Effects of vitamin E against aluminum neurotoxicity in rats

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

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

Natural antioxidants enhance the power of physical and mental activities versus risk factors inducing progression of Alzheimer's disease in rats

BACKGROUND

Alzheimer's disease (AD) is a progressive neurodegenerative disease that is exacerbated by social isolation (SI) and protein malnutrition (PM). Antioxidants, physical and mental activities (Ph&M) can maintain cognitive functions and protect against dementia.

OBJECTIVE

To investigate the impact of Epigallocatechin-3-gallate (EGCG), Vitamin E (VE), Vitamin C (VC), and Selenium (Se), in enhancing the potential effect of Ph&M versus SI&PM as risk factors in the progression of AD in rats.

METHODS

Aluminum chloride (70 mg/kg, I.P for 5 weeks) was used to induce AD in rats that either normally fed or socially isolated and protein malnourished (SI&PM). Simultaneously, rats were weekly exposed to Ph&M either alone or in combination with EGCG (10 mg/kg, I.P), VC (400 mg/kg, P.O), VE (100 mg/kg, P.O), and Se (1 mg/kg, P.O).

RESULTS

The combination protocol of EGCG, VE, VC, and Se together with Ph&M significantly increased brain monoamines, superoxide dismutase (SOD), total antioxidant capacity (TAC) and brain-derived neurotrophic factor (BDNF) in AD, SI&PM and SI&PM/AD groups. Additionally, this regimen significantly mitigated brain acetylcholine esterase (ACHE), β-amyloid (Aβ), Tau protein, β-secretase, malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), and Interleukin 1β (IL-1β) as well as DNA fragmentation. These biochemical findings were supported by the histopathological examinations of brain tissue.

CONCLUSION

The combination protocol of antioxidants with Ph&M activities mitigated SI&PM-induced progressive risk of AD.

[Reactive changes in morphological and morphometric parameters of immunopositive astrocytes of the amygdala in response to hormone level in absence epilepsy]

AIM

To study the changes in the morphological and morphometric parameters of immunopositive astrocytes of the amygdala in absence epilepsy depending on hormonal profile.

MATERIAL AND METHODS

Adult female WAG/Rij rats were used as experimental subjects. The astrocytes were detected on serial sections using a reaction to glial fibrillary acidic protein (GFAP) with pre-stained hematoxylin. Quantitative analysis was carried out for a 204.8´153.6 μm² field of view.

RESULTS

In the control group, astrocytes had a relatively regular stellate form and GFAP was moderately expressed in their bodies and processes. The number of astrocytes was 18.20±2.87, and their area was 164±3.29 μm². After ovariectomy, a high expression of the protein, both in the bodies and in the processes of astrocytes, increasing the cell size to 188.85±4.97 μm² (p<0.05) was observed. The astrocytes increased to 34.55±3.03 (p<0.05). In addition, the deformation of the processes and their diffuse defibration were observed. After hormone replacement therapy, a decrease in GFAP expression was detected, the area of astrocytes became smaller in comparison with the group after ovariectomy: 173.54±5.48 μm² (p<0.05). Morphological changes in glial cells were manifested as a decrease in the size of their bodies, the processes became smooth without diffuse sprouting and swelling, which is probably associated with neuroprotective functions of estradiol.

CONCLUSION

Thus, the results of our study demonstrated that the deficiency of female sex hormones led to the increase in both the amount and area of astrocytes in the anterior cortical nucleus of the amygdala, and hormone replacement therapy positively affected the structural and quantitative characteristics of astrocytes due to the endogenous protective role of estradiol.

