Trace amounts of copper induce neurotoxicity in the cholesterol-fed mice through apoptosis

Evaluation of the cognitive, physiological, and biomarker effects of heavy metal exposure in Wistar rats

Background and Aim

Individuals exposed to heavy metals are known to experience physiological and biochemical changes, which raise questions regarding possible health effects. In our earlier research, significant concentrations of vanadium (V), mercury (Hg), cadmium (Cd), and arsenic (As) were found in food and medical packaging materials. This study aimed to evaluate the cognitive, physiological, and biomarker effects of select heavy metal exposure in Wistar rats.

Materials and Methods

Over a 13-week period, five groups of rats (six rats per group, with both males and females) were assessed to study the effects of oral exposure to V, Hg, Cd, and As. The study focused on evaluating physiological, cognitive, and biochemical markers, with the results compared to those of a control group.

Results

Comparing all groups of rats treated with heavy metals, the study revealed significant deficits in learning and spatial orientation (water maze test); rats treated with V, Cd, and Hg showed signs of depression. Rats treated with As also showed signs of hyperactivity, which may indicate a connection to attention-deficit hyperactivity disorder (rat tail suspension test). The groups exposed to different heavy metals varied in their physiological (water and food intake, urine and feces output) and biochemical responses (enzyme-linked immunosorbent assay, prostate-specific antigen, T3, T4, thyroid-stimulating hormone, carcinoembryonic antigen, and blood glucose analysis), with Hg exhibiting the strongest impacts. Rats given Hg showed signs of hypothyroidism, such as increased food intake and weight gain.

Conclusion

This study clarifies the complex relationships between exposure to heavy metals and various biological systems, shedding light on their potential health impacts. The findings provide insight into the effects of heavy metals on neural and thyroid tissues, as well as their propensity to cause cellular dedifferentiation. However, the study has certain limitations, such as the relatively short duration of exposure and the use of only a few selected biomarkers. Future research should focus on long-term exposure studies, incorporate a broader range of biomarkers, and explore the underlying mechanisms at a molecular level to better understand the full spectrum of health risks associated with heavy metal exposure.

Mammalian Models in Alzheimer's Research: An Update

A form of dementia distinct from healthy cognitive aging, Alzheimer's disease (AD) is a complex multi-stage disease that currently afflicts over 50 million people worldwide. Unfortunately, previous therapeutic strategies developed from murine models emulating different aspects of AD pathogenesis were limited. Consequently, researchers are now developing models that express several aspects of pathogenesis that better reflect the clinical situation in humans. As such, this review seeks to provide insight regarding current applications of mammalian models in AD research by addressing recent developments and characterizations of prominent transgenic models and their contributions to pathogenesis as well as discuss the advantages, limitations, and application of emerging models that better capture genetic heterogeneity and mixed pathologies observed in the clinical situation.

Evaluation of oxidative stress-mediated cytotoxicity and genotoxicity of copper and flubendiamide: amelioration by antioxidants in vivo and in vitro

Present study was designed to evaluate toxic effects of copper (Cu) (@ 33 mg/kg b.wt.) and flubendimide (Flb) (@ 200 mg/kg b.wt.) alone and/or in combination on blood-biochemical indices, oxidative stress, and drug metabolizing enzymes (DMEs) in vivo in male Wistar rats following oral exposure continuously for 90 days and their immunotoxic (cyto-genotoxic and apoptotic) potential in vitro on thymocytes. In in vivo study, ameliorative potential of α-tocopherol was assessed, whereas α-tocopherol, curcumin, resveratrol, and catechin were evaluated for protective effect in vitro. Significantly (P < 0.05) increased AST activity and increment in total bilirubin, uric acid, creatinine, and BUN levels; however, reduction in total protein, GSH content, reduced activities of SOD and GST, and increased lipid peroxidation and GPx activity with severe degenerative changes in histopathological examination of liver and kidney in group of Cu and Flb were observed. Treatment with α-tocopherol improved biochemical variables, redox status, and histoarchitecture of liver and kidney tissues. Reduced hepatic CYP450, CYPb5, APH, UGT, and GST activities observed in both Cu and α-tocopherol alone and their combination groups, whereas significant increment in Flb alone, while α-tocopherol in combination with xenobiotics improved the activities of hepatic DMEs. Primary cell culture of thymocytes (106 cells/ml) exposed to Cu and Flb each @ 40 μM increased TUNEL+ve cells, micronuclei induction, DNA shearing, and comet formation establishes their apoptotic and genotoxic potential, whereas treatment with antioxidants showed concentration-dependent significant reduction and their order of potency on equimolar concentration (10 μM) basis is: curcumin > resveratrol > catechin = α-tocopherol.

Naked-eye chemosensor with high absolute fluorescence quantum yield for selective detection of Cu(II) and cell imaging

The regulation of copper in the human body is important for the prevention of several diseases. Therefore, a rhodamine B-based chemosensor 1 that demonstrates substantial affinity and selectivity was synthesized for the fluorescence imaging of copper(II). In the presence of Cu²⁺, the chemosensor underwent a color change from colorless to amaranth that was visible to the naked eye, and the fluorescence intensity did not change when excess EDTA was added to the solution. Furthermore, strong fluorescence was observed at 575 nm. The limit of detection was determined as 12.1 nM. The absolute fluorescence quantum yield was as high as 77 % and the stoichiometry between 1 and Cu²⁺ was determined to be 1:1 using a job plot. An analytical method was developed and successfully used to evaluate the sensor's ability for the fluorescence imaging of Cu²⁺ in HeLa tumor cells.

