM analysis revealed that pro-inflammatory bacteria were more abundant in TG mice compared to wild-type, while BF ingestion was able to restore the GM's composition, LPS, and propionate levels to control values. Therefore, the neuroprotective effects of BF may be mediated, in part, by modulation of GM and the release of neurotoxic substances that alter brain function.

Effects of in vivo conditions on amyloid aggregation

One of the grand challenges of biophysical chemistry is to understand the principles that govern protein misfolding and aggregation, which is a highly complex process that is sensitive to initial conditions, operates on a huge range of length- and timescales, and has products that range from protein dimers to macroscopic amyloid fibrils. Aberrant aggregation is associated with more than 25 diseases, which include Alzheimer's, Parkinson's, Huntington's, and type II diabetes. Amyloid aggregation has been extensively studied in the test tube, therefore under conditions that are far from physiological relevance. Hence, there is dire need to extend these investigations to in vivo conditions where amyloid formation is affected by a myriad of biochemical interactions. As a hallmark of neurodegenerative diseases, these interactions need to be understood in detail to develop novel therapeutic interventions, as millions of people globally suffer from neurodegenerative disorders and type II diabetes. The aim of this review is to document the progress in the research on amyloid formation from a physicochemical perspective with a special focus on the physiological factors influencing the aggregation of the amyloid-β peptide, the islet amyloid polypeptide, α-synuclein, and the hungingtin protein.

Natural Compounds for Alzheimer's Disease Therapy: A Systematic Review of Preclinical and Clinical Studies

Alzheimer's Disease (AD) is a neurodegenerative disorder related with the increase of age and it is the main cause of dementia in the world. AD affects cognitive functions, such as memory, with an intensity that leads to several functional losses. The continuous increase of AD incidence demands for an urgent development of effective therapeutic strategies. Despite the extensive research on this disease, only a few drugs able to delay the progression of the disease are currently available. In the last years, several compounds with pharmacological activities isolated from plants, animals and microorganisms, revealed to have beneficial effects for the treatment of AD, targeting different pathological mechanisms. Thus, a wide range of natural compounds may play a relevant role in the prevention of AD and have proven to be efficient in different preclinical and clinical studies. This work aims to review the natural compounds that until this date were described as having significant benefits for this neurological disease, focusing on studies that present clinical trials.

The impact of curcumin and its modified formulations on Alzheimer's disease

Alzheimer's disease (AD) is a major health problem worldwide, with no effective treatment approach. Curcumin is the main ingredient of turmeric traditionally used in Asian medicine. Several experimental studies have indicated the protective effect of curcumin and its novel formulations in AD. Curcumin has antioxidant, anti-inflammatory and neurotrophic activities, proposing a strong potential to prevent neurodegenerative diseases. However, there are no sufficient clinical trials to confirm curcumin use in AD patients. Low bioavailability following oral administration of curcumin limits its usage in human. The present study was designed to gather the effects of curcumin and its modified formulations in human and experimental models of AD.

Metal Toxicity Links to Alzheimer's Disease and Neuroinflammation

As the median age of the population increases, the number of individuals with Alzheimer's disease (AD) and the associated socio-economic burden are predicted to worsen. While aging and inherent genetic predisposition play major roles in the onset of AD, lifestyle, physical fitness, medical condition, and social environment have emerged as relevant disease modifiers. These environmental risk factors can play a key role in accelerating or decelerating disease onset and progression. Among known environmental risk factors, chronic exposure to various metals has become more common among the public as the aggressive pace of anthropogenic activities releases excess amount of metals into the environment. As a result, we are exposed not only to essential metals, such as iron, copper, zinc and manganese, but also to toxic metals including lead, aluminum, and cadmium, which perturb metal homeostasis at the cellular and organismal levels. Herein, we review how these metals affect brain physiology and immunity, as well as their roles in the accumulation of toxic AD proteinaceous species (i.e., β-amyloid and tau). We also discuss studies that validate the disruption of immune-related pathways as an important mechanism of toxicity by which metals can contribute to AD. Our goal is to increase the awareness of metals as players in the onset and progression of AD.