Oral exposure to aluminum leads to reduced nicotinic acetylcholine receptor gene expression, severe neurodegeneration and impaired hippocampus dependent learning in mice

Aluminum (Al) is known for its neurotoxicity for over a century and is reported to have specifically high toxicity for cholinergic system. The effect of Al on muscarinic acetylcholine receptors is widely reported, but its effect on nicotinic acetylcholine receptors (nAChRs) is less well known. The aim of this study was to determine the effects of Al on hippocampus dependent learning and memory, function and expression of nAChRs in the hippocampus. Al concentration and neurodegeneration were also measured in the hippocampus following Al treatment. The mice were treated with 250 mg/kg AlCl₃.6H₂O in drinking water for a period of 42 days. Results show that Al treated animals have significantly reduced spatial reference memory as compared to control animals in Morris water maze test. Similarly, Al treated animals showed reduced contextual memory for Pavlovian fear compared to control animals. Al treated animals show higher anxiety in elevated plus maze as compared to control animals. The analysis of nAChR expression via RT-PCR showed reduced expression of α7, α4 and β2 nAChR gene expression in the hippocampus of Al treated animals. High Al accumulation was observed in Al-treated animals (688.14 ± 242.82 μg/g) compared to the control group (115.14 ± 18.18 μg/g) that resulted in severe neurodegeneration in the hippocampus. These results demonstrated that Al exposure caused neurotoxicity in mice hippocampus which is manifested by reduced memory and elevated anxiety. The results were further validated by high Al accumulation in the hippocampus, severe neurodegeneration and reduced expression of nAChRs.

Sublethal doses of copper sulphate initiate deregulation of glial cytoskeleton, NF-kB and PARP expression in Capoeta umbla brain tissue

Copper sulphate pentahydrate (CuSO4∙5H2O) is widely used as a pesticide not only in agricultural but in aquaculture farming as well. Copper sulphate is a cheap chemical and able to contaminate the environment, especially water sources, which is crucial for fish harvesting and farming. The copper contamination in some areas is caused over decades because this pesticide has long been used everywhere. Copper ions inhibit invasive aquatic plants and many microorganisms but contaminate soil and natural water resources. The family of copper-containing chemicals is frequently used as algaecides in swimming pools. Despite the high toxicity of copper ions for fish in freshwater ponds, copper sulphate remains one of the prevalent pesticides in fish farming everywhere. High cytotoxicity and accumulation of the copper ions in sediments require study and calculation of the optimal dosage for its use as an antiseptic agent which will not have a detrimental effect on various tissue types of aquatic organisms. The main recognized mechanism which accompanies the toxic effect of copper ions is the generation of oxidative stress. Neural tissue cells are extremely susceptible to oxidative damage and the functions of the CNS are critical to the vitality of organisms. Glial cells maintain the structure and many vital functions of neurons. The cytoskeleton glial fibrillary acidic protein (GFAP), transcriptional nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) and Poly(ADP-ribose) polymerase (PARP) are critical participants in a cellular response to a toxic agent impact. As this takes place, it could be applied in biomarking of heavy metal toxicity. In the presented study, we investigated the effects of copper ions on PARP, NF-kB, and GFAP expression in the Tigris scraper Capoeta umbla brain tissue. For 96 hours the fish were exposed to copper sulphate at sublethal concentrations, namely 1/2, 1/4 and 1/8 of the LD50 value. Western blot analysis of GFAP and PARP was used to assess further effects in the brain tissue. Every studied dose of copper significantly downregulated the expression of GFAP after 72 hours of treatment. In spite of the common increment in the GFAP content, 48 hours exposure to copper initiated the upregulation of that cytoskeleton marker. Moreover, treatment with copper sulphate induced several changes in the β-actin level, especially in the fish group treated for 72 hours. The observed effect of copper in the fish brain evidences the unspecific toxic effect of the copper ions in the brain tissue cells. The obtained results demonstrated meaningful disturbance in the expression of transcriptional factor NF-kB in the brain of the fish group exposed to copper. The changes found in the fish brain indicate the dose-dependent effect in a concentration range 185–740 µg/L of copper sulphate during 72 hours. However, the exposure to low dose of copper ions showed no effect in the fish group treated for 24 hours. Comparative analyses of the PARP content in the brain of fish exposed to copper for 72 hours was significantly less than in the groups treated with copper for both 24 and 48 hours. Thus, the copper ions in the dose range 185–740 µg/L can suppress PARP expression in a time-dependent manner. The results showed that copper ions could induce astroglial response accompanied by modulations of NF-kB and PARP-1 expression. The data obtained in this study suggest that copper sulphate has a significant effect on astrogliosis and DNA damage in the fish brain.

