Apurinic/apyrimidinic endonuclease 1 is a key modulator of aluminum-induced neuroinflammation

Benefits of rutin on mitochondrial function and inflammation in an aluminum-induced neurotoxicity rat model: Potential interest for the prevention of neurodegeneration

Rutin, a phenolic compound, exhibits a diverse range of biological properties, including antioxidant, anti-inflammatory, and antimicrobial effects. In this study, we aimed to investigate the potential of rutin, a naturally occurring plant bioactive molecule, to mitigate the neurotoxic effects induced by aluminum chloride (AlCl3). Over a period of 6 weeks, rats were intraperitoneally injected with AlCl3 at a weekly dose of 60 mg/kg, while rutin treatment was administered orally via gavage at a daily dose of 30 mg/kg. AlCl3 exposure resulted in a significant increase lipid peroxidation (LPO) by 316.24%, nitrate levels by 504.14%, and tumor necrosis factor-alpha (TNF-α) levels by 93.82% in brain mitochondria. Additionally, AlCl3 exposure led to a reduction in glutathione levels and the activity of antioxidant enzymes, including superoxide dismutase (SOD) by 19.74%, glutathione peroxidase (GPx) by 44.76%, and catalase by 50.50%. There was also a significant decline in the activity of mitochondrial complex enzymes. In contrast, rutin treatment significantly enhanced the activity of antioxidant enzymes while concurrently reducing lipid peroxidation levels in rats. Specifically, rutin administration exerted a modulatory effect on the inflammatory response triggered by aluminum exposure, effectively suppressing the excessive production of nitrate and TNF-α. These findings highlight the potential of rutin as an effective therapeutic strategy in mitigating and combating neuro-inflammation and oxidative stress associated with aluminum-induced toxicity, thereby effectively restoring mitochondrial function.

Neurotherapeutic effects of quercetin-loaded nanoparticles and Biochanin-A extracted from Trifolium alexandrinum on PI3K/Akt/GSK-3β signaling in the cerebral cortex of male diabetic rats

Diabetes mellitus (DM) is a severe metabolic disease that can have significant consequences for cognitive health. Bioflavonoids such as Trifolium alexandrinum (TA), quercetin (Q), and Biochanin-A (BCA) are known to exert a wide range of pharmacological functions including antihyperglycemic activity. This study aimed to investigate the neurotherapeutic effects of quercetin-loaded nanoparticles (Q-LNP) and BCA extracted from TA against diabetes-induced cerebral cortical damage through modulation of PI3K/Akt/GSK-3β and AMPK signaling pathways. Adult male Wistar albino rats (N = 25) were randomly assigned to one of five groups: control, diabetics fed a high-fat diet (HFD) for 2 weeks and intraperitoneally (i.p.) injected with STZ (40 mg/kg), and diabetics treated with Q-LNP (50 mg/kg BW/day), BCA (10 mg/kg BW/day), or TA extract (200 mg/kg BW/day). Treatments were applied by oral gavage once daily for 35 days. Diabetic rats treated with Q-LNP, BCA, and TA extract showed improvement in cognitive performance, cortical oxidative metabolism, antioxidant parameters, and levels of glucose, insulin, triglyceride, and total cholesterol. In addition, these treatments improved neurochemical levels, including acetylcholine, dopamine, and serotonin levels as well acetylcholinesterase and monoamine oxidase activities. Furthermore, these treatments lowered proinflammatory cytokine production for TNF-α and NF-κB; downregulated the levels of IL-1β, iNOS, APP, and PPAR-γ; and attenuated the expressions of PSEN2, BACE, IR, PI3K, FOXO 1, AKT, AMPK, GSK-3β, and GFAP. The histopathological examinations of the cerebral cortical tissues confirmed the biochemical results. Overall, the present findings suggest the potential therapeutic effects of TA bioflavonoids in modulating diabetes-induced cerebral cortical damage.

Inflammation in Metal-Induced Neurological Disorders and Neurodegenerative Diseases

Essential metals play critical roles in maintaining human health as they participate in various physiological activities. Nonetheless, both excessive accumulation and deficiency of these metals may result in neurotoxicity secondary to neuroinflammation and the activation of microglia and astrocytes. Activation of these cells can promote the release of pro-inflammatory cytokines. It is well known that neuroinflammation plays a critical role in metal-induced neurotoxicity as well as the development of neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Initially seen as a defense mechanism, persistent inflammatory responses are now considered harmful. Astrocytes and microglia are key regulators of neuroinflammation in the central nervous system, and their excessive activation may induce sustained neuroinflammation. Therefore, in this review, we aim to emphasize the important role and molecular mechanisms underlying metal-induced neurotoxicity. Our objective is to raise the awareness on metal-induced neuroinflammation in neurological disorders. However, it is not only just neuroinflammation that different metals could induce; they can also cause harm to the nervous system through oxidative stress, apoptosis, and autophagy, to name a few. The primary pathophysiological mechanism by which these metals induce neurological disorders remains to be determined. In addition, given the various pathways through which individuals are exposed to metals, it is necessary to also consider the effects of co-exposure to multiple metals on neurological disorders.

The bioaccessibility of adsorped heavy metals on biofilm-coated microplastics and their implication for the progression of neurodegenerative diseases

Microplastic (MP) tiny fragments (< 5 mm) of conventional and specialized industrial polymers are persistent and ubiquitous in both aquatic and terrestrial ecosystem. Breathing, ingestion, consumption of food stuffs, potable water, and skin are possible routes of MP exposure that pose potential human health risk. Various microorganisms including bacteria, cyanobacteria, and microalgae rapidly colonized on MP surfaces which initiate biofilm formation. It gradually changed the MP surface chemistry and polymer properties that attract environmental metals. Physicochemical and environmental parameters like polymer type, dissolved organic matter (DOM), pH, salinity, ion concentrations, and microbial community compositions regulate metal adsorption on MP biofilm surface. A set of highly conserved proteins tightly regulates metal uptake, subcellular distribution, storage, and transport to maintain cellular homeostasis. Exposure of metal-MP biofilm can disrupt that cellular homeostasis to induce toxicities. Imbalances in metal concentrations therefore led to neuronal network dysfunction, ROS, mitochondrial damage in diseases like Alzheimer's disease (AD), Parkinson's disease (PD), and Prion disorder. This review focuses on the biofilm development on MP surfaces, factors controlling the growth of MP biofilm which triggered metal accumulation to induce neurotoxicological consequences in human body and stategies to reestablish the homeostasis. Thus, the present study gives a new approach on the health risks of heavy metals associated with MP biofilm in which biofilms trigger metal accumulation and MPs serve as a vector for those accumulated metals causing metal dysbiosis in human body.

Effect of silymarin on the relative gene expressions of some inflammatory cytokines in the liver of CCl4-intoxicated male rats

The intensive exposure of the liver cells to any type of noxae, such as viruses, drugs, alcohols, and xenobiotics could induce hepatic inflammation through the upregulation of gene expression of several fibrotic and inflammatory mediators. So, our study assessed the role of silymarin on the inflammatory response induced by carbon tetrachloride (CCl4) as an example of xenobiotics on liver tissues in male rats. Forty-eight Wister male rats (weight: 130 ± 10) were housed for 14 days and then divided randomly into six groups: control, SLY: rats received only silymarin orally for 12 weeks (daily), CO: rats were injected with corn oil for 8 weeks (3 times weekly), CCl4: rats were injected with CCl4 solubilized in corn oil for 8 weeks (day by day), Treated: rats received silymarin for 4 weeks after CCl4 injection, Protected: rats received silymarin for 4 weeks before and 8 weeks during CCl4 injection. When the treatment period for the rats was over, they underwent scarification after anesthesia. Then, the sera were extracted from the collected blood for the determination of irisin levels, liver functions, and lipid profiles. Liver tissues were separated for the histopathological examinations, the determination of oxidative stress (OS) parameters content, and the relative gene expression of inflammatory cytokines; nuclear factor kappa (NF)-κB, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, cyclooxygenase (COX)-2, and transforming growth factor beta (TGF-β). The findings showed that silymarin reduced liver inflammation by overcoming the OS process and inflammatory cytokines production which was stimulated by CCl4. These results were confirmed by histopathology of liver tissues.