Reduction of aluminum ion neurotoxicity through a small peptide application - NAP treatment of Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia in late life. It is difficult to precisely diagnose AD at early stages, making biomarker search essential for further developments. The objective of this study was to identify protein biomarkers associated with aluminum ions toxicity (AD-like toxicity) in a human neuroblastoma cell model, SH-SY5Y and assess potential prevention by NAP (NAPVSIPQ). Complete proteomic techniques were implemented. Four proteins were identified as up-regulated with aluminum ion treatment, CBP80/20-dependent translation initiation factor (CTIF), Early endosome antigen 1 (EEA1), Leucine-rich repeat neuronal protein 4 (LRRN4) and Phosphatidylinositol 3-kinase regulatory subunit beta (PI3KR2). Of these four proteins, EEA1 and PI3KR2 were down-regulated after NAP-induced neuroprotective activity in neuroblastoma cells. Thus, aluminum ions may increase the risk for neurotoxicity in AD, and the use of NAP is suggested as a treatment to provide additional protection against the effects of aluminum ions, via EEA1 and PI3KR2, associated with sorting and processing of the AD amyloid precursor protein (APP) through the endosomal system.

Evaluation of neuroprotective effects of wedelolactone and gallic acid on aluminium-induced neurodegeneration: Relevance to sporadic amyotrophic lateral sclerosis

Al exposure causes an alteration in the several ions in the body and causes toxicity. Such as apoptosis, oxidative stress, disruption in neuronal transport, mitochondrial damage, excitotoxicity, generation of inflammatory mediators, and microglial activation. These multiple mechanisms lead to the several neurodegenerative diseases, including sporadic amyotrophic lateral sclerosis (sALS). The study aims to unravel the mechanisms behind the neuroprotective effects of wedelolactone (WL) and gallic acid (GA) against aluminium-induced neurodegeneration and thereby to unlock a platform to find a cure for sALS. We studied the neuroprotective effects of WL (100 & 200 mg/kg) and GA (100 & 200 mg/kg) using aluminium chloride (AlCl₃)-induced neurodegeneration model. The study was conducted using male Wistar rats. We assessed the effects of WL and GA on motor learning ability, motor coordination, locomotor activity, cytokine production, BDNF, glutathione peroxidase (GPx), m-calpain, caspase-3 inhibition and L-glutamate level. The study suggests that the treatment with WL and GA could protect the motor neurons from the toxicity that caused by Al via improving the antioxidant status, BDNF, and by preventing glutamate excitotoxicity. Also, WL and GA are found to be effective in inhibiting caspase-3 activation and downregulating inflammatory cytokines. WL and GA also found effective in improving the motor learning abilities and motor coordination in rats. The protective effects of the WL and GA were further confirmed from histopathological results. WL and GA prevent the neurofibrillary tangle formation and neuronal damage. The study concluded that the WL and GA were dose-dependently effective in managing the AlCl₃-induced neurodegeneration.

Is aluminum exposure a risk factor for neurological disorders?

Aluminum (Al) is widely found in the nature. Although the relation between Al and neurodegenerative diseases is still controversial, Al is related with many brain diseases including Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Al exposure occurs mainly through environment, occupational, and dietary factors for humans. Al exposure with diet can be through foods, food additives, water, and contamination of Al equipment/utensils. The aim of this review is to summarize various hypotheses, which link Al and neurodegeneration, and to determine the roles of Al exposure through different sources including diet, environment, and occupation. Future studies should be done in vulnerable subgroups of population including children, patients receiving antacid or Al-containing pharmeteucials on a daily basis, patients with reduced renal function, and patients on parenteral nutrition regimens that are likely to be affected by possible adverse health effects of Al. In addition, gender, age, and Al interactions need to be determined. One of the most important challanges in future epidemiological studies is to determine which variables should be controlled. In addition, experimental studies should be more focused and translational. In this context, exposure dose, dose-response effects, and time lapse between exposures and cognitive assessments are very important.

The Mechanisms of Action of Curcumin in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder of the elderly. As the prevalence of AD rises in the 21st century, there is an urgent need for the development of effective pharmacotherapies. Currently, drug treatments target the symptoms of the disease and do not modify or halt the disease progress. Thus, natural compounds have been investigated for their ability to treat AD. This review examines the efficacy of curcumin, a polyphenol derived from turmeric herb, to treat AD. We summarize the in vivo and in vitro research describing the mechanisms of action in which curcumin modifies AD pathology: curcumin inhibits the formation and promotes the disaggregation of amyloid-β plaques, attenuates the hyperphosphorylation of tau and enhances its clearance, binds copper, lowers cholesterol, modifies microglial activity, inhibits acetylcholinesterase, mediates the insulin signaling pathway, and is an antioxidant. In conclusion, curcumin has the potential to be more efficacious than current treatments. However, its usefulness as a therapeutic agent may be hindered by its low bioavailability. If the challenge of low bioavailability is overcome, curcumin-based medications for AD may be in the horizon.