The possible neuroprotective effects of melatonin in aluminum chloride-induced neurotoxicity via antioxidant pathway and Nrf2 signaling apart from metal chelation

Aluminum (Al) had well-identified adverse influences on the nervous system mainly through the creation of reactive oxygen species (ROS). Melatonin works as an antioxidant through the inhibition of ROS and attenuating peroxidation of lipids. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a pivotal transcription factor which controls the transcription of antioxidant enzymes. This study was conducted to determine the potential neuroprophylactic impacts of melatonin in aluminum chloride (AlCl₃)-initiated neurotoxicity including potential mechanism(s) of action and relevant signaling in rats. Thirty-six male rats were distributed into 4 groups: Control; AlCl₃ (50 mg/kg bwt, i.p, 3 times weekly for 3 months); melatonin (5 mg/kg bwt, i.p daily for 2 weeks before AlCl₃ and sustained for the next 3 months); and melatonin with AlCl₃. Neuronal alterations were histopathologically and biochemically evaluated. The neuronal antioxidant-related genes and relevant Nrf2 protein expression were determined by real-time PCR and Western blotting, respectively. The current data showed a substantial increase in brain damage biomarkers, acetylecholinesterase (AchE) activity, and malondialdehyde (MDA) content while the enzymatic antioxidant expression as glutathione-s-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) were substantially attenuated in the aluminum-treated group, with cleared histopathological changes as inflammatory cell infiltration with neuronal degeneration. Supplementation of melatonin resulted in an obvious amelioration in all previous abnormal alteration observed in AlCl₃-treated rats rather than increased Al burden and/or altered Fe and Cu homeostasis with upregulating both total and phosphorylated Nrf2 expression. Therefore, the study concluded that melatonin has a potential ability to be neuroprophylactic against Al-induced neurotoxic effect and oxidative damage in the rat brain through upregulating and instigating Nrf2 signaling apart from metal chelation.

Investigation of the role of α-lipoic acid on fatty acids profile, some minerals (zinc, copper, iron) and antioxidant activity against aluminum-induced oxidative stress in the liver of male rats

BACKGROUND

We have investigated the effects of α-lipoic acid (LA), a powerful antioxidant, on the fatty acid (FA) profiles, aluminum accumulation, antioxidant activity and some minerals such as zinc, copper and iron against aluminum chloride (AlCl3)-induced oxidative stress in rat liver.

METHODS

Twenty-eight male Wistar rats were divided into four groups as control, LA, AlCl3 and LA+AlCl3. For 30 days, LA was intraperitoneally administrated (50 mg/kg) and AlCl3 was given via orogastric gavage (1600 ppm) every other day.

RESULTS

AlCl3-treated animals exhibited higher hepatic malondialdehyde concentration and lower glutathione peroxidase and catalase activity, whereas these alterations were restored by the LA supplementation. Total saturated FA of the AlCl3-treated group was higher than the LA supplementation groups. Moreover, total unsaturated FA level of the LA+AlCl3 group was higher than the AlCl3-treated group. Hepatic zinc level of the AlCl3-treated group was lower than the control group, whereas it was higher in the LA and the LA+AlCl3 groups. Hepatic copper levels did not significantly change in the experimental groups. Iron level was lower in the LA and LA+AlCl3 groups compared with the AlCl3-treated group. Moreover, the liver Al concentration was found to be lower in the LA and LA+AlCl3 groups compared to the AlCl3 group.

