Aluminum affects glial system and behavior of rats

Post-exposure self-recovery reverses oxidative stress, ameliorates pathology and neurotransmitters imbalance and rescues spatial memory after time-dependent aluminum exposure in rat brain

Aluminum is a potent neurotoxin, responsible for memory impairment and cognitive dysfunction. The neurotoxic effect of aluminum on cognitive impairment is well documented, however, exposure to aluminum in a time-dependent manner and post-exposure self-recovery still needs to be elaborated. This research aimed to (1) study the time-dependent effect of aluminum exposure by administering a total dose of 5850 mg/kg of Al over two different time periods: 30 and 45 days (130 and 195 mg/kg of AlCl3 respectively), and (2) study 20 days post-exposure self-recovery effect in both aluminum-exposed groups by giving distilled water. Cognitive abilities were investigated through Morris water maze test and hole board test and compared in both exposure and recovery groups. Oxidative stress markers and neurotransmitter levels were measured for both exposure and recovery groups. To understand the mechanism of aluminum exposure and recovery, immunohistochemical analysis of synaptophysin (Syp) and glial fibrillary acidic protein (GFAP) was performed. Results showed cognitive dysfunction, oxidative stress-induced damage, reduced neurotransmitter levels, decreased immunoreactivity of Syp, and increased GFAP. However, these parameters showed a larger improvement in the recovery group where rats were given aluminum for 30 days period in comparison to recovery group followed by 45 days of aluminum exposure. These results suggest that restoration of cognitive ability is affected by the duration of aluminum exposure. The study findings provide us with insight into the adverse effects of aluminum exposure and can be utilized to guide future preventive and therapeutic strategies against aluminum neurotoxicity.

Barbaloin's Chemical Intervention in Aluminum Chloride Induced Cognitive Deficits and Changes in Rats through Modulation of Oxidative Stress, Cytokines, and BDNF Expression

Alzheimer's disease (AD) is a long-term neurodegenerative condition characterized by impaired cognitive functions, particularly in the domains of learning and memory. Finding promising options for AD can be successful with a medication repurposing strategy. The goal of the research was to examine the neuroprotective characteristics of barbaloin in aluminum chloride (AlCl3)-induced cognitive deficits and changes in rats through modulation of oxidative stress, cytokines, and brain-derived neurotrophic factor (BDNF) expression. Thirty male Wistar rats were subjected to AlCl3 at a dosage of 100 mg/kg via the per oral route (p.o.), which induced cognitive decline. Morris water maze (MWM) is used to assess behavioral metrics. Assays for catalase (CAT), malondialdehyde (MDA), reduced glutathione (GSH), acetylcholinesterase (AChE), choline-acetyltransferase (ChAT), interleukins-1β (IL-1β), superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α), nuclear factor kappa-B (NF-κB), interleukins-6 (IL-6), BDNF, and neurotransmitter levels [dopamine (DA), acetylcholine (Ach), and γ-aminobutyric acid (GABA)] were performed. Results: The transfer latency time was notably decreased, and substantial modifications in the concentrations of GSH, MDA, CAT, SOD, AChE, ChAT and observed modulations in the formation of interleukins-6 (IL-6), TNF-α, IL-1β, BDNF, and NF-κB were also evidenced after the treatment of rats with barbaloin in comparison to AlCl3-induced control groups. Significant alterations in neurotransmitter levels (DA, Ach, and GABA) were also seen in barbaloin-treated groups in comparison to AlCl3-induced groups. The current investigation has provided evidence that the administration of barbaloin yielded notable enhancements in cognitive function in rats through the inhibition of MDA, enhancing endogenous antioxidant enzymes, reduction of cytokine levels, and enhancement of neurotransmitter contents in the brain. These effects were observed in comparison to a control group treated with AlCl3 and can be attributable to barbaloin's strong anti-inflammatory and antioxidant properties, and metal chelating properties may contribute to its neuroprotective effects. Barbaloin may also promote neuronal survival and enhance learning and memory by upregulating the expression of BDNF.

Amelioration of AlCl3-induced Memory Loss in the Rats by an Aqueous Extract of Guduchi, a Medhya Rasayana

Background

In ayurvedic practice, the Guduchi ( Tinospora cordifolia (Willd.) Miers) stem is used as a Medhya drug for its beneficial effects on memory improvement.

Objectives

The current study was planned to explore the Medhya properties of the Guduchi stem extract by observing its ameliorating effect on AlCl3-induced neurotoxicity in rats that acted as a chronic model of memory loss.