Targeting Neuroinflammation with Abscisic Acid Reduces Pain Sensitivity in Females and Hyperactivity in Males of an ADHD Mice Model

Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopmental syndrome characterized by dopaminergic dysfunction. In this study, we aimed to demonstrate that there is a link between dopaminergic deficit and neuroinflammation that underlies ADHD symptoms. We used a validated ADHD mice model involving perinatal 6-OHDA lesions. The animals received abscisic acid (ABA), an anti-inflammatory phytohormone, at a concentration of 20 mg/L (drinking water) for one month. We tested a battery of behavior tests, learning and memory, anxiety, social interactions, and pain thresholds in female and male mice (control and lesioned, with or without ABA treatment). Postmortem, we analyzed microglia morphology and Ape1 expression in specific brain areas related to the descending pain inhibitory pathway. In females, the dopaminergic deficit increased pain sensitivity but not hyperactivity. In contrast, males displayed hyperactivity but showed no increased pain sensitivity. In females, pain sensitivity was associated with inflammatory microglia and lower Ape1 levels in the anterior cingulate cortex (ACC) and posterior insula cortex (IC). In addition, ABA treatment alleviated pain sensitivity concomitant with reduced inflammation and normalized APE1. In males, ABA reduced hyperactivity but had no significant effect on inflammation in these areas. This is the first study proving a sex-dependent association between dopamine dysfunction and inflammation in specific brain areas, hence leading to different behavioral outcomes in a mouse model of ADHD. These findings provide new clues for potential treatments for ADHD.

Garden Cress (Lepidium sativum) Seeds Ameliorated Aluminum-Induced Alzheimer Disease in Rats Through Antioxidant, Anti-Inflammatory, and Antiapoptotic Effects

Background

Bioaccumulation of aluminum in the brain is associated with adverse neuroinflammatory and neurodegenerative changes, such as those seen in Alzheimer's disease (AD).

Objective

This study aimed to assess the impact of the administration of Lepidium sativum (LS) extract on behavioral, biochemical, and cerebral histopathological changes in rats with AlCl₃-induced AD and explore the mechanism behind this effect.

Materials and Methods

This study was conducted on 40 male albino rats divided into four groups (n=10): LS (control, 20 mg/kg body weight for 8 weeks), AD (AlCl_3, 10 mg/kg body weight), and an LS-treated AD group. Behavioral assessment included radial armed maze and active avoidance training tests. Proinflammatory cytokines, oxidant/antioxidant markers, Aβ, AchE, tau protein, TGFβ₁, homocysteine, folic acid, and vitamin B₁₂ were biochemically assessed in the serum. The cerebral cortex was histopathologically examined.

Results

AlCl₃ administration significantly impaired rats' memory, indicating AD-like behavioral changes, significantly increased (P<0.001) oxidative stress markers, enhanced proinflammatory cytokines, and significantly increased AChE (P<0.001) adding to cytotoxic effects and neuronal loss in the cerebral cortex. LS administration significantly improved the antioxidant parameters, reduced proinflammatory cytokines, and alleviated AD-associated histopathological changes.

Conclusion

LS ameliorated AlCl₃-induced changes through its antioxidant, anti-inflammatory, and antiapoptotic effects, suggesting that it has a neuroprotective effect.

Assessment of the neuroprotective potential of d-cycloserine and l-serine in aluminum chloride-induced experimental models of Alzheimer’s disease: In vivo and in vitro studies

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by the accumulation of amyloid-β (Aβ) plaques and neurofibrillary tangles in the brain accompanied by synaptic dysfunction and neurodegeneration. No effective treatment has been found to slow the progression of the disease. Therapeutic studies using experimental animal models have therefore become very important. Therefore, this study aimed to investigate the possible neuroprotective effect of D-cycloserine and L-serine against aluminum chloride (AlCl₃)-induced AD in rats. Administration of AlCl₃ for 28 days caused oxidative stress and neurodegeneration compared to the control group. In addition, we found that aluminum decreases α-secretase activity while increasing β-secretase and γ-secretase activities by molecular genetic analysis. D-cycloserine and L-serine application resulted in an improvement in neurodegeneration and oxidative damage caused by aluminum toxicity. It is believed that the results of this study will contribute to the synthesis of new compounds with improved potential against AlCl₃-induced neurodegeneration, cognitive impairment, and drug development research.

Phosphodiesterase (PDE) III inhibitor, Cilostazol, improved memory impairment in aluminum chloride-treated rats: modulation of cAMP/CREB pathway

The most prevalent type of dementia is Alzheimer's disease (AD), which is currently incurable. Existing treatments for Alzheimer's disease, such as acetylcholinesterase inhibitors, are only effective for symptom relief. Disease-modifying medications for Alzheimer's disease are desperately required, given the enormous burdens that the disease places on individuals and communities. Phosphodiesterase (PDE) inhibitors are gaining a lot of attention in the research community because of their potential in treating age-related cognitive decline. Cilostazol is a selective PDE III inhibitor used as antiplatelet agent through cAMP response element-binding (CREB) protein phosphorylation pathway (cAMP/CREB). The neuroprotective effect of cilostazol in AD-like cognitive decline in rats was investigated in this study. After 2 months of intraperitoneal administration of 10 mg/kg aluminum chloride, Morris water maze and Y-maze (behavioral tests) were performed. After that, histological and biochemical examinations of the hippocampal region were carried out. Aluminum chloride-treated rats showed histological, biochemical, and behavioral changes similar to Alzheimer's disease. Cilostazol improved rats' behavioral and histological conditions, raised neprilysin level while reduced levels of amyloid-beta protein and phosphorylated tau protein. It also decreased the hippocampal levels of tumor necrosis factor-alpha, nuclear factor-kappa B, FAS ligand, acetylcholinesterase content, and malondialdehyde. These outcomes demonstrate the protective activity of cilostazol versus aluminum-induced memory impairment.

Resveratrol alleviates aluminum-induced intestinal barrier dysfunction in mice

BACKGROUND

Aluminum is mainly exposed to the general population through food and water, and is absorbed into the systemic circulation through intestine, which in turn damages the intestinal barrier.

METHODS

The mice model of subchronic exposure to aluminum chloride (AlCl₃ ) was established via oral. Tail suspension test was used to detect depressive behavior. H&E staining was performed to assess pathological intestinal injury. Intestinal permeability was estimated by exogenous Evans blue content. The level of inflammatory cytokines and tight junction protein were assessed via ELISA and western blotting. Simultaneously, resveratrol (Rsv, an agonist of Sirt1) was evaluated the protective role against intestinal barrier injuries caused by aluminum exposure.

RESULTS

Our results showed that AlCl₃ induced depressive-like behavior, intestinal pathological damage and intestinal barrier permeability, resulting in intestinal barrier dysfunction. Besides, aluminum induced the expression of inflammatory cytokines, which further triggered IRF8-MMP9-mediated downregulation of tight junction proteins including CLD1, OCLD and ZO-1. After Rsv treatment, SIRT1 expression was increased, depressive symptom was improved, pathological injury was reduced, inflammatory reaction was alleviated, and intestinal barrier function restored.

CONCLUSION

Our findings revealed that aluminum exposure induced intestinal barrier dysfunction by IRF8-MMP9 signaling pathway. Rsv alleviated these injuries via activating SIRT1.

APE1/Ref-1 Role in Inflammation and Immune Response

Apurinic/apyrimidinic endonuclease 1/redox effector factor 1 (APE1/Ref-1) is a multifunctional enzyme that is essential for maintaining cellular homeostasis. APE1 is the major apurinic/apyrimidinic endonuclease in the base excision repair pathway and acts as a redox-dependent regulator of several transcription factors, including NF-κB, AP-1, HIF-1α, and STAT3. These functions render APE1 vital to regulating cell signaling, senescence, and inflammatory pathways. In addition to regulating cytokine and chemokine expression through activation of redox sensitive transcription factors, APE1 participates in other critical processes in the immune response, including production of reactive oxygen species and class switch recombination. Furthermore, through participation in active chromatin demethylation, the repair function of APE1 also regulates transcription of some genes, including cytokines such as TNFα. The multiple functions of APE1 make it an essential regulator of the pathogenesis of several diseases, including cancer and neurological disorders. Therefore, APE1 inhibitors have therapeutic potential. APE1 is highly expressed in the central nervous system (CNS) and participates in tissue homeostasis, and its roles in neurodegenerative and neuroinflammatory diseases have been elucidated. This review discusses known roles of APE1 in innate and adaptive immunity, especially in the CNS, recent evidence of a role in the extracellular environment, and the therapeutic potential of APE1 inhibitors in infectious/immune diseases.