Pseudo toxicity abatement effect of norfloxacin and copper combined exposure on Caenorhabditis elegans

The coexistence of antibiotics and heavy metals may result in complex ecotoxicological effects on living organisms. In this work, the combined toxic effects of norfloxacin (NOR) and copper (Cu) on Caenorhabditis elegans (C. elegans) were investigated due to the highly possible co-pollution tendency. The results indicated that locomotion behaviors (frequency of head thrash and body bend) of C. elegans were more sensitive as the exposure time of NOR or Cu prolonged. Meanwhile, the physiological indexes (locomotion behaviors, body length) of C. elegans were more sensitive to the combined pollution that with lower Cu dosage (0.0125 μM), in prolonged exposure experiments. In addition, the toxic effects of NOR-Cu on physiological indexes of C. elegans seemed to be alleviated during prolonged exposure when Cu was 1.25 μM. Similarly, the ROS production and apoptosis level almost unchanged with the addition of NOR compared with Cu (1.25 μM) exposure groups, but both significantly higher than the control groups. Furthermore, compared with Cu (0.0125 μM and 1.25 μM) exposure experiments, the addition of NOR had resulted in the genetic expression decrease of hsp-16.1, hsp-16.2, hsp-16.48, and the oxidative stress in C. elegans seems to be alleviated. However, the significantly decreased of ape-1 and sod-3 expression indicated the disruption of ROS defense mechanism. The irregular change in ace-1 and ace-2 gene expressions in NOR-Cu (0.0125 μM) would result in the locomotion behaviors disorders of C. elegans, and this also explains why C. elegans are more sensitive to the combination of NOR and lower concentration of Cu.

Novel Quinoline-Based Thiazole Derivatives for Selective Detection of Fe3+, Fe2+, and Cu2+ Ions

New quinoline-based thiazole derivatives QPT and QBT were synthesized and characterized by various spectroscopic and single-crystal X-ray crystallographic studies. The metal-sensing properties of the probes were further examined by absorption and fluorescence spectrometry. The fluorescence intensity of QPT and QBT was remarkably quenched during the addition of Fe³⁺, Fe²⁺, and Cu²⁺ ions in THF/H₂O (1:1) at pH = 7.4 in HEPES buffer, while the addition of other metal ions did not affect the fluorescence intensity of the ligands. The detection ability of the probes QPT and QBT was further investigated by titration with various equivalents of metal ions, optimized pH ranges for detection, and reversibility with Na₂EDTA for biological applications.

Chronic copper exposure leads to hippocampus oxidative stress and impaired learning and memory in male and female rats

Environmental and occupational exposures to copper (Cu) play a pivotal role in the etiology of some neurological diseases and reduced cognitive functions. However, the precise mechanisms of its effects on cognitive function have not been yet thoroughly established. In our study, we aimed to investigate the behavior and neurochemical alterations in hippocampus of male and female rats, chronically exposed to copper chloride (CuCl2) and the possible involvement of oxidative stress. Twenty-four rats, for each gender, were divided into control and three test groups (n = 6), and were injected intraperitoneally with saline (0.9% NaCl) or CuCl2 (0.25 mg/kg, 0.5 mg/kg and 1 mg/kg) for 8 weeks. After the treatment period, Y-maze test was used for the evaluation of spatial working memory and the Morris Water Maze (MWM) to test the spatial learning and memory. Biochemical determination of oxidative stress levels in hippocampus was performed. The main results of the present work are working memory impairment in spatial Y-maze which induced by higher Cu intake (1 mg/kg) in male and female rats. Also, In the MWM test, the spatial learning and memory were significantly impaired in rats treated with Cu at dose of 1 mg/kg. Additionally, markers of oxidative stress such as catalase, superoxide dismutase, lipid peroxidation products and nitric oxide levels were significantly altered following Cu treatments. These data propose that compromised behavior following Cu exposure is associated with increase in oxidative stress.

Agricultural Use of Copper and Its Link to Alzheimer's Disease

Copper is an essential nutrient for plants, animals, and humans because it is an indispensable component of several essential proteins and either lack or excess are harmful to human health. Recent studies revealed that the breakdown of the regulation of copper homeostasis could be associated with Alzheimer's disease (AD), the most common form of dementia. Copper accumulation occurs in human aging and is thought to increase the risk of AD for individuals with a susceptibility to copper exposure. This review reports that one of the leading causes of copper accumulation in the environment and the human food chain is its use in agriculture as a plant protection product against numerous diseases, especially in organic production. In the past two decades, some countries and the EU have invested in research to reduce the reliance on copper. However, no single alternative able to replace copper has been identified. We suggest that agroecological approaches are urgently needed to design crop protection strategies based on the complementary actions of the wide variety of crop protection tools for disease control.

In vitro and in vivo effects of flubendiamide and copper on cyto-genotoxicity, oxidative stress and spleen histology of rats and its modulation by resveratrol, catechin, curcumin and α-tocopherol

BACKGROUND

Living organisms are frequently exposed to more than one xenobiotic at a time either by ingestion of contaminated food/fodder or due to house-hold practices, occupational hazards or through environment. These xenobiotics interact individually or in combination with biological systems and act as carcinogen or produce other toxic effects including reproductive and degenerative diseases. Present study was aimed to investigate the cyto-genotoxic effects of flubendiamide and copper and ameliorative potential of certain natural phyotconstituent antioxidants.