Materials and Methods

The aqueous extract of the Guduchi stem was prepared per the Ayurvedic Pharmacopoeia of India and administered to the AlCl3-treated Wistar rats for 42 days. The biochemical assessment of the brain tissues of the treated animals was done by the acetylcholinesterase (AChE) inhibition assay, protein expression, and oxidative stress assays, namely lipid peroxidation, reduced glutathione, superoxide dismutase, and catalase assay. The neurobehavioral assessment was done using the elevated plus maze (EPM) test.

Results

The EPM test revealed that treatment with Guduchi extract showed marked improvement of memory status in rats along with reduced oxidative stress, and a marked modulation of the AChE inhibition and expression of AChE tubulin proteins.

Conclusion

The results substantiate the Medhya properties of the Guduchi. Detailed investigations are required to be carried out to explore the precise mechanism of the neuroprotective action of the Guduchi stem extract against the AlCl3-induced neurotoxicity in rats.

Naproxen as a potential candidate for promoting rivastigmine anti-Alzheimer activity against aluminum chloride-prompted Alzheimer's-like disease in rats; neurogenesis and apoptosis modulation as a possible underlying mechanism

BACKGROUND AND AIM

Alzheimer's disease (AD) is one of the leading causes of dependence and disability among the elderly worldwide. The traditional anti-Alzheimer medication, rivastigmine, one of the cholinesterase inhibitors (ChEIs), fails to achieve a definitive cure. We tested the hypothesis that naproxen administration to the rivastigmine-treated aluminum chloride (AlCl3) Alzheimer's rat model could provide an additive neuroprotective effect compared to rivastigmine alone.

MATERIALS AND METHODS

The studied groups were control (Cont), AlCl3 treated (Al), rivastigmine treated (RIVA), naproxen treated (Napro), and combined rivastigmine and naproxen treated (RIVA + Napro). Rats' memory, spatial learning, and cognitive behavior were assessed followed by evaluation of hippocampal acetylcholinesterase (AChE) activity. Hippocampal and cerebellar histopathology were thoroughly examined. Activated caspase-3 and the neuroepithelial stem cells marker; nestin expressions were immunohistochemically assayed.

RESULTS

AD rats displayed significantly impaired memory and cognitive function, augmented hippocampal AChE activity; massive neurodegeneration associated with enhanced astrogliosis, apoptosis, and impaired neurogenesis. Except for the enhancement of neurogenesis and suppression of apoptosis, the combination therapy had no additional neuroprotective benefit over rivastigmine-only therapy.

CONCLUSION

Naproxen's efficacy was established by its ability to function at the cellular level, improved neurogenesis, and decreased, apoptosis without having an additional mitigating impact on cognitive impairment in rivastigmine-treated AD rats.

Synergistically enhanced apoptotic and oxidative DNA damaging pathways in the rat brain with lead and/or aluminum metals toxicity: Expression pattern of genes OGG1 and P53

BACKGROUND

Lead (Pb) and aluminum (Al) are ubiquitous environmental pollutants and are known to induce neurodegenerative disorders. They enhance neuronal changes and may involve glial alterations and other consequences. We intend to evaluate the mechanism through which the long-term exposure to Pb acetate alone or in combination with aluminum-chloride induced neurological impacts in rats.

METHODS

For this aim, a total number of forty male Sprague Dawley rats were assigned into four groups. Control (DW), Pb acetate (12.5 mg/kg BW), Al chloride (64 mg/kg BW), and the combination group were experimentally exposed for 60 days. Biochemical evaluation of oxidative stress biomarkers, transcriptional-mediated changes in the expression pattern of OGG1 and P53 genes by qRT-PCR were applied. Histopathological modifications in the brain tissue with immunohistochemical reactivity of GFAP were also detected.

RESULTS

Our findings revealed that lipid peroxidation was markedly enhanced but inhibited antioxidant enzyme activity in brain tissue in all exposed groups regarding the control. Pb-acetate elevated the biochemical concentration of dopamine and serotonin while AlCl₃ declined their levels in the brain homogenate of rats. Furthermore, the exposure to one or both metals elevated the comet assay indices and serum level of 8-hydroxy-2' -deoxyguanosine, up-regulated the expression of P53, OGG1 and GFAP immunoreactivity in the central nervous system. Histologically, they caused several brain tissue alterations.