Chitosan and solid lipid nanoparticles enhance the efficiency of alpha-lipoic acid against experimental neurotoxicity

Alpha-lipoic acid (α-LA) is characterized by its unpleasant odor, poor bioavailability and stability. Nanotechnology was applied to overcome this limitation. So we aimed in this study to formulate α-LA in two different forms of chitosan nanoparticles (CsNPs) and solid lipid nanoparticles (SLNPs) and characterize them in terms of physical properties and biological activities against aluminum chloride (AlCl₃)-induced neurotoxicity in rats. The vivo study was processed on 50 rats divided into 5 groups as follow: control, neurotoxic, treated α-LA, treated α-lipoic acid-loaded chitosan nanoparticles (α-LA-CsNPs) and treated α-lipoic acid-loaded solid lipid nanoparticles (α-LA-SLNPs) groups. The result was depicted by transmission electron microscopy (TEM) revealed that α-LA-SLNPs had a regular spherical shape while α-LA-CsNPs showed an irregular spherical form. Dynamic light scattering (DLS) analysis showed that the average particle size for α-LA-SLNPs was about 71 nm and for α-LA-CsNPs was about 126 nm. After the experimental period, we observed that AlCl₃ administration significantly increased oxidative stress, neuroinflammation and apoptosis and decreased brain fatty acid contentsand brain-derived neurotrophic factor,while α-LA, α-LA-CsNPs and α-LA-SLNPs were able to ameliorate these negative changes in the neurotoxic rats. However, the effect of the α-LA-loaded NPs was more prominent than that of pristine α-LA but the α-LA-SLNPs group was almost close to the control group. Conclusion: α-LA can attenuate neurotoxicity induced by AlCl3, attributed to its anti-inflammatory, antioxidant and anti-apoptotic activities in addition to the effectiveness of the encapsulation technique that can increase the efficiency and stability of α-LA. Moreover, α-LA-SLNPs are more efficient than α-LA-CsNPs.

Aluminum impairs cognitive function by activating DDX3X-NLRP3-mediated pyroptosis signaling pathway

INTRODUCTION

Aluminum is a kind of chemical contaminants in food which can induce neurotoxicity. Aluminum exposure is closely related to neurodegenerative diseases (ND), in which neuroinflammation might involve. However, the molecular mechanism of aluminum-induced neuroinflammation through pyroptosis is not fully clarified yet.

MATERIAL AND METHODS

The mice model of subacute exposure to aluminum chloride (AlCl₃) was established. BV2 microglia cells was treated with AlCl₃ in vitro. Resveratrol (Rsv) was adopted as intervention agent.

RESULTS

Our results showed that aluminum induced cognitive impairment, destroying blood brain barrier (BBB), and causing nerve injury in mice. Meanwhile, aluminum could stimulate nucleotide oligomerization domain-like receptor family pyrin domain containing protein 3 (NLRP3) inflammasome assembly and activate caspase-1 (CASP1), inducing gasdermin D (GSDMD)-mediated pyroptosis signaling, releasing cytokines IL-1β and IL-18, further promoting the activation of glial cells to magnify neuroinflammatory response. Moreover, DEAD-box helicase 3 X-linked (DDX3X) and stress granule RasGAP SH3-domain-binding protein 1 (G3BP1) both participated in neuroinflammation induced by aluminum. When co-treated with Rsv, these injuries were alleviated to some extent.

CONCLUSION

Aluminum exposure could induce nerve cell pyroptosis and neuroinflammation by DDX3X-NLRP3 inflammasome signaling pathway, which could be rescued via Rsv activating sirtuin 1 (SIRT1).

Therapeutic Applications of Resveratrol in Hepatic Encephalopathy through Its Regulation of the Microbiota, Brain Edema, and Inflammation

Hepatic encephalopathy is a common complication in patients with liver cirrhosis and portosystemic shunting. Patients with hepatic encephalopathy present a variety of clinical features, including neuropsychiatric manifestations, cognitive dysfunction, impaired gut barrier function, hyperammonemia, and chronic neuroinflammation. These pathogeneses have been linked to various factors, including ammonia-induced oxidative stress, neuronal cell death, alterations in the gut microbiome, astrocyte swelling, and blood-brain barrier disruptions. Many researchers have focused on identifying novel therapeutics and prebiotics in the hope of improving the treatment of these conditions. Resveratrol is a natural polyphenic compound and is known to exert several pharmacological effects, including antioxidant, anti-inflammatory, and neuroprotective activities. Recent studies suggest that resveratrol contributes to improving the neuropathogenic effects of liver failure. Here, we review the current evidence describing resveratrol's effects in neuropathogenesis and its impact on the gut-liver axis relating to hepatic encephalopathy. We highlight the hypothesis that resveratrol exerts diverse effects in hepatic encephalopathy and suggest that these effects are likely mediated by changes to the gut microbiota, brain edema, and neuroinflammation.

Alendronate reduces the cognitive and neurological disturbances induced by combined doses of d-galactose and aluminum chloride in mice

Neurological disturbances including cholinergic dysfunction, oxidative stress, neuroinflammation, and cognitive impairments are the well-reported consequences of old age-related disorders like Alzheimer's disease (AD) or dementia. Bisphosphonates were shown to ameliorate dementia in osteoporotic patients, neuroinflammation, and cholinesterase activity in rodents. Thus, the present study has been designed to examine the role of alendronate against cognitive and neurological disturbances in mice induced by a combined oral dose of d-galactose and aluminum chloride (AlCl₃ ) for 6 weeks. d-galactose acts as a senescence agent, whereas AlCl₃ is a neurotoxin and in combination generates neuropathologies and cognitive depletion resembling aging and AD. It was found that memory was markedly impaired in d-galactose + AlCl₃ -treated mice as assessed in different behavioral paradigms. Additionally, d-galactose + AlCl₃ led to neurotoxicity assessed on the basis of neuroinflammation, oxidative stress, glial cell activation, neuronal damage, and augmented GSK-3β level in mice hippocampus. Consequently, alendronate administration orally for 15 days in d-galactose + AlCl₃ -exposed mice prominently reversed all these behavioral and neuropathological changes. These findings show that alendronate can be a potential therapeutic molecule with multiple targets for the management of age-related neurological disorders such as AD.

Metal Imbalance in Neurodegenerative Diseases with a Specific Concern to the Brain of Multiple Sclerosis Patients

There is increasing evidence that deregulation of metals contributes to a vast range of neurodegenerative diseases including multiple sclerosis (MS). MS is a chronic inflammatory disease of the central nervous system (CNS) manifesting disability and neurological symptoms. The precise origin of MS is unknown, but the disease is characterized by focal inflammatory lesions in the CNS associated with an autoimmune reaction against myelin. The treatment of this disease has mainly been based on the prescription of immunosuppressive and immune-modulating agents. However, the rate of progressive disability and early mortality is still worrisome. Metals may represent new diagnostic and predictive markers of severity and disability as well as innovative candidate drug targets for future therapies. In this review, we describe the recent advances in our understanding on the role of metals in brain disorders of neurodegenerative diseases and MS patients.

AlCl3 exposure regulates neuronal development by modulating DNA modification

BACKGROUND

As the third most abundant element, aluminum is widespread in the environment. Previous studies have shown that aluminum has a neurotoxic effect and its exposure can impair neuronal development and cognitive function.

AIM

To study the effects of aluminum on epigenetic modification in neural stem cells and neurons.