METHOD

In vitro cytogenotoxic effects were evaluated by employing battery of assays including Propidium iodide staining, Tunel assay, Micronuclei, DNA fragmentation and Comet assay on isolated splenocytes and their prevention by resveratrol (5 and 10 μM), catechin (10 and 20 μM), curcumin (5 and 10 μM) and α-tocopherol (5, 10 and 20 μM). In vivo study was also undertaken daily oral administration of flubendiamide (200 mg/kg) or copper (33 mg/kg) and both these in combination, and also all these concurrently with of α-tocopherol to Wistar rats for 90 days.

RESULTS

Flubendiamide and copper produced concentration-dependent cytotoxic effects on splenocytes and at median lethal concentrations, flubendiamide (40 μM) and copper (40 μM) respectively produced 71 and 81% nonviable cells, higher number of Tunel+ve apoptotic cells, 7.86 and 9.16% micronucleus and 22.90 and 29.59 comets/100 cells and DNA fragmentation. In vivo study revealed significant (P < 0.05) increase in level of lipid peroxidation (LPO) and decrease in glutathione peroxidase (GPx), glutathione-S-transferase (GST) and superoxide dismutase (SOD) activities in groups exposed to flubendiamide or copper alone or both these in combination. Histopathological examination of rat spleens revealed depletion of lymphoid tissue, separation of splenocytes and rarification in splenic parenchyma of xenobiotic(s) treated groups.

CONCLUSION

Flubendiamide and copper induce oxidative stress and produce cytogenotoxic effects along with histoarchitectural changes in spleen. All four tested natural antioxidants (resveratrol, catechin, curcumin and α-tocopherol) reduced flubendiamide and copper-induced cytotoxic effects in rat splenocytes. Rat splenocytes are very sensitive to flubendiamide and copper-induced cytogenotoxicity, therefore, these can be effectively employed for screening of compounds for their cytogenotoxic potential. α-tocopherol was effective in restoring alterations in oxidative stress biomarkers and preventing histoarchitectural lesions in spleen.

Diffusion spectrum imaging in white matter microstructure in subjects with type 2 diabetes

This study aimed to investigate the feasibility and clinical applicability of Diffusion Spectrum Imaging (DSI) for quantitative detection of white matter microstructural integrity. Twenty-seven patients with type 2 diabetes mellitus (T2DM; aged 60.6±7.6 years) and 21 healthy controls (HC; aged 56.1±7.8 years) underwent high-resolution T1-weighted imaging and DSI scanning. Cognitive function scores were obtained using such instruments as the Montreal Cognitive Assessment (MoCA). The fasting blood glucose, glycated hemoglobin, and total cholesterol (CHO) of T2DM were measured. The bilateral uncinate fasciculus and superior cingulum bundle were reconstructed by DSI tractography. Statistical analysis was performed using SPSS 21.0 software and P<0.05 was considered significant. Generalized fractional anisotropy (GFA) values were significantly decreased in the left uncinate fasciculus (t = −2.915, p = 0.005) and right superior cingulum bundle (t = −2.604, p = 0.012) in T2DM patients compared with the healthy controls (p<0.05). The MoCA (t = −3.339, p = 0.002) and CDT (t = −3.039, p = 0.004) scores of T2DM were significantly lower than those of healthy controls. Meanwhile, the GFA value of the right superior cingulum bundle was negatively associated with VFT score (r = −0.475, p = 0.012), and that of the right superior cingulum bundle was negatively associated with blood CHO level (r = −0.458, p = 0.016). DSI tractography is capable of evaluating the microstructural integrity of the white matter bundle in T2DM and is related to clinical cognitive scores and related biochemical indices; therefore, it can help to predict early white matter abnormalities in T2DM.

Cytoprotective effect of deferiprone against aluminum chloride-induced oxidative stress and apoptosis in lymphocytes

Aluminum (Al) is a toxic metal, and excessive Al accumulation causes immunosuppression. Deferiprone (DFP) is a well-known chelator and used in dialysis patients for removing Al from tissues. The present study aimed to investigate whether DFP treatment can attenuate immunotoxicity induced by aluminum chloride (AlCl3) in cultured lymphocytes. Lymphocytes were treated with 0 and 0.6 mmol/L AlCl3∙6H2O (pH 7.2) and/or 1.8 mmol/L DFP, respectively. Immune function of lymphocytes was assessed by T and B lymphocytes proliferation rates, T lymphocyte subpopulations and IL-2, IL-6 and TNF-α contents. In addition, lymphocyte damage was assessed by LDH activity, NO and MDA contents, NOS, SOD and GSH-Px activities, lymphocyte apoptosis index. These results showed that AlCl3 exposure reduced T and B lymphocyte proliferation rates, CD3+ and CD4+ T lymphocyte subpopulations, CD4+/CD8+ ratio, IL-2, IL-6 and TNF-α contents, SOD and GSH-Px activities, early and later lymphocyte apoptosis indexes while enhanced CD8+ T lymphocyte subpopulation, NO and MDA contents, LDH activity. DFP treatment attenuated the immunotoxicity of lymphocytes and reduced oxidative stress and lymphocyte apoptosis induced by AlCl3, indicating that DFP could protect lymphocytes against immunosuppression induced by AlCl3 through attenuating oxidative stress and apoptosis.