CONCLUSION

The exposure to Pb and/or Al could be key candidates for neurodegenerative changes in the brain of rats via oxidative, apoptotic, and DNA damaging pathways. Besides, according to our findings, exposure to both Pb acetate and Aluminium chloride have synergistic damaging effects on the central nervous system of rats. Also, they have opposing effects on the secretion of monoamine neurotransmitters DA and 5 H T.

Neurodegenerative and Hepatorenal Disorders Induced Via Aluminum Chloride in Murine System: Impact of β-Secretase, MAPK, and KIM

Aluminum chloride (AlCl₃) is commonly used in daily life; meanwhile, it is the potential etiology of various neurodegenerative as well as hepatorenal diseases. Therefore, the present study was carried out to investigate the correlation between AlCl₃-induced biochemical alterations and the toxicity induced in various organs such as the brain, liver, and kidney. Male mice received AlCl₃ in an oral dose of 50 mg kg^-1 in addition to (50 mg) in drinking water for 2 weeks. Two weeks post-AlCl₃ intoxication, the brain, liver, and kidney biochemical indices were assessed via molecular and western blot analysis. The results are as follows: AlCl₃ intoxication induced a significant elevation in serum malondialdehyde in addition to a significant reduction in serum glutathione (GSH) and superoxide dismutase (SOD) levels. Brain β-secretase (tubulin-binding protein) and tau proteins which are responsible for the synthesis of β-amyloid protein that may interfere with neuronal communication in Alzheimer's disease (AD) were also upregulated; regarding hepatic function, AlCl₃ elevated serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. Moreover, it upregulated hepatic mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) protein expressions as well as renal kidney-inducible molecule-1 (KIM-1) which indicated the deleterious effect of AlCl₃ on these organs. These results were confirmed by histopathological investigations. So, we hypothesize that acute AlCl₃ administration is responsible for oxidative cell damage that interferes with brain function inducing β-amyloid accumulation, Alzheimer's disease, and neurodegenerative damage as well as hepatorenal injuries.

Aluminum exposure promotes histopathological and pro-oxidant damage to the prostate and gonads of male and female adult gerbils

Since the industrial revolution, all living beings have become susceptible to numerous sources of aluminum (Al) exposure. In addition to causing proven toxicity in many organs and systems, Al can also have estrogenic activity when absorbed by the body. The reproductive organs are commonly affected by environmental pollutants with estrogenic activity, but little is known about the effects of Al on the prostate and gonads. Therefore, the aim of this study was to evaluate the effects of subchronic Al exposure on the prostate and gonads of male and female adult gerbils. After 30 days of oral exposure to aluminum chloride (10 mg/kg/day), the animals were euthanized and the organs processed for cytochemical, ultrastructural, and biochemical assays. Ventral male prostates exposed to Al became hyperplastic and showed signs of cell aging. In addition, the male prostate showed decreased catalase (CAT) and superoxide dismutase (SOD) activity. The female prostate was structurally more affected than the ventral male prostate, since it presented hyperplasia and punctual foci of inflammation and prostatic intraepithelial neoplasia. However, CAT and SOD activities did not change in this gland. In the testis, Al promoted immature germ cell detachment and degeneration, as well as reduced CAT activity. In the ovaries, Al caused reduction in folliculogenesis and decreased SOD activity. Together, these results indicate that Al is toxic to the prostate and gonads of adult gerbils and that continuous exposure to this metal can impair the fertility of individuals of both sexes.

Cassia tora extract alleviates Aβ1-42 aggregation processes in vitro and protects against aluminium-induced neurodegeneration in rats

OBJECTIVES

To examine the ability of Cassia tora extract to produce, in vitro and in vivo, beneficial effects with respect to events occurring during Alzheimer's disease.

METHODS

Previously characterised methanol extract of C. tora was tested for its ability to lessen Aβ₄₂ aggregation processes in vitro and to alleviate aluminium-induced impairments in vivo in rats.

KEY FINDINGS

Cassia tora extract prevents the aggregation of monomeric, oligomeric and fibrillary Aβ_1-42 in vitro. Moreover, the daily ingestion of 100 and 400 milligrams of the extract per kilogram of body weight for 60 days ameliorates the neurobehavioral and cognitive abilities of aluminium-treated rats in vivo. Importantly, treatments with the extract trigger a significant recovery of antioxidant enzymes function, a diminution of lipid peroxidation and acetylcholinesterase activity, a decrease of pro-inflammatory cytokines expression and an increase of brain-derived neurotrophic factor levels in both the hippocampus and the frontal cortex. Finally, we evidence that the extract is able to ameliorate the aluminium-dependent loss of neuronal integrity in the CA1 and CA3 regions of the hippocampus.