METHODS

Neural stem cells were isolated from the forebrain of adult mice. Neurons were isolated from the hippocampi tissues of embryonic day 16-18 mice. AlCl₃ at 100 and 200 μmol/L was applied to stem cells and neurons.

RESULTS

Aluminum altered the differentiation of adult neural stem cells and caused apoptosis of newborn neurons while having no significant effects on the proliferation of neural stem cells. Aluminum application also significantly inhibited the dendritic development of hippocampal neurons. Mechanistically, aluminum exposure significantly affected the levels of DNA 5-hydroxy-methylcytosine, 5-methylcytosine, and N⁶-methyladenine in stem cells and neurons.

CONCLUSION

Our findings indicate that aluminum may regulate neuronal development by modulating DNA modifications.

APE1 inhibits foam cell formation from macrophages via LOX1 suppression

BACKGROUND

Macrophage activation and massive foam cell formation are key events in the development of Atherosclerosis (AS). Apurinic apyrimidinic endonuclease 1/Redox factor-1 (APE1) is an enzyme responsible for DNA repair and redox regulation. Recent studies indicate that APE1 is also involved in inflammatory response. We sought to explore its effect on oxidized low-density lipoprotein (oxLDL) induced macrophage activation and foam cell formation.

METHODS

Human macrophage cell line THP-1 cells were cultured and treated with oxLDL. The mRNA and protein levels of inflammatory markers for macrophage activation were measured. Foam cell formation was detected by Oil red O staining. Meanwhile the major cellular receptors responsible for oxLDL uptake and efflux were detected. Chromatin immunoprecipitation-quantitative real time PCR (ChIP-qPCR) and dual luciferase reporter assays were performed to identify the molecular mechanisms through which APE1 affects macrophage activation and foam cell formation.

RESULTS

Aberrant APE1 expression dramatically decreases the mRNA and protein of oxLDL-induced inflammatory molecules in THP-1 cells, accompanied by significantly inhibited foam cell formation. Western blot assay showed that down-regulation of LOX1, a receptor of oxLDL, is responsible for the inhibitory effect of APE1 on oxLDL induced macrophage inflammation. ChIP-qPCR assay showed that APE1 inhibits binding of the LOX1 promoter to its transcription factor Oct1, leading to suppression of LOX1.

CONCLUSION

Our data confirm the anti-inflammatory properties of APE1 and for the first-time report that APE1 suppresses foam cell formation from macrophages via the oxLDL receptor LOX1. This finding indicates that APE1 can be a therapeutic target for AS prevention.

Sildenafil ameliorates Alzheimer disease via the modulation of vascular endothelial growth factor and vascular cell adhesion molecule-1 in rats

Alzheimer disease (AD) is a chronic neurodegenerative disease with multi-pathways pathogenesis. Sildenafil is a selective phosphodiesterase-5 inhibitor with a potential benefit in the treatment of AD. This study investigated the possible mechanisms underlying the effect of sildenafil in AD with emphasis on vascular endothelial growth factor (VEGF), and vascular cell adhesion molecule-1 (VCAM-1). Twenty-four adult male rats were classified into four groups; control group: received vehicles, sildenafil-control: received sildenafil (15 mg/kg/day, p.o.), AD group received Aluminum (25 mg/kg/day, p.o.), AD-treated group: received sildenafil (15 mg/kg/day, p.o.) for 6 weeks. AD was assessed by memory performance test and confirmed by histopathological examination and immunostaining of, neurogenesis marker nestin and α-synuclein. The levels of VEGF-A, VCAM-1, oxidative stress markers and TNF-α in brain tissue were evaluated. AD rats showed histopathological evidences of AD; along with increased latency time in the memory test. There was a decrease in VEGF-A, and an increase in VCAM-1, TNF-α, and oxidative stress markers. Immunohistochemical study showed a significant increase in α-synuclein and a significant decrease in nestin expressions in brain tissues. Sildenafil administration ameliorated the histopathological changes and decreased latency time. Such effect was associated with a decrease in VCAM-1, TNF-α and oxidative stress as well as an increase in VEGF-A. Sildenafil caused a significant increase in nestin and a decrease in α-synuclein immunostaining. These findings suggested a protective effect of sildenafil via modulation of VEGF-A, and VCAM-1.

Resveratrol in Alzheimer's disease: a review of pathophysiology and therapeutic potential

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive and irreversible loss of cognitive function. The presence of senile plaques is one of the pathological markers of the disease and is associated with the onset of neuroinflammatory mechanisms. The exact pathophysiology of AD has not been completely understood, and there are no curative therapies yet. Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a polyphenol that is noted for its antioxidant and anti-inflammatory properties.

OBJECTIVE

To review the role of resveratrol in the pathophysiological aspects of AD.

METHODS

This study carried out a literature review using PubMed/Medline, Virtual Health Library (VHL), Web of Sciences, SCOPUS and the Cochrane Library databases. Original research articles, describing both in vitro and in vivo experiments, published between 2008 and 2018, were included.

RESULTS

We identified 667 articles, of which 619 were excluded because they were repeated or did not follow the inclusion criteria. The present study includes the remaining 48 articles.

DISCUSSION

Resveratrol demonstrates beneficial and protective effects in AD models and seems to provide a promising therapeutic alternative.

CONCLUSION

Although resveratrol appears to mitigate some pathophysiological aspects of AD, further studies are needed to prove the safety and efficacy of this compound in humans.

Apoptotic Inducement of Neuronal Cells by Aluminium Chloride and the Neuroprotective Effect of Eugenol in Wistar Rats

Aluminium is known to accelerate oxidative stress, amyloid beta (Aβ) deposition, and plaque formation in the brain of rats. Objective. The present study is aimed at studying the neuroprotective effects of eugenol following aluminium-induced neurotoxicity on caspase-3, apoptotic proteins (Bcl-2 and Bax), and oxidative stress markers in Wistar rats such as superoxide dismutase (SOD), glutathione peroxidase (GPx), nitric oxide (NO), and assay oxidative stress to mitochondrial DNA (mtDNA) by measuring the levels of 8-hydroxy-2-deoxyguanosine (8-OHdG). Materials and methods. Twenty (20) adult Wistar rats were randomly divided into four (4) groups with five animals in each group. Route of administration was oral throughout the duration of this study and this study lasted for 21 days. Rats were sacrificed 24 hours after administration of the last dose (i.e., day 22) with 0.8 mg/kg ketamine as an anaesthetic agent. Results. Exposure to AlCl₃ resulted in a significant (p < 0.01) elevation in the levels of nitric oxide and 8-hydroxy-2-deoxyguanosine (8-OHdG), enhanced the activity of caspase-3, increased the level of proapoptotic protein Bax and reduced the levels of antiapoptotic protein Bcl-2, and significantly (p < 0.01) reduced the levels of SOD and GPx. However, treatment with eugenol resulted in a significant reduction (p < 0.01) in the levels of nitric oxide (NO) and 8-hydroxy-2-deoxyguanosine (8-OHdG) levels, inhibited the activity of caspase-3, increased levels of Bcl-2 and significantly (p < 0.05) reduced levels of Bax protein, respectively, and also significantly (p < 0.05) increased the levels of SOD and GPx. Our results would hereby suggest that eugenol would provide a therapeutic value against aluminium-induced oxidative stress as related to antioxidant and antiapoptotic activities.

Licochalcone B Ameliorates Liver Cancer via Targeting of Apoptotic Genes, DNA Repair Systems, and Cell Cycle Control

Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a ubiquitous multifunctional protein required in the DNA base excision repair pathway and a noteworthy reducing-oxidizing factor that regulates the activity of various transcription factors. Cyclin-dependent kinases (CDKs) assume a key role in directing the progression of the cell- cycle. The present study evaluated the synergistic efficacy of using licochalcone B (LCB) and fullerene C60 (FnC60) nanoparticles against diethylnitrosamine (DEN)-induced hepatocarcinoma in rats and relevant signaling pathways, with APE1/Ref-1 and CDK-4, as novel anti-cancer- targeting. LCB alone and in combination with FnC60 significantly decreased DNA fragmentation, oxidative DNA damage (8-hydroxy-2'-deoxyguanosine levels), APE1/Ref-1, CDK-4, retinoblastoma, B- cell lymphoma-2 (Bcl-2), B-cell lymphoma-xL (Bcl-xL), and β-arrestin-2 mRNA expression, and APE1/Ref-1 and CDK-4 protein expression. In contrast, these treatments significantly increased the expression of protein 53 (p53), Bcl-2-associated X protein (Bax), and caspase-3. These data suggest that LCB either alone or in combination with FnC60 elicited significant protective effects against DEN-induced hepatocarcinogenesis, which may have occurred because of the regulation of enzymes involved in DNA repair and cell-cycle control at S phase progression as well as the induction of apoptosis at the gene and protein expression levels. Furthermore, FnC60 potentiated the effect of LCB at the molecular level, possibly through targeting of cancerous cells.