Presenting a New Standard Drug Model for Turmeric and Its Prized Extract, Curcumin

Various parts of the turmeric plant have been used as medicinal treatment for various conditions from ulcers and arthritis to cardiovascular disease and neuroinflammation. The rhizome's curcumin extract is the most studied active constituent, which exhibits an expansive polypharmacology with influence on many key inflammatory markers. Despite the expansive reports of curcucmin's therapeutic value, clinical reliability and research repeatability with curcumin treatment are still poor. The pharmacology must be better understood and reliably mapped if curcumin is to be accepted and used in modern medical applications. Although the polypharmacology of this extract has been considered, in mainstream medicine, to be a drawback, a perspective change reveals a comprehensive and even synergistic shaping of the NF-kB pathway, including transactivation. Much of the inconsistent research data and unreliable clinical outcomes may be due to a lack of standardization which also pervades research standard samples. The possibility of other well-known curcumin by-products contributing in the polypharmacology is also discussed. A new flowchart of crosstalk in transduction pathways that lead to shaping of nuclear NF-kB transactivation is generated and a new calibration or standardization protocol for the extract is proposed which could lead to more consistent data extraction and improved reliability in therapy.

Curcumin Exerts Effects on the Pathophysiology of Alzheimer's Disease by Regulating PI(3,5)P2 and Transient Receptor Potential Mucolipin-1 Expression

Background

To validate our speculation that curcumin may ameliorate Alzheimer’s disease (AD) pathogenesis by regulating PI(3,5)P2 and transient receptor potential mucolipin-1 (TRPML1) expression levels.

Methods

We developed an animal model presenting AD by APP/PS1 transgenes. The mouse clonal hippocampal neuronal cell line HT-22 was treated with amyloid-β1-42 (Aβ1-42). Curcumin was administrated both in vivo and in vitro. MTS assay was used to detect cell viability, and the lysosomal [Ca²⁺] ion concentration was detected. The number of autophagosomes was detected by the transmission electron microscopic examination. Illumina RNA-seq was used to analyze the different expression patterns between Aβ1-42-treated cells without and with curcumin treatment. The protein level was analyzed by the Western blotting analysis. PI(3,5)P2 or TRPML1 was knocked down in HT-22 cells or in APP/PS1 transgenic mice. Morris water maze and recognition task were performed to trace the cognitive ability.

Results

Curcumin increased cell viability, decreased the number of autophagosomes, and increased lysosomal Ca²⁺ levels in Aβ1-42-treated HT-22 cells. Sequencing analysis identified TRPLML1 as the most significantly upregulated gene after curcumin treatment. Western blotting results also showed that TRPML1 was upregulated and mTOR/S6K signaling pathway was activated and markers of the autophagy–lysosomal system were downregulated after curcumin use in Aβ1-42-treated HT-22 cells. Knockdown of PI (3,5)P2 or TRPML1 increased the protein levels of markers of the autophagy–lysosomal system after curcumin use in Aβ1-42-treated HT-22 cells, inhibited mTOR/S6K signaling pathway, increased the protein levels of markers of the autophagy–lysosomal system after curcumin use in APP/PS1 mice. Besides, knockdown of PI(3,5)P2 or TRPML1 reversed the protective role of curcumin on memory and recognition impairments in mice with APP/PS1 transgenes.

Conclusion

To some extent, it suggested that the effects of curcumin on AD pathogenesis were, at least partially, associated with PI(3,5)P2 and TRPML1 expression levels.