CONCLUSIONS

Altogether, our results reveal that methanol extract of C. tora is able to prevent typical AD-related events and therefore stands as a promising mild and natural anti-AD multitarget compound.

Aluminium levels in hair and urine are associated with overweight and obesity in a non-occupationally exposed population

BACKGROUND

Data on the association between aluminium (Al) exposure and obesity and/or metabolic syndrome are insufficient. The objective of the present study was to investigate the association between hair and urine Al levels and obesity.

METHODS

A total of 206 lean and 205 obese non-occupationally exposed subjects (30-50 y.o.) were enrolled in the study. Hair and urine Al levels were assessed with ICP-MS. Laboratory quality control was performed using the certified reference materials of human hair, plasma, and urine.

RESULTS

Hair and urinary Al levels in obese subjects were significantly higher by 31% and 46% compared to the control levels, respectively. The presence of hypertension (41% cases), atherosclerosis (8%), type 2 diabetes mellitus (10%), and non-alcoholic fatty liver disease (NAFLD) (53%) in obese patients were not associated with Al levels in the studied subjects. An overall multiple regression model established urinary Al levels (β = 0.395; p < 0.001), hypertension (β = 0.331; p < 0.001) and NAFLD (β = 0.257; p = 0.003) were significantly and directly associated with BMI. Hair Al levels were found to be border-line significantly related to BMI after adjustment for several confounders (β = -0.205; p = 0.054).

CONCLUSIONS

Aluminium body burden is associated with increased body weight, although the causal relationship between Al exposure and obesity is not clear. Both clinical and experimental studies are required to further investigate the impact of Al exposure on metabolic parameters in obesity and especially direct effects of Al in adipose tissue.

Study on the mechanism underlying Al-induced hepatotoxicity based on the identification of the Al-binding proteins in liver

Aluminum (Al) is the most abundant metal element in the earth's crust, and is implicated in the pathogenesis of liver lesions. However, the mechanisms underlying Al³⁺-induced hepatotoxicity are still largely elusive. Based on analysis with native gel electrophoresis, Al³⁺ plus 8-hydroxyquinoline staining and LC-MS/MS, the proteins with high Al³⁺ affinity were identified to be carbamoyl-phosphate synthase, adenosylhomocysteinase, heat shock protein 90-alpha, carbonic anhydrase 3, serum albumin and calreticulin. These proteins are involved in physiological processes such as the urea cycle, redox reactions, apoptosis and so on. Then we established an Al³⁺-treated rat model for biochemical tests, morphology observation and Ca²⁺ homeostasis analysis, in order to evaluate the extent of oxidative damage, hepatic histopathology and specific indicators of Al³⁺-related proteins in liver. Our findings indicated the high-affinity interactions with Al³⁺ perturbed the normal function of the above proteins, which could account for the mechanism underlying Al³⁺-induced hepatotoxicity.

Neuroprotective Effect of Cardamom Oil Against Aluminum Induced Neurotoxicity in Rats

Acetylcholinesterase (AChE) is an enzyme involved in the progression of Alzheimer's disease (AD). Cardamom oil (CO) has been reported to have acetylcholinesterase inhibitory, antioxidant and anti-anxiety effects. Hence, we studied the effect of cardamom oil in aluminum chloride induced neurotoxicity in rats. AD like symptoms were induced in Wistar rats with aluminum chloride (100 mg/kg, p.o.). Cardamom oil was administered concomitantly by oral route at doses of 100 and 200 mg/kg for 42 days. Behavioral parameters like Morris water maze, elevated plus maze, passive avoidance test and locomotor activity were evaluated on day 21 and 42. AChE activity, oxidative stress parameters, histopathological studies and immunohistochemistry studies were carried out in hippocampus and cortex. Cardamom oil treatment showed significant improvement in behavioral parameters, inhibition of AChE activity (p < 0.001) and reduction in oxidative stress in the brain. Histopathological studies of hippocampus and cortex by hematoxylin & eosin (H. & E.) and congo red stain showed inhibition of neuronal damage and amyloid β plaque formation with cardamom oil treatment. Immunohistochemistry showed, CO treatment inhibited amyloid β expression and upregulated brain-derived neurotrophic factor (BDNF). The present study showed that, cardamom oil has neuroprotective effect in aluminum chloride induced neurotoxicity linked with inhibition of AChE activity and reduction in oxidative damage. This effect of cardamom oil may be useful in management of Alzheimer's disease.