CONCLUSIONS

These results indicate that AlCl3 treatment can induce oxidative stress in the liver. LA supplementation has a beneficial effect on the AlCl3-induced alterations such as high lipid peroxidation, Al accumulation, FA profile ratios and mineral concentrations.

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.

Multifaceted effects of aluminium in neurodegenerative diseases: A review

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

Hesperidin and Silibinin Ameliorate Aluminum-Induced Neurotoxicity: Modulation of Antioxidants and Inflammatory Cytokines Level in Mice Hippocampus

Mounting evidence suggests that long-term aluminum exposure results in severe toxic effects, including neurobehavioral and neurochemical anomalies. The present study was performed to examine the neuroprotective potential of hesperidin and silibinin against aluminum chloride (AlCl3)-induced neurotoxicity in mice. AlCl3 (100 mg/kg/day) was injected daily through oral gavage for 42 days. Concomitantly, hesperidin (50 and 100 mg/kg/day, p.o.) and silibinin (100 and 200 mg/kg/day, p.o.) was administered for 42 days in different groups. The extent of cognitive impairment was assessed by Morris water maze and novel object recognition test on the 43rd day. Neurotoxicity was assessed by measuring oxido-nitrosative stress and proinflammatory cytokines in the hippocampus of mice. Six weeks treatment with AlCl3 caused cognitive impairment as indicated by an increase in the retention latency time and reduction in the percentage of recognition index. AlCl3-treated group showed oxido-nitrosative stress as indicated by increase in the level of lipid peroxidation, nitrite and depleted reduced glutathione, catalase activity in the hippocampus. Moreover, the chronic AlCl3 administration raised the proinflammatory cytokines (interleukin-1β and tumor necrosis factor-α) level and increased acetylcholinesterase activity and reduced the BDNF content in the hippocampus of AlCl3-treated animals. However, chronic treatment with hesperidin and silibinin at higher doses significantly ameliorated the AlCl3-induced cognitive impairment and hippocampal biochemical anomalies. The present study clearly indicated that hesperidin and silibinin exert neuroprotective effects against AlCl3-induced cognitive impairment and neurochemical changes. Amelioration of cognitive impairment may be attributed to the impediment of oxido-nitrosative stress and inflammation in the hippocampus.

The role of serum cholinesterase activity and S100B protein in the evaluation of organophosphate poisoning

The aim of this study was to investigate the role of serum cholinesterase (SChE) activity and S100B protein in the evaluation of patients with acute organophosphate (OP) poisoning. Patients with acute OP poisoning admitted to the emergency department were included in this cross-sectional study. Twenty healthy volunteers served as controls. The SChE activity and serum S100B were determined on admission. Patients were divided into two groups (low severity and high severity). Thirty-six patients diagnosed with acute OP poisoning were enrolled. Serum S100B concentrations were higher in patients than in the control group ( p < 0.05). In the high-severity group, the SChE levels were lower and the S100Bs levels were higher than in the low-severity group. The SChE level was not different between survivors and nonsurvivors. S100B levels were higher in nonsurvivors than in survivors. According to receiver–operating characteristic curve analysis, the optimal cutoff value of serum S100B level to predict mortality was 236.5 pg/mL, with 71.4% sensitivity and 89.7% specificity. Our data suggest that initial SChE level is related to the clinical severity but not with mortality. S100B may be a useful marker in the assessment of clinical severity and prediction of mortality in acute OP poisoning.