Characterization of Mn(II) ion binding to the amyloid-β peptide in Alzheimer's disease

Growing evidence links neurodegenerative diseases to metal exposure. Aberrant metal ion concentrations have been noted in Alzheimer's disease (AD) brains, yet the role of metals in AD pathogenesis remains unresolved. A major factor in AD pathogenesis is considered to be aggregation of and amyloid formation by amyloid-β (Aβ) peptides. Previous studies have shown that Aβ displays specific binding to Cu(II) and Zn(II) ions, and such binding has been shown to modulate Aβ aggregation. Here, we use nuclear magnetic resonance (NMR) spectroscopy to show that Mn(II) ions also bind to the N-terminal part of the Aβ(1-40) peptide, with a weak binding affinity in the milli- to micromolar range. Circular dichroism (CD) spectroscopy, solid state atomic force microscopy (AFM), fluorescence spectroscopy, and molecular modeling suggest that the weak binding of Mn(II) to Aβ may not have a large effect on the peptide's aggregation into amyloid fibrils. However, identification of an additional metal ion displaying Aβ binding reveals more complex AD metal chemistry than has been previously considered in the literature.

Multifaceted effects of aluminium in neurodegenerative diseases: A review

Aluminium (Al) is the most common metal and widely distributed in our environment. Al was first isolated as an element in 1827, and its use began only after 1886. Al is widely used for industrial applications and consumer products. Apart from these it is also used in cooking utensils and in pharmacological agents, including antacids and antiperspirants from which the element usually enters into the human body. Evidence for the neurotoxicity of Al is described in various studies, but still the exact mechanism of Al toxicity is not known. However, the evidence suggests that the Al can potentiate oxidative stress and inflammatory events and finally leads to cell death. Al is considered as a well-established neurotoxin and have a link between the exposure and development of neurodegenerative diseases, including Amyotrophic Lateral Sclerosis (ALS), Alzheimer's disease (AD), dementia, Gulf war syndrome and Parkinsonism. Here, we review the detailed possible pathogenesis of Al neurotoxicity. This review summarizes Al induced events likewise oxidative stress, cell mediated toxicity, apoptosis, inflammatory events in the brain, glutamate toxicity, effects on calcium homeostasis, gene expression and Al induced Neurofibrillary tangle (NFT) formation. Apart from these we also discussed animal models that are commonly used for Al induced neurotoxicity and neurodegeneration studies. These models help to find out a better way to treat and prevent the progression in Al induced neurodegenerative diseases.

Suppressing the cytotoxicity of CuO nanoparticles by uptake of curcumin/BSA particles

The adverse effects of metal-based nanoparticles on human beings and the environment have received extensive attention recently. It is urgently required to develop a simple and effective method to suppress the toxicity of metal-based nanomaterials. In this study, a hydrophobic antioxidant and a chelation agent curcumin (CUR) were encapsulated into bovine serum albumin (BSA) particles by a simple co-precipitation method, and followed by glutaraldehyde cross-linking. The CUR/BSA particles had an average size of 300 nm in diameter with a negatively charged surface and sustained curcumin release properties. The cellular uptake and cytotoxicity of CUR/BSA particles were followed on A549 cells, HepG2 cells and RAW264.7 cells. The CUR/BSA particles had higher intracellular accumulation and lower cytotoxicity compared with the free curcumin at the same drug concentration. The CUR/BSA particles could suppress the cytotoxicity generated by CuO nanoparticles as a result of decrease of both the intracellular reactive oxygen species (ROS) level and Cu(2+) concentration, while the free curcumin did not show any obvious detoxicating effect. The detoxicating effects of CUR/BSA particles were further studied in an intratracheal instillation model in vivo, demonstrating significant reduction of toxicity and inflammatory response in rat lungs induced by CuO nanoparticles. The concept-proving study demonstrates the potential of the CUR/BSA particles in suppressing cytotoxicity of metal-based nanomaterials, which is a paramount requirement for the safe application of nanotechnology.