Neuroprotective Effects of the Methanol Extract of Kimchi, a Korean Fermented Vegetable Food, Mediated Via Suppression of Endoplasmic Reticulum Stress and Caspase Cascade Pathways in High-Cholesterol Diet-Fed Mice

Endoplasmic reticulum (ER) stress-related unfolded peptide accumulation is closely associated with the development of neurodegenerative diseases known as protein misfolding disorders. The antioxidative properties of kimchi, a traditional Korean fermented vegetable dish, have been well established. In this study, the neuroprotective effects of the kimchi methanol extract (KME) were examined in high-cholesterol diet (HCD)-fed mice. The animals were fed a HCD, with oral administration of either KME (KME group, 200 mg·kg bw^-1·day^-1, n = 10) or distilled water (Control group, n = 10) for 8 weeks. Compared with the levels in the control group, the reactive oxygen species, peroxynitrite, and lipid peroxidation levels in the brain were significantly decreased in the KME group (P < .05), whereas the glutathione level was increased (P < .05). In addition, the ER stress biomarkers, phospho-eukaryotic initiation factor 2 subunit α, glucose-regulated protein 78, X-box binding protein 1, inositol-requiring enzyme 1, and C/EBP homologous protein and the nuclear factor-kappaB-mediated inflammation were significantly reduced in the KME group (P < .05). In contrast, the expression levels of antioxidative enzymes regulated by nuclear factor erythroid 2-related factor-2 were elevated (P < .05). The amyloid-beta expression levels of the KME group were lower than that of the control group (P < .05). Moreover, the expression levels of Bcl-2-associated X, and caspases-3 and -9 were downregulated, with a concomitant upregulation of B cell lymphoma 2 (P < .05). Accordingly, KME provide neuronal cell protection via suppressing ER stress and caspase cascade signaling.

High copper concentrations produce genotoxicity and cytotoxicity in bovine cumulus cells

The aim of this study was to investigate the cytotoxic and genotoxic effects of high copper (Cu) concentrations on bovine cumulus cells (CCs) cultured in vitro. We evaluated the effect of 0, 120, 240, and 360 μg/dL Cu added to in vitro maturation (IVM) medium on CC viability assessed by the trypan blue (TB)-fluorescein diacetate (FDA) and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays, apoptosis, and DNA damage. Differences in cell viability assessed by TB-FDA were not significant among CC treated with 0, 120, 240, and 360 μg/dL Cu. However, mitochondrial activity assessed by MTT was lower in CC cultured with 120, 240, and 360 μg/dL Cu as compared with the control (p < 0.01). Percentages of apoptotic cells were higher when CCs were treated with 120, 240, and 360 μg/dL Cu (p < 0.05) due to higher frequencies of late apoptotic cells (p < 0.05). The frequency of live cells diminished in a dose-dependent manner when Cu was added to the culture medium. Whereas genetic damage index (GDI) increased significantly in CC cultured in the presence of 240 and 360 μg/dL Cu (p ˂ 0.05), DNA damage increased at all Cu concentrations tested (p ˂ 0.05). These results indicate that Cu induces cytotoxic and genotoxic effects in bovine CC.

Copper and Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of adult neurode-generation and is characterised by progressive loss of cognitive function leading to death. The neuropathological hallmarks include extracellular amyloid plaque accumulation in affected regions of the brain, formation of intraneuronal neurofibrillary tangles, chronic neuroinflammation, oxidative stress, and abnormal biometal homeostasis. Of the latter, major changes in copper (Cu) levels and localisation have been identified in AD brain, with accumulation of Cu in amyloid deposits, together with deficiency of Cu in some brain regions. The amyloid precursor protein (APP) and the amyloid beta (Aβ) peptide both have Cu binding sites, and interaction with Cu can lead to potentially neurotoxic outcomes through generation of reactive oxygen species. In addition, AD patients have systemic changes to Cu metabolism, and altered Cu may also affect neuroinflammatory outcomes in AD. Although we still have much to learn about Cu homeostasis in AD patients and its role in disease aetiopathology, therapeutic approaches for regulating Cu levels and interactions with Cu-binding proteins in the brain are currently being developed. This review will examine how Cu is associated with pathological changes in the AD brain and how these may be targeted for therapeutic intervention.

Dietary high cholesterol and trace metals in the drinking water increase levels of ABCA1 in the rabbit hippocampus and temporal cortex

BACKGROUND

Cholesterol-fed rabbits have been documented to show increased amyloid-β (Aβ) deposits in the brain that can be exacerbated by the quality of drinking water especially if rabbits drink tap water or distilled water containing copper. One mechanism of cholesterol and Aβ clearance may be through the ATP-binding cassette transporter A1 (ABCA1).

OBJECTIVE AND METHODS

Using an ABCA1 antibody, we determined the number of ABCA1-immunopositive neurons in three areas of rabbit brain as a function of feeding 2% cholesterol and providing tap water, distilled water, or distilled water to which aluminum, copper, or zinc was added.

RESULTS

The number of neurons with ABCA1 immunoreactivity was increased significantly as a result of dietary cholesterol in the rabbit hippocampus and inferior and superior temporal cortex. The number of neurons with ABCA1 immunoreactivity was further increased in all three areas as a result of cholesterol-fed rabbits drinking tap water or distilled water with copper. Finally, cholesterol-fed rabbits that drank distilled water with aluminum also showed an increased number of ABCA1-immunopositive neurons in inferior and superior temporal cortex.

CONCLUSIONS

These data suggest that ABCA1 levels increase in parallel with previously documented increases in Aβ levels as a result of high dietary cholesterol and copper in the drinking water. Addition of aluminum to distilled water may have a similar effect in the temporal cortex. ABCA1 has been proposed as a means of clearing Aβ from the brain and manipulations that increase Aβ also result in an increase of clearance machinery.