Telmisartan Protects Against Aluminum-Induced Alzheimer-like Pathological Changes in Rats

Currently, there is no effective mean for treatment or prevention of Alzheimer's disease (AD). Commonly used AD drugs have a moderate effect and treat only the associated symptoms, therefore there is a strong need to search for more effective agents. Our goal is to examine telmisartan neuroprotective effect in aluminum-induced cognitive impairment in rats. Aluminum chloride (10 mg/kg, i.p) was administered for 2 months then behavioral tests (Y-maze and Morris water maze) were done. Hippocampal biochemical and histological analysis were then carried out. AD-like histological, biochemical, and behavioral alterations appeared in aluminum-treated rats. Telmisartan improved rats' condition on behavioral and histological levels. It reversed the increase in hippocampal amyloid beta protein, phosphorylated tau protein contents together with augmentation of neprilysin level, it also diminished levels of nuclear factor kappa-B, FAS ligand, tumor necrosis factor-alpha, malondialdehyde, and acetylcholinesterase content.These findings show the protective action of telmisartan against AD-like pathological alterations.

Toxic metal(loid)-based pollutants and their possible role in autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social interaction, verbal and non-verbal communication, and stereotypic behaviors. Many studies support a significant relationship between many different environmental factors in ASD etiology. These factors include increased daily exposure to various toxic metal-based environmental pollutants, which represent a cause for concern in public health. This article reviews the most relevant toxic metals, commonly found, environmental pollutants, i.e., lead (Pb), mercury (Hg), aluminum (Al), and the metalloid arsenic (As). Additionally, it discusses how pollutants can be a possible pathogenetic cause of ASD through various mechanisms including neuroinflammation in different regions of the brain, fundamentally occurring through elevation of the proinflammatory profile of cytokines and aberrant expression of nuclear factor kappa B (NF-κB). Due to the worldwide increase in toxic environmental pollution, studies on the role of pollutants in neurodevelopmental disorders, including direct effects on the developing brain and the subjects' genetic susceptibility and polymorphism, are of utmost importance to achieve the best therapeutic approach and preventive strategies.

A Combination of Resveratrol and Curcumin is Effective Against Aluminum Chloride-Induced Neuroinflammation in Rats

BACKGROUND

Experimental studies have demonstrated that aluminum is an environmental toxin that induces neuroinflammation and the development of Alzheimer's disease.

OBJECTIVE

In this report, we investigated the beneficial effect of a combination of resveratrol and curcumin to reduce aluminum-induced neuroinflammation.

METHOD

We employed both an in vivo model of aluminum-induced neuroinflammation and an in vitro aluminum stimulated cultured PC-12 cells. Neuroinflammation in rats was assessed by measuring the expression of β-secretase, amyloid-β protein precursor, and γ-subunits (PS-1 and PS-2), along with the inflammatory COX-2, Il-1β, Il-1α, and TNF-α. Furthermore, we measured the expression profiles of neuro-protective Apurinic/apyrimidinic endonuclease 1 (APE1) protein and let-7c microRNA. In parallel, PC-12 cells were treated with 0.5 mM aluminum to induce a neuroinflammation-like state. In addition, curcumin effect, as a selective COX-2 expression inhibitor, was detected in a time course manner.

RESULTS

An overall significant attenuation of the inflammatory markers, as well as a decrease in the amyloidogenic mediators, was observed in resveratrol-curcumin treated rats. The therapeutic effect was also confirmed by transmission electron microscopic analysis of the brain cortexes. APE1 was significantly induced by resveratrol-curcumin combination. Both in vivo and in vitro studies indicated that Let-7c expression is significantly reduced after aluminum stimulation, an effect that was partially suppressed by co-addition of either resveratrol or curcumin and totally restored to the normal level by their combination.

CONCLUSIONS

The present study clearly indicates the synergistic and therapeutic effect of a  resveratrol-curcumin combination. We also show that both compounds exert beneficial effect either cooperatively or through differential molecular mechanisms in counteracting aluminum-induced neuroinflammation.

Curcumin revitalizes Amyloid beta (25-35)-induced and organophosphate pesticides pestered neurotoxicity in SH-SY5Y and IMR-32 cells via activation of APE1 and Nrf2

Amyloid beta (Aβ) peptide deposition is the primary cause of neurodegeneration in Alzheimer's disease (AD) pathogenesis. Several reports point towards the role of pesticides in the AD pathogenesis, especially organophosphate pesticides (OPPs). Monocrotophos (MCP) and Chlorpyrifos (CP) are the most widely used OPPs. In this study, the role of MCP and CP in augmenting the Aβ-induced oxidative stress associated with the neurodegeneration in AD has been assessed in human neuroblastoma IMR-32 and SH-SY5Y cell lines. From the cell survival assay, it was observed that MCP and CP reduced cell survival both dose- and time-dependently. Nitro blue tetrazolium (NBT) based assay for determination of intracellular reactive oxygen species (ROS) demonstrated that Aβ(25-35), MCP or CP produce significant oxidative stress alone or synergistically in IMR-32 and SH-SY5Y cells, while pretreatment of curcumin reduced ROS levels significantly in all treatment combinations. In this study, we also demonstrate that treatment of Aβ(25-35) and MCP upregulated inducible nitric oxide synthase (iNOS/NOS2) whereas, no change was observed in neuronal nitric oxide synthase (nNOS/NOS1), but down-regulation of the nuclear factor erythroid 2-related factor 2 (Nrf2) level was observed. While curcumin pretreatment resulted in upregulation of iNOS and Nrf2 proteins. Also, the expression of key DNA repair enzymes APE1, DNA polymerase beta (Pol β), and PARP1 were found to be downregulated upon treatment with MCP, Aβ(25-35) and their combinations at 24 h and 48 h time points. In this study, pretreatment of curcumin to the SH-SY5Y cells enhanced the expression of DNA repair enzymes APE1, pol β, and PARP1 enzymes to counter the oxidative DNA base damage via base excision repair (BER) pathway, and also activated the antioxidant element (ARE) via Nrf2 upregulation. Furthermore, the immunofluorescent confocal imaging studies in SH-SY5Y and IMR-32 cells treated with Aβ(25-35) and MCP-mediated oxidative stress and their combinations at different time periods suggesting for cross-talk between the two proteins APE1 and Nrf2. The APE1's association with Nrf2 might be associated with the redox function of APE1 that might be directly regulating the ARE-mediated neuronal survival mechanisms.