EGCG Nanoparticles Attenuate Aluminum Chloride Induced Neurobehavioral Deficits, Beta Amyloid and Tau Pathology in a Rat Model of Alzheimer's Disease

Rational: Alzheimer's disease (AD) is a neurodegenerative pathology characterized by the presence of neuritic plaques and neurofibrillary tangles. Aluminum has been reported to play an important role in the etiology and pathogenesis of this disease. Hence, the present study aimed to evaluate the neuroprotective role of epigallocatechin-gallate (EGCG) loaded nanoparticles (nanoEGCG) against aluminum chloride (AlCl3) induced neurobehavioral and pathological changes in AD induced rats. Method: 100 mg/kg body weight AlCl3 was administered orally for 60 days, which was followed by 10 mg/kg body weight free EGCG and nanoEGCG treatment for 30 days. Morris water maze, open field and novel object recognition tests were employed for neurobehavioral assessment of the rats. This was followed by histopathological assessment of the cortex and the hippocampus in the rat brain. For further validation biochemical, immunohistochemistry and western blot assays were carried out. Result: Aluminum exposure reduced the exploratory and locomotor activities in open field and significantly reduced the memory and learning curve of rats in Morris water maze and novel object recognition tests. These neurobehavioral impairments were significantly attenuated in nanoEGCG treated rats. Histopathological assessment of the cortex and hippocampus of AlCl3 induced rat brains showed the presence of both neuritic plaques and neurofibrillary tangles. In nanoEGCG treated rats this pathology was absent. Significant increase in biochemical, immunohistochemical and protein levels was noted in AlCl3 induced rats. While these levels were greatly reduced in nanoEGCG treated rats. Conclusion: In conclusion, this study strengthens the hypothesis that EGCG nanoparticles can reverse memory loss, neuritic plaque and neurofibrillary tangles formation.

Isorhynchophylline alleviates learning and memory impairments induced by aluminum chloride in mice

BACKGROUND

To evaluate the effect of Isorhynchophylline (IRN) on the learning and memory impairments induced by aluminum chloride (AlCl3) in mice.

METHODS

Fifty male Balb-c mice (4-month-old) were randomly divided into five groups: control, AlCl3 plus vehicle, AlCl3 plus IRN (20 mg/kg), AlCl3 plus IRN (40 mg/kg) and AlCl3 plus donepezil (5 mg/kg). Learning and memory impairments were induced in mice by subcutaneously injecting with AlCl3 (50 mg/kg) once a day for 8 consecutive weeks. At the same time, mice were intragastrically given vehicle or IRN (20 and 40 mg/kg) or donepezil (5 mg/kg) 30 min before each AlCl3 injection. The spatial learning and memory function was assessed using radial arm maze. After sacrificed, the parameters of oxidative stress and cholinergic system in the brain tissues were examined with ELISA kits. Moreover, the expression of nuclear factor kappa B (NF-κB) signaling pathway was analyzed with western blotting.

RESULTS

The results showed that treatment with IRN could significantly ameliorate the cognitive deficits induced by AlCl3 in mice. In addition, treatment with IRN was found to reduce the level of malondialdehyde, enhance the activities of superoxide dismutases and catalase, increase the level of glutathione, and markedly inhibit the activity of acetylcholinesterase (AChE) in the brain tissues of the AlCl3-treated mice. Moreover, IRN significantly suppressed the phosphorylation of NF-κB p65 and IκBα in the brain tissues of AlCl3-treated mice. However, IRN did not show significant effect on the activity of butyrylcholinesterase.

CONCLUSION

Our findings demonstrated for the first time that IRN could alleviate learning and memory impairments induced by AlCl3 in mice. The neuroprotective effect of IRN against AlCl3-induced AD is probably mediated, at least in part, through inhibiting the AChE activity and reducing the oxidative damage of brain tissue via suppress the NF-κB signaling pathway. These results contributed to a better understanding of the in vivo anti-AD mechanism of IRN. It was concluded that IRN could protect the learning and memory function.

How Bad Is Aluminum Exposure to Reproductive Parameters in Rats?