Copper induced apoptosis in Caco-2 and Hep-G2 cells: Expression of caspases 3, 8 and 9, AIF and p53

Copper (Cu) is an essential trace metal needed to ensure cell function. However, when present at high concentrations it becomes toxic to organisms. Cell death, induced by toxic levels of copper, was previously observed in in vitro studies. However, there is no consensus about the cell death pathway induced by Cu and it is still not known whether this occurs as a result of the direct action of the metal or by indirect effects. In the present work, we intend to identify the influence of different Cu concentrations in the induction of apoptosis and to explore the potential signaling pathways, using two different in vitro cell culture models (Caco-2 and Hep-G2). Cells were exposed, during 6, 12, 24 and 48h, to Cu concentrations corresponding to IC50 and 1/8 of IC50, according to the viability assays. Then, considering the different apoptosis pathways, the expression of caspases 3, 8 and 9, apoptosis inducing factor (AIF) and p53 genes was analyzed by quantitative real time PCR. The results suggested that different Cu concentrations could trigger different apoptotic pathways, at different times of exposure. In both cell lines, apoptosis seems to be initiated by caspase independent pathway and intrinsic pathway, followed by extrinsic pathway. In conclusion, this study demonstrates that Cu induces the activation of apoptosis through caspase dependent and independent pathways, also suggesting that apoptosis activation mechanism is dependent on the concentration, time of exposure to Cu and cell type.

Regional Distribution of Copper, Zinc and Iron in Brain of Wistar Rat Model for Non-Wilsonian Brain Copper Toxicosis

In previous studies, we have reported first in vivo evidence of copper deposition in the choroid plexus, cognitive impairments, astrocytes swelling (Alzheimer type II cells) and astrogliosis (increase in number of astrocytes), and degenerated neurons coupled with significant increase in the hippocampus copper and zinc content in copper-intoxicated Wistar rats. Nonetheless, hippocampus iron levels were not affected by chronic copper-intoxication. Notwithstanding information on distribution of copper, zinc and iron status in different regions of brain due to chronic copper exposure remains fragmentary. In continuation with our previous study, the aim of this study was to investigate the effects of intraperitoneally injected copper lactate (0.15 mg Cu/100 g body weight) daily for 90 days on copper, zinc and iron levels in different regions of the brain using atomic absorption spectrophotometry. Copper-intoxicated group showed significantly increased cortex, cerebellum and striatum copper content (76, 46.8 and 80.7 % increase, respectively) compared to control group. However, non-significant changes were observed for the zinc and iron content in cortex, cerebellum and striatum due to chronic copper exposure. In conclusion, the current study demonstrates that chronic copper toxicity causes differential copper buildup in cortex, cerebellum and striatum region of central nervous system of male Wistar rats; signifying the critical requirement to discretely evaluate the effect of copper neurotoxicity in different brain regions, and ensuing neuropathological and cognitive dysfunctions.

Effects of Copper and/or Cholesterol Overload on Mitochondrial Function in a Rat Model of Incipient Neurodegeneration

Copper (Cu) and cholesterol (Cho) are both associated with neurodegenerative illnesses in humans and animals models. We studied the effect in Wistar rats of oral supplementation with trace amounts of Cu (3 ppm) and/or Cho (2%) in drinking water for 2 months. Increased amounts of nonceruloplasmin-bound Cu were observed in plasma and brain hippocampus together with a higher concentration of ceruloplasmin in plasma, cortex, and hippocampus. Cu, Cho, and the combined treatment Cu + Cho were able to induce a higher Cho/phospholipid ratio in mitochondrial membranes with a simultaneous decrease in glutathione content. The concentration of cardiolipin decreased and that of peroxidation products, conjugated dienes and lipoperoxides, increased. Treatments including Cho produced rigidization in both the outer and inner mitochondrial membranes with a simultaneous increase in permeability. No significant increase in Cyt C leakage to the cytosol was observed except in the case of cortex from rats treated with Cu and Cho nor were there any significant changes in caspase-3 activity and the Bax/Bcl2 ratio. However, the A β (1-42)/(1-40) ratio was higher in cortex and hippocampus. These findings suggest an incipient neurodegenerative process induced by Cu or Cho that might be potentiated by the association of the two supplements.

Role of copper and cholesterol association in the neurodegenerative process

Age is one of the main factors involved in the development of neurological illnesses, in particular, Alzheimer, and it is widely held that the rapid aging of the world population is accompanied by a rise in the prevalence and incidence of Alzheimer disease. However, evidence from recent decades indicates that Cu and Cho overload are emerging causative factors in neurodegeneration, a hypothesis that has been partially investigated in experimental models. The link between these two variables and the onset of Alzheimer disease has opened up interesting new possibilities requiring more in-depth analysis. The aim of the present study was therefore to investigate the effect of the association of Cu + Cho (CuCho) as a possible synergistic factor in the development of an Alzheimer-like pathology in Wistar rats. We measured total- and nonceruloplasmin-bound Cu and Cho (free and sterified) contents in plasma and brain zones (cortex and hippocampus), markers of oxidative stress damage, inflammation, and programmed cell death (caspase-3 and calpain isoforms). The ratio beta-amyloid (1-42)/(1-40) was determined in plasma and brain as neurodegenerative biomarker. An evaluation of visuospatial memory (Barnes maze test) was also performed. The results demonstrate the establishment of a prooxidative and proinflammatory environment after CuCho treatment, hallmarked by increased TBARS, protein carbonyls, and nitrite plus nitrate levels in plasma and brain zones (cortex and hippocampus) with a consequent increase in the activity of calpains and no significant changes in caspase-3. A simultaneous increase in the plasma Aβ1-42/Aβ1-40 ratio was found. Furthermore, a slight but noticeable change in visuospatial memory was observed in rats treated with CuCho. We conclude that our model could reflect an initial stage of neurodegeneration in which Cu and Cho interact with one another to exacerbate neurological damage.