MEF2D Mediates the Neuroprotective Effect of Methylene Blue Against Glutamate-Induced Oxidative Damage in HT22 Hippocampal Cells

Methylene blue (MB) can ameliorate behavioral, neurochemical, and neuropathological impairments in animal models of acute and chronic neurodegenerative disorders, but the underlying mechanism remains unclear. Myocyte enhancer factor 2 (MEF2D) is known to promote neuronal survival in several models, and several survival and death signals converge on MEF2D and regulate its activity. Here, we investigated the role of MEF2D in the neuroprotective effect of MB against glutamate-induced toxicity in HT22 neuronal cells. Our results showed that MB, event at less than 100 nM, improved the viability of HT22 cells exposed to 2 mM glutamate. MB attenuated the mitochondrial impairment and quenches the reactive oxygen species (ROS) induced by glutamate. Surprisingly, MB at 50-200 nM did not affect the Nrf2/HO-1 pathway, an important endogenous anti-oxidative system. Further study showed that MB increased the transcription and translation of MEF2D. In addition, MB upregulated the expression of mitochondrial NADH dehydrogenase 6 (ND6) in a MEF2D-dependent manner. Knockdown of MEF2D abolished both MB-medicated increase of ND6 and MB-induced neuroprotection against glutamate-induced toxicity. Moreover, we showed that MB promoted Akt function activity, suppressed GSK-3β activity, and increased MEF2D level in hippocampus of mice and HT22 cells. These findings for the first time demonstrate that MB protects HT22 neuronal cells against glutamate-induced cell death partially via the regulation of MEF2D-associated survival pathway.

Clinical development of curcumin in neurodegenerative disease

Curcumin, a polyphenolic antioxidant derived from the turmeric root has undergone extensive preclinical development, showing remarkable efficacy in wound repair, cancer and inflammatory disorders. This review addresses the rationale for its use in neurodegenerative disease, particularly Alzheimer's disease. Curcumin is a pleiotropic molecule, which not only directly binds to and limits aggregation of the β-sheet conformations of amyloid characteristic of many neurodegenerative diseases but also restores homeostasis of the inflammatory system, boosts the heat shock system to enhance clearance of toxic aggregates, scavenges free radicals, chelates iron and induces anti-oxidant response elements. Although curcumin corrects dysregulation of multiple pathways, it may exert many effects via a few molecular targets. Pharmaceutical development of natural compounds like curcumin and synthetic derivatives have strong scientific rationale, but will require overcoming various hurdles including; high cost of trials, concern about profitability and misconceptions about drug specificity, stability, and bioavailability.

The Emerging Role of Metalloproteomics in Alzheimer's Disease Research

Metals are increasingly recognized to have an important role in molecular processes underlying Alzheimer's disease (AD). This chapter discusses the current role of metals in AD and expands on the development of metalloproteomics and how the recent advances in analytical technology will allow detailed investigation of metalloproteins. Investigation of individual metalloproteins will yield new mechanistic details about the role of metals in AD.

Nanoscale topography, semiconductor polarity and surface functionalization: additive and cooperative effects on PC12 cell behavior

This work compares the behavior of PC12 cells on planar and patterned III-nitride materials with nanostructured topographies.

Dietary Polyphenols as Potential Remedy for Dementia

With increasing life expectancy as a result of better quality of life and improved health care, the incidence of aging related diseases and disorders is heading toward epidemic proportions. Dementia, a spectrum of neurological diseases associated with aging, is an increasingly prevalent disease. No cure exists yet for dementia; however, there are many potential candidates for treatment of dementia that merit more exploration. Polyphenols, which constitute one such class of compounds, are dietary agents that are globally found in commonly consumed food. Many processes that are associated with the pathophysiology of dementia can be modulated by polyphenols. Polyphenolic compounds can alleviate oxidative stress by acting as direct scavengers of free radicals and clearing superoxide and hydroxyl radicals and by increasing the level of antioxidant enzymes such as glutathione peroxidase. They also chelate metal ions to prevent free radical formation. Polyphenols can also combat inflammation by affecting transcription factors such as NF-κB. Some polyphenols may have the potential to inhibit excitotoxicity by regulating intracellular calcium ion concentration, inhibiting glutamate receptors and increasing glutamate reuptake at the synapse. The cognitive decline in dementia due to decreased availability of acetylcholine can also be countered by polyphenols that inhibit acetyl-cholinesterase activity. Taken together, these findings suggest that increasing the consumption of polyphenol rich food may alleviate the effects of dementia. Moreover, their effects on controlling multiple mechanisms that are associated with dementia may also prevent or slow down the onset and progress of this devastating disease.