Neuroprotective effects of eugenol against aluminiuminduced toxicity in the rat brain

Aluminium (Al) is a neurotoxic metal that contributes to the progression of several neurodegenerative diseases. The aim of the present study was to evaluate the protective effect of dietary eugenol supplementation against aluminium (Al)- induced cerebral damage in rats. Male Wistar rats were divided into four groups: normal controls, rats fed a diet containing 6,000 μg g-1 eugenol, rats intoxicated daily with aluminium chloride (84 mg kg-1 body weight) p. o. and fed either a basal diet or a eugenol-containing diet. Daily oral administration of Al for four consecutive weeks to rats significantly reduced brain total antioxidant status (TAS) (11.42±0.31 μmol g-1 tissue, p<0.001) with a subsequent significant enhancement of lipid peroxidation (MDA) (32.55±1.68 nmol g-1 tissue, p<0.002). In addition, Al enhanced brain acetylcholinesterase activity (AChE) (46.22±4.90 U mg-1 protein, p<0.001), tumour necrosis factor alpha (TNF-α) (118.72±11.32 pg mg-1 protein, p<0.001), and caspase 3 (Casp-3) (8.77±1.26 ng mg-1 protein, p<0.001) levels, and in contrast significantly suppressed brain-derived neurotrophic factor (BDNF) (82.74±14.53 pg mg-1 protein, p<0.002) and serotonin (5-HT) (1.54±0.12 ng mg-1 tissue, p<0.01) levels. Furthermore, decreased glial fibrillary acidic protein (GFAP) immunostaining was noticed in the striatum of Al-intoxicated rats, compared with untreated controls. On the other hand, co-administration of dietary eugenol with Al intoxication restored brain BDNF (108.76±2.64 pg mg-1 protein) and 5-HT (2.13±0.27 ng mg-1 tissue) to normal levels, enhanced brain TAS (13.43±0.24 μmol g-1 tissue, p<0.05), with a concomitant significant reduction in TNF-α (69.98±4.74 pg mg-1 protein) and Casp-3 (3.80±0.37 ng mg-1 protein) levels (p<0.001), as well as AChE activity (24.50±3.25 U mg-1 protein, p<0.001), and increased striatal GFAP immunoreactivity, compared with Al-treated rats. Histological findings of brain tissues verified biochemical data. In conclusion, eugenol holds potential as a neuroprotective agent through its hydrophobic, antioxidant, and anti-apoptotic properties, as well as its neurotrophic ability against Al-induced brain toxicity in rats.

Apurinic/apyrimidinic endonuclease 1 (APE1) contributes to resveratrol‑induced neuroprotection against oxygen‑glucose deprivation and re‑oxygenation injury in HT22 cells: Involvement in reducing oxidative DNA damage

Resveratrol, a naturally occurring polyphenolic compound, exhibits a neuroprotective role in models of central nervous system diseases, including cerebral ischemia/reperfusion injury. Apurinic/apyrimidinic endonuclease 1 (APE1) is a multifunctional enzyme that contributes to base excision repair of oxidative DNA damage and redox activation of transcription factors, associated with neuronal survival against hypoxic‑ischemic injury. It was hypothesized that resveratrol protects HT22 cells against oxygen‑glucose deprivation and re‑oxygenation (OGD/R)‑induced injuries through upregulation of APE1. It was demonstrated that resveratrol pretreatment significantly increased the viability of HT22 cells and decreased the release of lactate dehydrogenase (LDH), accompanied by the upregulation of APE1 mRNA, and protein levels, as well as the activity of APE1 under OGD/R conditions. In addition, resveratrol reversed OGD/R‑induced oxidative DNA damage as evidenced by the decreases in the levels of 8‑hydroxy‑2'‑deoxyguanosine and APE sites. However, APE1 knockdown using short hairpin RNA sequence targeting APE1 abolished resveratrol‑elicited beneficent effects against OGD/R‑induced cytotoxicity and oxidative stress. This was indicated by decreased cell viability, superoxide dismutase activity and glutathione levels, and increased LDH release and reactive oxygen species levels. The results of the present study indicate that APE1 contributes to the protective effects of resveratrol against neonatal hypoxic‑ischemic brain injuries, and suggest that DNA repair enzymes, including APE1, may be a unique strategy for neuroprotection against this disease.

The putative role of environmental aluminium in the development of chronic neuropathology in adults and children. How strong is the evidence and what could be the mechanisms involved?

The conceptualisation of autistic spectrum disorder and Alzheimer's disease has undergone something of a paradigm shift in recent years and rather than being viewed as single illnesses with a unitary pathogenesis and pathophysiology they are increasingly considered to be heterogeneous syndromes with a complex multifactorial aetiopathogenesis, involving a highly complex and diverse combination of genetic, epigenetic and environmental factors. One such environmental factor implicated as a potential cause in both syndromes is aluminium, as an element or as part of a salt, received, for example, in oral form or as an adjuvant. Such administration has the potential to induce pathology via several routes such as provoking dysfunction and/or activation of glial cells which play an indispensable role in the regulation of central nervous system homeostasis and neurodevelopment. Other routes include the generation of oxidative stress, depletion of reduced glutathione, direct and indirect reductions in mitochondrial performance and integrity, and increasing the production of proinflammatory cytokines in both the brain and peripherally. The mechanisms whereby environmental aluminium could contribute to the development of the highly specific pattern of neuropathology seen in Alzheimer's disease are described. Also detailed are several mechanisms whereby significant quantities of aluminium introduced via immunisation could produce chronic neuropathology in genetically susceptible children. Accordingly, it is recommended that the use of aluminium salts in immunisations should be discontinued and that adults should take steps to minimise their exposure to environmental aluminium.

The role of intestinal endotoxemia in a rat model of aluminum neurotoxicity

The present study aimed to investigate the effects of intestinal endotoxemia (IETM) in a rat model of aluminum neurotoxicity established by D-galactose and aluminum trichloride (AlCl3). Adult Wistar rats were administered D‑galactose and AlCl3 to create the aluminum neurotoxicity model. The learning and memory abilities of the rats were subsequently observed using a Morris water maze test and the serum levels of lipopolysaccharide (LPS), tumor necrosis factor (TNF)‑α, interleukin (IL)‑1, diamine oxidase (DAO), glutamine (Gln) and glutaminase were measured. The expression of S‑100β in the serum was detected using an enzyme‑linked immunosorbent assay. The expression levels of the amyloid β‑protein (Aβ) precursor (APP), presenilin 1 (PS1), β‑site APP‑cleaving enzyme (BACE), zona occludens protein (ZO)‑1 and Aβ 1‑40 in the brain of rats were detected via reverse‑transcription polymerase chain reaction, western blotting and immunohistochemistry. The levels of LPS, TNF‑α, IL‑1, DAO, Gln and S‑100β in serum and the mRNA and protein expression levels of APP, PS1, BACE and Aβ1‑40 in the brain were markedly increased in the model rats compared with controls. The level of glutaminase in the serum and the expression of ZO‑1 in the brain were decreased in the model rats compared with controls. IETM was present in the rat model of aluminum neurotoxicity established by D‑galactose and AlCl3 and may be important in the development of this neurotoxicity.

Aluminum-induced molecular neurodegeneration: The protective role of genistein and chickpea extract

Neurotoxicity of Al is well established and linked to oxidative damage and neurodegeneration. This study investigated the protective role of genistein (Gen) and chickpea extract (CPE) against AlCl₃-induced neurodegeneration. HPLC analysis revealed that biochanin A-7-O-β-D-glucoside and biochanin A are the major components of the CPE. Gene expression of TNF-α, APP, BACE1, PSEN-2 and ER-β were assessed in brain extract using RT-PCR. Also, NF-кB subunit P65 and COX-2 expression were evaluated by western blotting. The cholinergic function, histological examination and oxidative status were also estimated. The AlCl₃ significantly up regulated the expression of the NF-кB subunit P65, COX-2, TNF- α, BACE1and APP while it significantly down regulated PSEN-2 and ER-β expression. The activity of acetyl cholinesterase (AChE) and the oxidative stress parameters as well as the histological examination confirmed the deleterious effect of AlCl₃. The administration of either CPE or Gen attenuated the expression of inflammatory cytokines, inhibited the amyloidogenesis and restored both the AChE activity and ER-β expression. Gen and CPE also inhibited the oxidative stress and ameliorated the histological alterations. Accordingly, the present study provides an insight on the molecular role of Gen and CPE as protective agents against neuronal injury.

Resveratrol prevents ammonia-induced mitochondrial dysfunction and cellular redox imbalance in C6 astroglial cells

BACKGROUND

Resveratrol is a polyphenolic compound that presents several protective effects in the central nervous system, including gliotoxicity associated to hyperammonemia, a key element for the development of hepatic encephalopathy. In this condition, mitochondrial dysfunction leads to a reactive oxygen species (ROS) overproduction, which, in turn, exacerbates mitochondrial failure and causes cellular damage.