Hepatic and hippocampus iron status is not altered in response to increased serum ceruloplasmin and serum "free" copper in Wistar rat model for non-Wilsonian brain copper toxicosis

Copper and iron dyshomeostasis has been implicated directly or indirectly in the pathogenesis of neurodegenerative diseases. Previously, we have shown the first in vivo evidence of significant increase in the hippocampus copper and zinc content with spatial memory impairments, astrocytes swelling (Alzheimer type-II cells) coupled with increase in the number of astrocytes, copper deposition in the choroid plexus, and degenerated neurons in copper-intoxicated Wistar rats. In continuation with our previous study, the aim of this study was to further investigate the effects of intraperitoneally injected copper lactate (0.15 mg Cu/100 g body weight) daily for 90 days on serum "free" copper levels, iron levels in the liver, and hippocampus by atomic absorption spectrophotometry and histopathological study of the liver and brain tissues of Wistar rats using Perls' Prussian blue (PPB) stain. A massive significant increase in serum "free" copper (79.48% increase) along with strong correlation (r = 0.978) was found between serum copper and serum "free" copper in copper-intoxicated rats. No significant difference was detected in hepatic and hippocampus iron levels between control and copper-intoxicated rats. PPB stain demonstrated very few scattered grade 1 haemosiderin deposits within sinusoidal cells predominantly Kupffer cells; however, brain sections were negatively stained with PPB stain. In conclusion, the current study demonstrates that chronic copper toxicity causes increase in serum "free" copper, which may serve as predisposing factor for the development of neurodegeneration and memory deficits, and grade 1 haemosiderin deposition in Kupffer cells without altering hepatic and hippocampus iron levels in male Wistar rats.

Links between copper and cholesterol in Alzheimer's disease

Altered copper homeostasis and hypercholesterolemia have been identified independently as risk factors for Alzheimer's disease (AD). Abnormal copper and cholesterol metabolism are implicated in the genesis of amyloid plaques and neurofibrillary tangles (NFT), which are two key pathological signatures of AD. Amyloidogenic processing of a sub-population of amyloid precursor protein (APP) that produces Aβ occurs in cholesterol-rich lipid rafts in copper deficient AD brains. Co-localization of Aβ and a paradoxical high concentration of copper in lipid rafts fosters the formation of neurotoxic Aβ:copper complexes. These complexes can catalytically oxidize cholesterol to generate H₂O₂, oxysterols and other lipid peroxidation products that accumulate in brains of AD cases and transgenic mouse models. Tau, the core protein component of NFTs, is sensitive to interactions with copper and cholesterol, which trigger a cascade of hyperphosphorylation and aggregation preceding the generation of NFTs. Here we present an overview of copper and cholesterol metabolism in the brain, and how their integrated failure contributes to development of AD.

Ursolic acid improves high fat diet-induced cognitive impairments by blocking endoplasmic reticulum stress and IκB kinase β/nuclear factor-κB-mediated inflammatory pathways in mice

Evidence suggests that obesity-induced cognitive impairments are driven by in brain inflammatory responses and inflammation-mediated brain insulin resistance. Ursolic acid (UA), a triterpenoid compound, has many important biological functions, including antioxidant and anti-inflammatory activities. Here, we evaluated the effect of UA on cognitive impairment induced by a high-fat diet (HFD), and we explored the potential mechanisms mediating this effect. Results showed that UA administration significantly improved the behavioral performance of C57/BL6J mice fed a HFD in both the step-through test and the Morris water maze task. These results were associated with the inhibition of endoplasmic reticulum stress and IκB kinase β/nuclear factor-κB-mediated inflammatory signaling and the restoration of insulin signaling and phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway. UA administration also increased memory-related protein expression in the hippocampus of mice given a HFD. However, the neuroprotective effects of UA were blocked by an intracerebroventricular (i.c.v.) injection of PI-103, a specific PI3K 110α inhibitor. These results suggest that UA may be a potent candidate for the prevention and treatment of cognitive deficits caused by type 2 diabetes.

Quercetin activates AMP-activated protein kinase by reducing PP2C expression protecting old mouse brain against high cholesterol-induced neurotoxicity