Aluminum (Al) is the most widely distributed metal in the environment and is extensively used in human daily life without any known biological function. It is known that exposure to high concentrations of Al impacts negatively on serum testosterone levels, testicular histomorphometry, and sperm parameters; however, no information is available about the effects of low exposure levels on reproduction. International organizations have established the Al concentration tolerated in drinking water as 3.35 × 10^-4 mg/kg. Therefore, we aimed to compare the effects of long-term exposure to low and high concentrations of Al on male reproductive functions, focusing on testis, epididymis, and sperm parameters. Adult Wistar rats were exposed to aluminum chloride (AlCl₃) at 6.7 × 10^-5, 3.35 × 10^-4, 10, and 40 mg/kg for 112 days by gavage. Al-exposed animals presented low values of testis and epididymis weight, and serum testosterone levels when compared to controls. The stereology of Leydig cells, epididymis histomorphometry, sperm motility, and structural integrity of sperm membranes changed depending on the Al concentration. In regard to epididymis histomorphometry, the initial segment and caput regions were more affected by Al exposure than distal regions. Otherwise, the histology of testis and epididymis did not alter after the Al exposure, as well as sperm morphology. In summary, we concluded that the consequences of Al exposure at low levels were as negative as high levels on reproductive parameters, suggesting adverse impact on male fertility.

Transcriptome-Wide Identification of Differentially Expressed Genes and Long Non-coding RNAs in Aluminum-Treated Rat Hippocampus

Aluminum (Al) is an environmental neurotoxicant with a wide exposure, but the molecular mechanism underlying its toxicity remains unclear. We used RNA sequencing (RNA-seq) in the hippocampus of Al-treated rats to identify 96 upregulated and 652 downregulated mRNAs, and 37 dysregulated long non-coding (lnc)RNAs. Gene ontology analysis showed that dysregulated genes were involved in glial cell differentiation, neural transmission, and vesicle trafficking. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed clustering of differentially expressed mRNAs and lncRNA target genes in several pathways, including the "adenosine monophosphate-activated protein kinase signaling pathway," "extracellular matrix receptor interaction," "the phosphatidylinositol 3 kinase-protein kinase B signaling pathway," and "focal adhesion" signaling pathway. RNA-seq results were validated by reverse transcription (RT)-PCR. Additionally, Al induced changes to the number and morphology of glial cells in the hippocampus of rats, as shown by glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule 1 (Iba1) immunochemistry. RT-PCR and western blotting validated the significant increase in expression of glial cell-related genes GFAP and SOX10 following Al exposure compared with control rats, consistent with RNA-seq results. Collectively, these results suggest that aberrant mRNAs and lncRNAs respond to Al neurotoxicity, and that glial cell-related genes play important roles in the Al neurotoxicity mechanism. These findings provide the basis for designing targeted approaches for the treatment or prevention of Al-induced neurotoxicity.

Behavioral effects of long-term oral administration of aluminum ammonium sulfate in male and female C57BL/6J mice

Background

Aluminum (Al) is considered to be a neurotoxic metal, and excessive exposure to Al has been reported to be a potential risk factor for neurodegenerative diseases. Al ammonium sulfate is one of the Al compounds that is widely used as a food additive. However, the effects of the oral administration of Al ammonium sulfate on physical development and behavior remain to be examined.

Methods

In this study, we investigated the effects of the administration of Al ammonium sulfate 12‐water dissolved in drinking water (0.075 mg/mL) beginning in adolescence on various types of behavior in adult female C57BL/6J mice through a battery of behavioral tests (low‐dose experiment; Experiment 1). We further examined the behavioral effects of the oral administration of a higher dose of the Al compound in drinking water (1 mg/mL) beginning in the prenatal period on behavior in adult male and female mice (high‐dose experiment; Experiment 2).

Results

In the low‐dose experiment, in which females’ oral intake of Al was estimated to be 0.97 mg Al/kg/d as adults, Al‐treated females exhibited an increase in total arm entries in the elevated plus maze test, an initial decrease and subsequent increase in immobility in the forced swim test, and reduced freezing in the fear conditioning test approximately 1 month after the conditioning session compared with vehicle‐treated females (uncorrected P < .05). However, the behavioral differences did not reach a statistically significant level after correction for multiple testing. In the high‐dose experiment, in which animals’ oral intakes were estimated to be about ten times higher than those in the low‐dose experiment, behavioral differences found in the low‐dose experiment were not observed in high‐dose Al‐treated mice, suggesting that the results of the low‐dose experiment might be false positives. Additionally, although high‐dose Al‐treated females exhibited increased social contacts with unfamiliar conspecifics and impaired reference memory performance, and high‐dose Al‐treated mice exhibited decreases in prepulse inhibition and in correct responses in the working memory task (uncorrected P < .05), the differences in any of the behavioral measures did not reach the significance level after correction for multiple testing.