Neuroprotective effect of vitamin e supplementation in wistar rat treated with acrylamide

Male wistar rats (weighting 160-180 g) were divided into six groups of six animals per group. Groups A and F served as control. Groups B, C, D, and E received acrylamide at 20 mg/kg body weight for 28 days and groups C and E received additionally vitamin E (50 IU/kg body weight) for 1 to 28 days and 29 to 42 days of experiment, respectively. The animals from groups A, B, and C were sacrificed on day 28 of experiment and from groups D, E, and F on day 42 of experiment, respectively. The FOB (Functional Observational Battery) and histopathological changes were investigated at the end of 4^th week and 6^th week. FOB at the end of 4^th week, of rats given acrylamide alone, or in combination with vitamin E, revealed a significant change in CNS, neuromuscular, and autonomic domains. A marked decrease in grip strength was recorded. A significant increase in foot splay, reduction in width and angle of sequential stride was noticed. Degenerative changes, necrosis, congestion, and kupffer cell proliferation in liver while vacuolar degenerative changes in tubular epithelium, coagulative necrosis, and hemorrhages in kidney were constant findings in acrylamide intoxicated rats. Neuronal degeneration, severe gliosis, congestion were found in brain. Spinal cord revealed demyelination. Acute microscopic softening of lumbar cord, bilateral necrosis with malacia and liquefaction of white matter, and loss of myelin from grey matter were seen. In the recovery period, vitamin E-treated rats revealed improvement in remyelination of spinal cord. In brain mild gliosis was seen. Thus, it appears that vitamin E is not able to protect them from acrylamide toxicity during active feeding, but after cessation of acrylamide feeding treatment with vitamin E revealed faster recovery as compared to the non-treated group.

Aluminium sulphate exposure increases oxidative stress and suppresses brain development in Ross broiler chicks

Background

Aluminium (Al) is known to have neurotoxic effects that can result in oxidative damage to a range of cellular biomolecules. These effects appear to be of significance in the developmental stages of the brain. We therefore investigated the oxidative and histopathological damage induced by Al during growth and development of the chick brain.

Material/Methods

We used a chick embryonic development model, with Al treatment of 500 μg Al sulphate in 0.1 ml saline injected into the egg air chambers at the beginning of their incubation period. The effects on chick-brain growth and development were then assessed at term (day 21). Determination of malondialdehyde and glutathione levels were used as relevant biological measures for increased oxidative stress in terms of lipid peroxidation and biochemical oxidative damage, respectively. Furthermore, we also monitored neuronal degeneration as estimated stereologically using the Cavalieri brain volume estimation tool.

Results

This Al treatment showed significantly increased MDA levels and decreased GSH levels, as indicators of increased biochemical oxidative damage. This was accompanied by significantly decreased brain volume, as a measure of neuronal degeneration during brain development in this chick embryonic development model.

Conclusions

Exposure to Al during chick embryonic development results in increased oxidative stress in the brain that is accompanied by neuronal degeneration.

Vitamin E supplementation decreases muscular and oxidative damage but not inflammatory response induced by eccentric contraction

The purpose of this study was to investigate the effects of vitamin E supplementation on muscular and oxidative damage, as well as the inflammatory response induced by eccentric exercise (EE) in humans. Twenty-one participants with a mean age of 22.5 +/- 4 years, weight of 68.2 +/- 4.9 kg, and height of 173 +/- 4.3 cm were selected and divided randomly into two groups: supplemented (S) (n = 11) and placebo (P) (n = 10). Fourteen days after starting supplementation, subjects performed EE (three sets until exhaustion with elbow flexion and extension on the Scott bench, 80% 1 RM). Blood samples were collected on days 0, 2, 4, and 7 after EE. Muscle soreness (MS), lactate dehydrogenase (LDH) activity, lipid peroxidation, protein carbonylation, tumor necrosis factor-alpha (TNF-alpha), and interleukin 10 (IL-10) levels were determined. We measured a significant increase in MS, LDH, lipid peroxidation, and carbonylation in both groups on days 2, 4, and 7 after eccentric contractions (EC). Values of the supplement group were lower than those of the placebo group at 4 and 7 days after EC in all parameters. Both groups showed significantly increased TNF-alpha on the second day and IL-10 concentration on the fourth and seventh days after EE. The results suggest that vitamin E supplementation represents an important factor in the defense against oxidative stress and muscle damage but not against the inflammatory response in humans.