It is known that a high-cholesterol diet induces oxidative stress, inflammatory response, and beta-amyloid (Abeta) accumulation in mouse brain, resulting in neurodegenerative changes. Quercetin, a naturally occurring flavonoid, has been reported to possess numerous biological activities beneficial to health. Our previous studies have demonstrated that quercetin protects mouse brain against D-galactose-induced oxidative damage. Against this background, we evaluated the effect of quercetin on high-cholesterol-induced neurotoxicity in old mice and explored its potential mechanism. Our results showed that oral administration of quercetin significantly improved the behavioural performance of high-cholesterol-fed old mice in both a step-through test and the Morris water maze task. This is at least in part caused by decreasing ROS and protein carbonyl levels and restoring Cu--Zn superoxide dismutase (Cu, Zn-SOD) activity. Furthermore, quercetin also significantly activated the AMP-activated protein kinase (AMPK) via down-regulation of protein phosphatase 2C (PP2C), which reduced the integral optical density (IOD) of activated microglia cells and CD11b expression, down-regulated iNOS and cyclooxygenase-2 (COX-2) expression, and decreased IL-1beta, IL-6, and TNF-alpha expression in the brains of high-cholesterol-fed old mice through the suppression of NF-kappaB p65 nuclear translocation. Moreover, AMPK activation significantly increased 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase and acetyl-CoA carboxylase (ACC) phosphorylation and reduced fatty acid synthase (FAS) expression in the brains of high-cholesterol-fed old mice, which reduced cholesterol levels, down-regulated cholesterol 24-hydroxylase (CYP46A1) and beta-amyloid converting enzyme 1 (BACE1) expression, decreased eukaryotic translation initiation factor 2alpha (eIF2alpha) phosphorylation, and lowered Abeta deposits. However, the neuroprotective effect of quercetin was weakened by intraperitoneal injection of compound C, an AMPK inhibitor. These results suggest that AMPK activated by quercetin may be a potential target to enhance the resistance of neurons to age-related diseases.

The efficiacy of bismuth subnitrate against genotoxicity and oxidative stress induced by aluminum sulphate

Aluminum (Al) is commonly used in industrial processes and drugs and is thought to induce erythrocytes damage via activation of oxidative stress. Recently, bismuth (Bi)-containing drugs are used in the treatment of various diseases. However, uncertain effects of Bi in blood tissue may participate in the therapeutic efficacy of Bi compounds as related to metals. Hence, this study aimed to determine the roles on human blood cells of the various concentrations of aluminum sulphate (Al2 (SO4)3) and bismuth subnitrate (BSN), separate and together. With this aim, oxidative status was assessed on erythrocytes by measuring following oxidative stress markers: reduced glutathione (GSH), superoxide dismutase (SOD), glucose-6-phosphate dehydrogenase (G-6-PDH) and catalase (CAT). Two chemicals were tested for their ability to induce cytogenetic change in human lymphocytes using assays for chromosome aberrations (CAs) and sister chromatid exchanges (SCEs). Our results showed that high dose of Al2(SO4)3 (20 µg/mL) caused oxidative stress and increased CA and SCE frequencies. Whereas, BSN doses did not change CA and SCE rates. Moreover, it led to changes of antioxidant capacity at different concentrations. After concomitant treatment with Al2(SO 4)3 and BSN, the effects of BSN doses were different on enzyme activities and decreased the genotoxic damage. However, the high dose of BSN and Al2(SO4)3 was shown to enhance the frequencies of CAs and SCEs in a synergistic manner. In conclusion, BSN could be effective in the protection against the blood toxicity of Al 2(SO4)3.

NGF-Dependent activation of TrkA pathway: A mechanism for the neuroprotective effect of troxerutin in D-galactose-treated mice

D-galactose-(D-gal)-treated mouse, with cognitive impairment, has been used for neurotoxicity investigation and anti-neurotoxicity pharmacology research. In this study, we investigated the mechanism underlying the neuroprotective effect of troxerutin. The results showed that troxerutin improved behavioral performance in D-gal-treated mice by elevating Cu, Zn-superoxide dismutases (Cu, Zn-SOD) activity and decreasing reactive oxygen species levels. Furthermore, our results showed that troxerutin significantly promoted nerve growth factor (NGF) mRNA expression which resulted in TrkA activation. On one hand, NGF/TrkA induced activation of Akt and ERK1/2, which led to neuronal survival; on the other hand, NGF/TrkA mediated CaMKII and CREB phosphorylation and increased PSD95 expression, which improved cognitive performance. However, the neuroprotective effect of troxerutin was blocked by treatment with K252a, an antagonist for TrkA. No neurotoxicity was observed in mice treated with K252a or troxerutin alone. In conclusion, administration of troxerutin to D-gal-injected mice attenuated cognitive impairment and brain oxidative stress through the activation of NGF/TrkA signaling pathway.

Metal ion physiopathology in neurodegenerative disorders

Metal dyshomeostasis in the brain (BMD) has often been proposed as a possible cause for several neurodegenerative disorders (NDs). Nevertheless, the precise nature of the biochemical mechanisms of metal involvement in NDs is still largely unknown. Mounting evidence suggests that normal aging itself is characterized by, among other features, a significant degree of metal ion dysmetabolism in the brain. This is probably the result of a progressive deterioration of the metal regulatory systems and, at least in some cases, of life-long metal exposure and brain accumulation. Although alterations of metal metabolism do occur to some extent in normal aging, they appear to be highly enhanced under various neuropathological conditions, causing increased oxidative stress and favoring abnormal metal-protein interactions. Intriguingly, despite the fact that most common NDs have a distinct etiological basis, they share striking similarities as they are all characterized by a documented brain metal impairment. This review will primarily focus on the alterations of metal homeostasis that are observed in normal aging and in Alzheimer's disease. We also present a brief survey on BMD in other NDs (Amyotrophic Lateral Sclerosis, Parkinson's, and Prion Protein disease) in order to highlight what represents the most reliable evidence supporting a crucial involvement of metals in neurodegeneration. The opportunities for metal-targeted pharmacological strategies in the major NDs are briefly outlined as well.