OBJECTIVE

This study sought to determine whether prevention of mitochondrial dysfunction and the maintenance of cellular redox status by resveratrol contribute to its protective action toward ammonia toxicity.

METHODS

C6 astrocyte cell line was pre-incubated in the presence or absence of resveratrol (100 μM) for 1 hour. After pre-incubation, resveratrol was maintained and 5 mM ammonia was added for 24 hours, followed by the evaluation of ROS production, mitochondrial functionality, antioxidant enzymatic and non-enzymatic defenses, energy metabolic parameters, and genotoxicity.

RESULTS

We showed that resveratrol prevented the increase in ROS production, the decrease of mitochondrial membrane potential (ΔΨ_m), and bioenergetics deficit caused by ammonia in C6 astroglial cells. In addition, resveratrol avoided the ammonia-induced upregulation of NOX activity and impairment in enzymatic and non-enzymatic antioxidant defenses. Ammonia also induced DNA damage that was prevented by resveratrol, indicating its genoprotective effect.

CONCLUSIONS

In summary, our study demonstrates that resveratrol prevents ammonia-induced cytotoxicity, as well as supports the role of resveratrol on mitochondrial/cellular redox functionality.

The anti-inflammatory role of extranuclear apurinic/apyrimidinic endonuclease 1/redox effector factor-1 in reactive astrocytes

Apurinic/apyrimidinic endonuclease 1 (APE1), a ubiquitous multipurpose protein, is also known as redox effector factor-1 (Ref-1). It is involved in DNA repair and redox signaling and, in turn, oxidative stress-induced neurodegeneration. Although previous studies have demonstrated that APE1/Ref-1 functions as a negative regulator of inflammatory response via several mechanisms in neuronal cells, little is known about the roles of APE1/Ref-1 in glial cells. In this study, we found that cytoplasmic APE1/Ref-1 expression was upregulated in reactive astrocytes of the kainic acid- or lipopolysaccharide (LPS)-injected hippocampus. Analysis of the inflammatory response induced by extranuclear APE1/Ref-1 (ΔNLS-Ref-1) in cultured primary astrocytes revealed that it markedly suppressed inducible nitric oxide synthase (iNOS) expression and tumor necrosis factor-α (TNF-α) secretion induced by LPS to a similar extent as did wild type APE1/Ref-1 (WT-Ref-1), supporting the concept an anti-inflammatory role of extranuclear APE1/Ref-1 in astrocytes. Additionally, overexpression of WT- and ΔNLS-Ref-1 suppressed the transcriptional activity of nuclear factor-κB (NF-κB), although it effectively enhanced activator protein 1 (AP-1) activity. The blunting effect of APE1/Ref-1 on LPS-induced NF-κB activation was not mediated by IκB kinase (IKK) activity. Instead, APE1/Ref-1 inhibited p300-mediated acetylation of p65 by suppressing intracellular reactive oxygen species (ROS) levels following LPS treatment. Taken together, our results showed that altered expression and/or subcellular distribution of APE1/Ref-1 in activated astrocytes regulated the neuroinflammatory response to excitotoxin and endotoxin insults used in model of neurodegenerative brain diseases.

Aluminum chloride induces neuroinflammation, loss of neuronal dendritic spine and cognition impairment in developing rat

Aluminum (Al) is present in the daily life of humans, and the incidence of Al contamination increased in recent years. Long-term excessive Al intake induces neuroinflammation and cognition impairment. Neuroinflammation alter density of dendritic spine, which, in turn, influence cognition function. However, it is unknown whether increased neuroinflammation is associated with altered density of dendritic spine in Al-treated rats. In the present study, AlCl3 was orally administrated to rat at 50, 150 and 450 mg/kg for 90d. We examined the effects of AlCl3 on the cognition function, density of dendritic spine in hippocampus of CA1 and DG region and the mRNA levels of IL-1β, IL-6, TNF-α, MHC II, CX3CL1 and BNDF in developing rat. These results showed exposure to AlCl3 lead to increased mRNA levels of IL-1β, IL-6, TNF-α and MCH II, decreased mRNA levels of CX3CL1 and BDNF, decreased density of dendritic spine and impaired learning and memory in developing rat. Our results suggest AlCl3 can induce neuroinflammation that may result in loss of spine, and thereby leads to learning and memory deficits.

Protective effect of transient receptor potential vanilloid subtype 1 (TRPV1) modulator, against behavioral, biochemical and structural damage in experimental models of Alzheimer's disease

Alzheime's disease (AD) is an overwhelming neurodegenerative disorder, characterized by synaptic dysfunction, memory loss, neuro-inflammation and neural cell death. Very few treatments are in hand for the management of AD and they are only concentrating on peculiar aspects. Hence, an immense thrust is required to find utmost therapeutic targets to conquer this condition. This study investigates a potential role of vanillin, a selective agonist of transient receptor potential vanilloid subtype 1 (TRPV1) in the experimental models of AD viz. intracerebroventricular (i.c.v.) streptozotocin (STZ) and aluminum trichloride (AlCl3)+d-galactose induced AD in mice. The i.c.v. administration of STZ and intraperitoneally administration of AlCl3+d-galactose have significantly impaired learning-memory (Morris water maze and attentional set-shifting test), brain structure (hematoxylin, eosin and Congo red staining), enhanced brain oxidative stress (thiobarbituric acid reactive substance - TBARS and glutathione - GSH), nitrosative stress (nitrite/nitrate), acetylcholinesterase activity (AChE), inflammation (MPO), and calcium levels (Ca(++)). Treatment with vanillin in different doses and donepezil have significantly ameliorated i.c.v. STZ and AlCl3+d-galactose induced reduction in executive function, impaired reversal learning, cognition, memory and brain damage. Treatment with these drugs has also reduced the brain oxidative stress (TBARS and GSH), nitrosative stress (nitrite/nitrate), and AChE, MPO, and Ca(++) levels. These results indicate that vanillin, a selective agonist of TRPV1 and donepezil, a potent acetylcholine esterase inhibitor have attenuated i.c.v. STZ and AlCl3+d-galactose induced experimental AD. Hence, pharmacological positive modulation of TRPV1 channels may be a potential research target for mitigation of AD.

Ibuprofen targets neuronal pentraxins expresion and improves cognitive function in mouse model of AlCl3-induced neurotoxicity

Aluminum is known to exert neurotoxic effects associated with various neurodegenerative disorders, including Alzheimer's disease (AD). Ibuprofen is a well-known non-steroidal anti-inflammatory drug, which has demonstrated potential efficacy in the treatment of numerous inflammatory and neurodegenerative disorders, including AD. The present study aimed to investigate the protective effects of ibuprofen on cognitive function, and the expression levels of neuronal pentraxins (NPs) and interleukin (IL)-1β in an aluminum chloride (AlCl₃)-induced mouse model of neurotoxicity. The effects of ibuprofen (100 mg/kg/day for 12 days) on learning and memory were evaluated in the AlCl₃-induced neurotoxic mice using a Morris water maze and open field tests. In addition, ibuprofen was assessed for its effects on the expression levels of NPs and IL-1β in the hippocampus, cortex and amygdala of the brain. Treatment of the AlCl₃-treated mice with ibuprofen decreased anxiety levels (6.90±0.34 min) compared with the AlCl₃-treated group (1.80±0.29 min), as indicated by the time spent in the central area in an open field test. Furthermore, the expression levels of NP1 (1.32±0.47) and IL-1β (0.99±0.21) were significantly decreased in the hippocampus of mice following ibuprofen treatment, as compared with the AlCl₃-treated mice (8.62±1.54 and 7.47±0.53, respectively). In the present study, ibuprofen was able to target novel structures in order to attenuate the inflammation associated with an AlCl₃-induced mouse model of neurotoxicity; thus suggesting that ibuprofen may be considered a potential therapeutic option for the treatment of neurodegenerative diseases, including AD.