Conclusion

Our results show that long‐term oral exposure to Al ammonium sulfate at the doses used in this study may have the potential to induce some behavioral changes in C57BL/6J mice. However, the behavioral effects of Al were small and statistically weak, as indicated by the fact that the results failed to reach the study‐wide significance level. Thus, further study will be needed to replicate the results and reevaluate the behavioral outcomes of oral intake of Al ammonium sulfate.

Aluminum (Al) ammonium sulfate was orally administered to C57BL/6J mice (estimated dose of 0.97‐9.78 Al mg/kg/d). Behavioral effects of Al were assessed in a battery of behavioral tests in mice in adulthood. Statistically significant behavioral differences were not found between Al‐ and vehicle‐treated mice.

Association between maternal aluminum exposure and the risk of congenital heart defects in offspring

BACKGROUND

Aluminum (Al) is the third most common element in the earth' s crust and has been reported to be teratogenic. However, there is lack of understanding about the association between maternal aluminum exposure and the risks of birth defects such as congenital heart defects (CHDs).

METHODS

A multi-center, hospital-based case-control study was performed at four maternal and child tertiary hospitals in China. A total of 223 cases with CHDs and 223 controls without any abnormalities were recruited according to the inclusion and matching criteria. Hair samples were prepared and measured by inductively coupled plasma mass spectrometry (ICP-MS). The correlation between CHDs and maternal aluminum concentrations was estimated by a 1:1 conditional logistic regression.

RESULTS

The geometric mean and median of hair aluminum levels in isolated or multiple CHD cases was significantly higher than in controls (p < 0.05). A significant association was found between increased hair aluminum concentrations and the risk of total CHDs in offspring (adjusted odds ration [aOR], 2.32; 95% confidence interval [CI], 1.72-3.13), especially in some subtypes of CHDs, such as septal defects (aOR, 2.17; 95% CI, 1.15-4.10), conotruncal defects (aOR, 5.42; 95%CI, 2.43-12.10), and right ventricular outflow track obstruction (aOR, 2.43; 95% CI, 1.08-5.44). However, there was no statistically significant association with left ventricular outflow track obstruction (aOR, 1.66; 95% CI, 0.95-2.88).

CONCLUSION

A high maternal aluminum concentration may significantly increase the risk of delivering a child with a CHD, such as a septal defect, conotruncal heart defect and right-side obstruction.

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

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

Optimal dose of zinc supplementation for preventing aluminum-induced neurotoxicity in rats

Zinc supplementation can help maintain learning and memory function in rodents. In this study, we hypothesized that zinc supplementation could antagonize the neurotoxicity induced by aluminum in rats. Animals were fed a diet containing different doses of zinc (50, 100, 200 mg/kg) for 9 weeks, and orally administered aluminum chloride (300 mg/kg daily) from the third week for 7 consecutive weeks. Open-field behavioral test results showed that the number of rearings in the group given the 100 mg/kg zinc supplement was significantly increased compared with the group given the 50 mg/kg zinc supplement. Malondialdehyde content in the cerebrum was significantly decreased, while dopamine and 5-hydroxytryptamine levels were increased in the groups given the diet supplemented with 100 and 200 mg/kg zinc, compared with the group given the diet supplemented with 50 mg/kg zinc. The acetylcholinesterase activity in the cerebrum was significantly decreased in the group given the 100 mg/kg zinc supplement. Hematoxylin-eosin staining revealed evident pathological damage in the hippocampus of rats in the group given the diet supplemented with 50 mg/kg zinc, but the damage was attenuated in the groups given the diet supplemented with 100 and 200 mg/kg zinc. Our findings suggest that zinc is a potential neuroprotective agent against aluminum-induced neurotoxicity in rats, and the optimal dosages are 100 and 200 mg/kg.

Hemodynamic and neuropathological analysis in rats with aluminum trichloride-induced Alzheimer's disease

BACKGROUND AND AIMS

Hemodynamic normality is crucial to maintaining the integrity of cerebral vessels and, therefore, preserving the cognitive functions of Alzheimer's disease patients. This study investigates the implications of the hemodynamic changes and the neuropathological diversifications of AlCl3-induced AD.

METHODS

The experimental animals were 8- to 12-wk-old male Wistar rats. The rats were randomly divided into 2 groups: a control group and a (+)control group. Food intake, water intake, and weight changes were recorded daily for 22 wk. Synchronously, the regional cerebral blood flow (rCBF) of the rats with AlCl3-induced AD were measured using magnetic resonance imaging (MRI). The hemorheological parameters were analyzed using a computerized auto-rotational rheometer. The brain tissue of the subjects was analyzed using immunohistological chemical (IHC) staining to determine the beta-amyloid (Aβ) levels.