Purple sweet potato color alleviates D-galactose-induced brain aging in old mice by promoting survival of neurons via PI3K pathway and inhibiting cytochrome C-mediated apoptosis

Purple sweet potato color (PSPC), a class of naturally occurring anthocyanins, protects brain function against oxidative stress induced by D-galactose (D-gal) (Sigma-Aldrich, St. Louis, MO, USA). Our data showed that PSPC enhanced open-field activity, decreased step-through latency, and improved spatial learning and memory ability in D-gal-treated old mice by decreasing advanced glycation end-products' (AGEs) formation and the AGE receptor (RAGE) expression, and by elevating Cu,Zn-superoxide dismutase (Cu,Zn-SOD) (Sigma-Aldrich) and catalase (CAT) expression and activity. Cleavage of caspase-3 and increased terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick-end-labeling (TUNEL)-positive cells in D-gal-treated old mice were inhibited by PSPC, which might be attributed to its antioxidant property. PSPC also suppressed the activation of c-Jun NH(2)-terminal kinase (JNK) and the release of cytochrome c from mitochondria that counteracted the onset of neuronal apoptosis in D-gal-treated old mice. Furthermore, it was demonstrated that phosphoinositide 3-kinase (PI3K) activation was required for PSPC to promote the neuronal survival accompanied with phosphorylation and activation of Akt and p44/42 mitogen-activated protein kinase (MAPK) by using PI3K inhibitor LY294002 (Cell Signaling Technology, Inc., Beverly, MA, USA), implicating a neuronal survival mechanism. The present results suggest that neuronal survival promoted by PSPC may be a potentially effective method to enhance resistance of neurons to age-related disease.

Trace amounts of copper exacerbate beta amyloid-induced neurotoxicity in the cholesterol-fed mice through TNF-mediated inflammatory pathway

Evidence has been gathered to suggest that trace amounts of copper induce neurotoxicity by interaction with elevated cholesterol in diet. Step-through task and Morris water maze task were used to evaluate cognitive function in the animals. Although a 16-week copper treatment alone in mice showed no significant change in learning and memory performances, cholesterol treatment significantly induced learning and memory impairments, which could be exacerbated by the co-treatment with copper. Immunohistochemical studies revealed that trace amounts of copper further stimulated the amyloid precursor protein (APP) upregulation and contributed to amyloid beta-peptide (Abeta) deposition in the brain of cholesterol-fed mice. Western blot analysis showed that copper also increased the protein expression levels of tumor necrosis factor-alpha (TNF-alpha) and the degradation of IkappaB proteins in the brain of cholesterol-fed mice. Furthermore, increased production of high inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) expressions were detected in the hippocampus and cerebral cortex of copper and cholesterol co-treated mice by immunohistochemical analysis. These findings suggest that trace amounts of copper could induce APP upregulation, activate inflammatory pathway and exacerbate neurotoxicity in cholesterol-fed mice.

Chronic copper exposure exacerbates both amyloid and tau pathology and selectively dysregulates cdk5 in a mouse model of AD

Excess copper exposure is thought to be linked to the development of Alzheimer's disease (AD) neuropathology. However, the mechanism by which copper affects the CNS remains unclear. To investigate the effect of chronic copper exposure on both beta-amyloid and tau pathologies, we treated young triple transgenic (3xTg-AD) mice with 250 ppm copper-containing water for a period of 3 or 9 months. Copper exposure resulted in altered amyloid precursor protein processing; increased accumulation of the amyloid precursor protein and its proteolytic product, C99 fragment, along with increased generation of amyloid-beta peptides and oligomers. These changes were found to be mediated via up-regulation of BACE1 as significant increases in BACE1 levels and deposits were detected around plaques in mice following copper exposure. Furthermore, tau pathology within hippocampal neurons was exacerbated in copper-exposed 3xTg-AD group. Increased tau phosphorylation was closely correlated with aberrant cdk5/p25 activation, suggesting a role for this kinase in the development of copper-induced tau pathology. Taken together, our data suggest that chronic copper exposure accelerates not only amyloid pathology but also tau pathology in a mouse model of AD.

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

Amyloid beta peptide (Abeta), generated by proteolytic cleavage of the amyloid precursor protein (APP), play a pivotal role in the pathogenesis of Alzheimer's disease (AD). The key step in the generation of Abeta is cleavage of APP by beta-site APP-cleaving enzyme 1 (BACE1). There is increasing evidence supporting an interaction between APP, Abeta and metal ions. Both APP and Abeta affect ion homeostasis. Conversely, metal ions may interact with several AD-associated pathways involved in neurofibrillary tangle formation, secretase cleavage of APP, proteolytic degradation of Abeta and the generation of reactive oxygen species. However, the underlying mechanisms remain elusive. Here we first reported the differential effects of AD-related metal ions at subtoxic concentrations on the transcription levels of APP and BACE1 in PC12 cells. Copper (Cu(2+), 50-100 microM) and manganese (Mn(2+), 50-100 microM) potently increased the expression of both APP and BACE1 in a time- and concentration-dependent pattern, while zinc (Zn(2+)), iron (Fe(2+)) and aluminum (Al(3+)) did not. To uncover the mechanism(s) of the increasing expression by these ions, we observed the effects of several antioxidants and some specific inhibitors on the up-expression of APP and BACE1 by metal ions. Curcumin almost completely blocked the effects of these irons, while minocycline and sodium ferulate slightly suppressed the increased BACE1 mRNA level. Signaling pathway specific inhibitors PD98059, SB203580 and CEP11004 modestly blocked the up-transcription of APP induced by copper. These results suggest that these irons cause differential effects on the expression of APP and BACE1 in PC12 cells, and curcumin can significantly reverse their effects.