Examining the potential clinical value of curcumin in the prevention and diagnosis of Alzheimer’s disease

Curcumin derived from turmeric is well documented for its anti-carcinogenic, antioxidant and anti-inflammatory properties. Recent studies show that curcumin also possesses neuroprotective and cognitive-enhancing properties that may help delay or prevent neurodegenerative diseases, including Alzheimer’s disease (AD). Currently, clinical diagnosis of AD is onerous, and it is primarily based on the exclusion of other causes of dementia. In addition, phase III clinical trials of potential treatments have mostly failed, leaving disease-modifying interventions elusive. AD can be characterised neuropathologically by the deposition of extracellular β amyloid (Aβ) plaques and intracellular accumulation of tau-containing neurofibrillary tangles. Disruptions in Aβ metabolism/clearance contribute to AD pathogenesis. In vitro studies have shown that Aβ metabolism is altered by curcumin, and animal studies report that curcumin may influence brain function and the development of dementia, because of its antioxidant and anti-inflammatory properties, as well as its ability to influence Aβ metabolism. However, clinical studies of curcumin have revealed limited effects to date, most likely because of curcumin’s relatively low solubility and bioavailability, and because of selection of cohorts with diagnosed AD, in whom there is already major neuropathology. However, the fresh approach of targeting early AD pathology (by treating healthy, pre-clinical and mild cognitive impairment-stage cohorts) combined with new curcumin formulations that increase bioavailability is renewing optimism concerning curcumin-based therapy. The aim of this paper is to review the current evidence supporting an association between curcumin and modulation of AD pathology, including in vitro and in vivo studies. We also review the use of curcumin in emerging retinal imaging technology, as a fluorochrome for AD diagnostics.

Analysis of ERK3 intracellular localization: dynamic distribution during mitosis and apoptosis

Extracellular signal-regulated kinases (ERK) 1, 2 and 3 are involved in cell proliferation and differentiation, and apoptosis; although ERK1/2 have been widely studied, limited knowledge on ERK3 is available. The present work aimed at investigating ERK3 distribution during cell cycle and apoptosis in human tumor HeLa cells. The analysis performed by double immunofluorescence and immunoelectron microscopy revealed that during interphase ERK3 is mainly resident in the nucleoplasm in association with ribonuclear proteins involved in early pre-mRNA splicing, it undergoes cell cycle-dependent redistribution and, during apoptosis, it remains in the nucleus in the form of massive nuclear aggregates, then moves to the cytoplasm and is finally extruded.

Neuroprotective effect of hesperidin on aluminium chloride induced Alzheimer's disease in Wistar rats

The present study was aimed to evaluate the protective effect of hesperidin (Hes) on aluminium chloride (AlCl3) induced neurobehavioral and pathological changes in Alzheimeric rats. Intraperitonial injection of AlCl3 (100 mg/kg body weight) for 60 days significantly elevated the levels of aluminium (Al), activity of acetylcholinesterase (AChE) and protein expressions of amyloid precursor protein (APP), β amyloid (Aβ 1-42), β and γ secretases as compared to control group in hippocampus and cortex of rat brain. Hes administration orally along with AlCl3 injection for 60 days, significantly revert the Al concentration, AChE activity and Aβ synthesis-related molecules in the studied brain regions. Our results showed that aluminum exposure was significantly reduced the spontaneous locomotor and exploratory activities in open field test and enhanced the learning and memory impairments in morris water maze test. The behavioral impairments caused by aluminum were significantly attenuated by Hes. The histopathological studies in the hippocampus and cortex of rat brain also supported that Hes (100 mg/kg) markedly reduced the toxicity of AlCl3 and preserved the normal histoarchitecture pattern of the hippocampus and cortex. From these results, it is concluded that hesperidin can reverse memory loss caused by aluminum intoxication through attenuating AChE activity and amyloidogenic pathway.

Modulatory role of simvastatin against aluminium chloride-induced behavioural and biochemical changes in rats