Lactobacillus plantarum CCFM639 alleviates aluminium toxicity

Aluminium (Al) is the most abundant metal in the earth's crust. Al exposure can cause a variety of adverse physiological effects in humans and animals. Our aim was to demonstrate that specific probiotic bacteria can play a special physiologically functional role in protection against Al toxicity in mice. Thirty strains of lactic acid bacteria (LAB) were tested for their aluminium-binding ability, aluminium tolerance, their antioxidative capacity, and their ability to survive the exposure to artificial gastrointestinal (GI) juices. Lactobacillus plantarum CCFM639 was selected for animal experiments because of its excellent performance in vitro. Forty mice were divided into four groups: control, Al only, Al plus CCFM639, and Al plus deferiprone (DFP). CCFM639 was administered at 10(9) CFU once daily for 10 days, followed by a single oral dose of aluminium chloride hexahydrate at 5.14 mg aluminium (LD50) for each mouse. The results showed that CCFM639 treatment led to a significant reduction in the mortality rates with corresponding decrease in intestinal aluminium absorption and in accumulation of aluminium in the tissues and amelioration of hepatic histopathological damage. This probiotic treatment also resulted in alleviation of hepatic, renal, and cerebral oxidative stress. The treatment of L. plantarum CCFM639 has potential as a therapeutic dietary strategy against acute aluminium toxicity.

Pharmacological benefits of selective modulation of cannabinoid receptor type 2 (CB2) in experimental Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that pervasively affects the population across the world. Currently, there is no effective treatment available for this and existing drugs merely slow the progression of cognitive function decline. Thus, massive effort is required to find an intended therapeutic target to overcome this condition. The present study has been framed to investigate the ameliorative role of selective modulator of cannabinoid receptor type 2 (CB2), 1-phenylisatin in experimental AD condition. We have induced experimental AD in mice by using two induction models viz., intracerebroventricular (i.c.v.) administration of streptozotocin (STZ) and aluminum trichloride (AlCl3)+d-galactose. Morris water maze (MWM) and attentional set shifting test (ASST) were used to assess learning and memory. Hematoxylin-eosin and Congo red staining were used to examine the structural variation in brain. Brain oxidative stress (thiobarbituric acid reactive substance and glutathione), nitric oxide levels (nitrites/nitrates), acetyl cholinesterase activity, myeloperoxidase and calcium levels were also estimated. i.c.v. STZ as well as AlCl3+d-galactose have impaired spatial and reversal learning with executive functioning, increased brain oxidative and nitrosative stress, cholinergic activity, inflammation and calcium levels. Furthermore, these agents have also enhanced the burden of Aβ plaque in the brain. Treatment with 1-phenylisatin and donepezil attenuated i.c.v. STZ as well as AlCl3+d-galactose induced impairment of learning-memory, brain biochemistry and brain damage. Hence, this study concludes that CB2 receptor modulation can be a potential therapeutic target for the management of AD.

Fractionated Radiation Exposure of Rat Spinal Cords Leads to Latent Neuro-Inflammation in Brain, Cognitive Deficits, and Alterations in Apurinic Endonuclease 1

Ionizing radiation causes degeneration of myelin, the insulating sheaths of neuronal axons, leading to neurological impairment. As radiation research on the central nervous system has predominantly focused on neurons, with few studies addressing the role of glial cells, we have focused our present research on identifying the latent effects of single/ fractionated -low dose of low/ high energy radiation on the role of base excision repair protein Apurinic Endonuclease-1, in the rat spinal cords oligodendrocyte progenitor cells’ differentiation. Apurinic endonuclease-1 is predominantly upregulated in response to oxidative stress by low- energy radiation, and previous studies show significant induction of Apurinic Endonuclease-1 in neurons and astrocytes. Our studies show for the first time, that fractionation of protons cause latent damage to spinal cord architecture while fractionation of HZE (²⁸Si) induce increase in APE1 with single dose, which then decreased with fractionation. The oligodendrocyte progenitor cells differentiation was skewed with increase in immature oligodendrocytes and astrocytes, which likely cause the observed decrease in white matter, increased neuro-inflammation, together leading to the observed significant cognitive defects.

Protective effect of chronic caffeine intake on gene expression of brain derived neurotrophic factor signaling and the immunoreactivity of glial fibrillary acidic protein and Ki-67 in Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder with progressive degeneration of the hippocampal and cortical neurons. This study was designed to demonstrate the protective effect of caffeine on gene expression of brain derived neurotrophic factor (BDNF) and its receptor neural receptor protein-tyrosine kinase-β (TrkB) as well as glial fibrillary acidic protein (GFAP) and Ki-67 immunoreactivity in Aluminum chloride (AlCl3) induced animal model of AD. Fifty adult rats included in this study were classified into 5 group (10 rats each); negative and positive control groups (I&II), AD model group (III), group treated with caffeine from the start of AD induction (IV) and group treated with caffeine two weeks before AD induction (V). Hippocampal tissue BDNF and its receptor (TrkB) gene expression by real time RT-PCR in addition to immunohistochemical study of GFAP and Ki67 immunoreactivity were performed for all rats in the study. The results of this study revealed that caffeine has protective effect through improving the histological and immunohistochemical findings induced by AlCl3 as well as BDNF and its receptor gene expression. It could be concluded from the current study, that chronic caffeine consumption in a dose of 1.5 mg/kg body weight daily has a potentially good protective effect against AD.

The Mechanism of Memory Enhancement of Acteoside (Verbascoside) in the Senescent Mouse Model Induced by a Combination of D-gal and AlCl3

Acteoside (verbsacoside), one of the main active phenylethanoid glycosides from Cistanche deserticola, is known to have antioxidant and neuroprotective activity, and herbs containing it are used to enhance memory. However, there is relatively little direct experimental evidence to support the use of acteoside in Alzheimer's disease (AD). The purpose of this study was to elucidate the effects of acteoside in improving learning and memory, using a mouse model of senescence induced by a combination of d-galactose and AlCl3 , and investigate its potential mechanisms compared with the positive controls vitamin E and piracetam. Acteoside was administered intragastrically at doses of 30, 60 and 120 mg/kg/day for 30 days after AD was induced. Memory function was evaluated using a step-down test. The number of neuron was analysed by haematoxylin and eosin staining and the number of Nissl bodies by Nissl staining. The expression of caspase-3 protein in hippocampus was detected by immunohistochemistry and western blot. Nitric oxide and total nitric oxide synthase level in hippocampus were also assessed. Our results showed that the latency of step down was shortened in AD model mice and the number of errors decreased after treatment with all doses of acteoside. Neurons and Nissl bodies in the hippocampus were increased significantly with higher doses (60 and 120 mg/kg/day) of acteoside. The content of nitric oxide, the activity of nitric oxide synthase and the expression of caspase-3 protein were decreased by 120 mg/kg/day acteoside compared with that of the AD model group. Our results support the results obtained previously using the Morris maze test in the same mouse model of senescence, and the use of traditional medicinal herbs containing acteoside for neuroprotection and memory loss.

The protective properties of melatonin against aluminium-induced neuronal injury

Aluminium (Al) toxicity is closely linked to the pathogenesis of Alzheimer's disease (AD). This experimental study investigated the neuroprotective effect of melatonin (Mel; 10 mg/kg bwt) on aluminium chloride (AlCl3 ; 34 mg/kg bwt) induced neurotoxicity and oxidative stress in rats. Adult male albino Wistar rats were injected with AlCl3 for 7 days. The effect on brain structure, lipid peroxidation (LPO), nitric oxide (NO) levels, glutathione (GSH) content, antioxidant enzymes (SOD, CAT, GPx and GR), apoptotic proteins (Bax and Bcl-2) and an apoptotic enzyme (caspase-3) was investigated. No apparent changes occurred following the injection of melatonin. Melatonin pretreatment of the AlCl3 -administered rats reduced brain damage, and the tissues appeared like those of the control rats. Compared to treatment with AlCl3 , pretreatment with melatonin decreased LPO and NO levels and increased the GSH content and antioxidant enzyme activity. Moreover, melatonin increased the levels of the anti-apoptotic protein, Bcl-2, decreased the levels of the pro-apoptotic protein, Bax, and inhibited caspase-3 activity. Therefore, our results indicate that melatonin may provide therapeutic value against aluminium-induced oxidative stress and histopathological alternations in the rat brain and that these effects may be related to anti-apoptotic and antioxidant activities.