Objectives. Aluminium, a neurotoxic agent in humans, has been implicated in the pathogenesis of neurodegenerative disorders. In this study, we examined the behavioral and biochemical effects of aluminium in rats with special emphasis on memory centres, namely, hippocampus and frontal cortex. Further, the effect of simvastatin treatment on aluminium intoxication was evaluated. Methods. Rats were exposed to aluminium chloride (AlCl₃) for 60 days. Simvastatin (10 mg/kg/p.o.) and rivastigmine (1 mg/kg/p.o.) were administered daily prior to AlCl₃. Behavioral parameters were assessed using Morris water maze test and actophotometer followed by biochemical investigations, namely, acetylcholinesterase (AChE) activity, TNF-α level, antioxidant enzymes (GSH, catalase), lipid peroxidation, and nitrite level in hippocampus and frontal cortex. Triglycerides, total cholesterol, LDL, and HDL levels in serum were also determined. Key Findings. Simvastatin treatment improved cognitive function and locomotor activity in rats. Simvastatin reversed hyperlipidemia and significantly rectified the deleterious effect of AlCl₃ on AChE activity. Further, in hippocampus and frontal cortex, aluminium-induced elevation in nitrite and TNF-α and reduction in antioxidant enzymes were inhibited by simvastatin. Conclusion. To conclude, the present study suggests that simvastatin per se protects the neurons in hippocampus and frontal cortex from AlCl₃, an environmental toxin.

Effect of tacrine-3-caffeic acid, a novel multifunctional anti-Alzheimer's dimer, against oxidative-stress-induced cell death in HT22 hippocampal neurons: involvement of Nrf2/HO-1 pathway

AIMS

Oxidative stress (OS) plays an important role in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD). This study was designed to uncover the cellular and biochemical mechanisms underlying the neuroprotective effects of tacrine-3-caffeic acid (T3CA), a novel promising multifunctional anti-Alzheimer's dimer, against OS-induced neuronal death.

METHODS AND RESULTS

T3CA protected HT22 cells against high-concentration-glutamate-induced cell death in time- and concentration-dependent manners and potently attenuated glutamate-induced intracellular reactive oxygen species (ROS) production as well as mitochondrial membrane-potential (ΔΨ) disruption. Besides, T3CA significantly induced nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation and increased its transcriptional activity, which were demonstrated by Western blotting, immunofluorescence, and antioxidant response element (ARE)-luciferase reporter gene assay. Further studies showed that T3CA potently up-regulated heme oxygenase-1 (HO-1), an endogenous antioxidative enzyme and a downstream effector of Nrf2, at both mRNA and protein levels. The neuroprotective effects of T3CA were partially reversed by brusatol, which reduced protein level of Nrf2, or by inhibiting HO-1 with siRNA or ZnPP-IX, a specific inhibitor of HO-1.

CONCLUSIONS

Taken together, these results clearly demonstrate that T3CA protects neurons against OS-induced cell death partially through Nrf2/ARE/HO-1 signaling pathway, which further supports that T3CA might be a promising novel therapeutic agent for OS-associated diseases.

Mercury induced the Accumulation of Amyloid Beta (Aβ) in PC12 Cells: The Role of Production and Degradation of Aβ

Extracellular accumulation of amyloid beta protein (Aβ) plays a central role in Alzheimer’s disease (AD). Some metals, such as copper, lead, and aluminum can affect the Aβ accumulation in the brain. However, the effect of mercury on Aβ accumulation in the brain is not clear. Thus, this study was proposed to estimate whether mercury concentration affects Aβ accumulation in PC12 cells. We treated 10, 100, and 1000 nM HgCl₂ (Hg) or CH₃HgCl₂ (MeHg) for 48 hr in PC12 cells. After treatment, Aβ₄₀ in culture medium increased in a dose- and time-dependent manner. Hg and MeHg increased amyloid precursor protein (APP), which is related to Aβ production. Neprilysin (NEP) levels in PC12 cells were decreased by Hg and MeHg treatment. These results suggested that Hg induced Aβ accumulation through APP overproduction and reduction of NEP.

Curcumin as a therapeutic agent in dementia: a mini systematic review of human studies

Dementia is a leading health problem worldwide, with Alzheimer's disease (AD) representing up to 60% of all dementia cases. A growing interest has recently risen on the potential use of natural molecules in this condition. Curcumin is a polyphenolic compound traditionally used in Indian medicine. Several in vitro and in vivo studies have found a protective effect of curcumin in AD. In the present systematic review we aimed to evaluate the state-of-the-art of clinical trials of curcumin in AD. We retrieved three published studies, while there are several ongoing clinical trials. To date there is insufficient evidence to suggest the use of curcumin in dementia patients. Of note, short-term use of curcumin appears to be safe. Several reasons could be responsible for the discrepancy between in vitro and in vivo findings and human trials, such as low bioavailability and poor study design.