RESULTS

The results of hemodynamic analysis revealed that the whole blood viscosity (WBV), fibrinogen, plasma viscosity and RBC aggregation index (RAI) in (+)control were significantly higher than that of control group, while erythrocyte electrophoresis (EI) of whole blood in (+)control were significantly lower than that of control group. The results of acetylcholinesterase-RBC (AChE-RBC)in the (+)control group was significantly higher than that of the control group. The results also show that the reduction of rCBF in rats with AlCl3-induced AD was approximately 50% to 60% that of normal rats. IHC stain results show that significantly more Aβ plaques accumulated in the hippocampus and cortex of the (+)control than in the control group.

CONCLUSION

The results accentuate the importance of hemorheology and reinforce the specific association between hemodynamic and neuropathological changes in rats with AlCl3-induced AD. Hemorheological parameters, such as WBV and fibrinogen, and AChE-RBC were ultimately proven to be useful biomarkers of the severity and progression of AD patients. In addition, the parameters can be substituted for invasive inspection in therapeutic intervention.

Accelerated tau aggregation, apoptosis and neurological dysfunction caused by chronic oral administration of aluminum in a mouse model of tauopathies

To clarify whether long-term oral ingestion of aluminum (Al) can increase tau aggregation in mammals, we examined the effects of oral Al administration on tau accumulation, apoptosis in the central nervous system (CNS) and motor function using tau transgenic (Tg) mice that show very slowly progressive tau accumulation. Al-treated tau Tg mice had almost twice as many tau-positive inclusions in the spinal cord as tau Tg mice without Al treatment at 12 months of age, a difference that reached statistical significance, and the development of pretangle-like tau aggregates in the brain was also significantly advanced from 9 months. Al exposure did not induce any tau pathology in wild-type (WT) mice. Apoptosis was observed in the hippocampus in Al-treated tau Tg mice, but was virtually absent in the other experimental groups. Motor function as assessed by the tail suspension test was most severely impaired in Al-treated tau Tg mice. Given our results, chronic oral ingestion of Al may more strongly promote tau aggregation, apoptosis and neurological dysfunction if individuals already had a pathological process causing tau aggregation. These findings may also implicate chronic Al neurotoxicity in humans, who frequently have had mild tau pathology from a young age.

Hippocampal neuronal loss, decreased GFAP immunoreactivity and cognitive impairment following experimental intoxication of rats with aluminum citrate

Aluminum (Al) is a neurotoxic agent with deleterious actions on cognitive processes. Nevertheless, few studies have investigated the neuropathological effects underlying the Al-induced cognitive impairment. We have explored the effects of acute Al citrate intoxication on both hippocampal morphology and mnemonic processes in rodents. Adult male Wistar rats were intoxicated with a daily dose of Al citrate (320 mg/kg) during 4 days by gavage. Animals were perfused at 8 (G2), 17 (G3) and 31 days (G4) after intoxication. Control animals were treated with sodium citrate (G1). Animals were submitted to behavioral tests of open field and elevated T-maze. Immunohistochemistry was performed to label neurons (anti-NeuN) and astrocytes (anti-GFAP) in both CA1 and CA3 hippocampal regions. There was an increase in the locomotor activity in open field test for G2 in comparison to control group and other groups (ANOVA-Bonferroni, P<0.05). The elevated T-maze avoidance latency (AL) was higher in all intoxicated groups compared to control (P<0.05) in avoidance 1. These values remained elevated in avoidance 2 (P<0.05), but abruptly decreased in G2 and G3, but not in G1 and G4 animals in avoidance 3 (P<0.05). There were no significant differences for 1 and 2 escape latencies. There were intense neuronal loss and a progressive decrease in GFAP immunoreactivity in the hippocampus of intoxicated animals. The results suggest that Al citrate treatment induces deficits on learning and memory concomitant with neuronal loss and astrocyte impairment in the hippocampus of intoxicated rats.

The effect of minocycline on the masticatory movements following the inferior alveolar nerve transection in freely moving rats

Background

To determine the effects of inferior alveolar nerve transection (IAN-X) on masticatory movements in freely moving rats and to test if microglial cells in the trigeminal principal sensory nucleus (prV) or motor nucleus (motV) may be involved in modulation of mastication, the effects of microglial cell inhibitor minocycline (MC) on masticatory jaw movements, microglia (Iba1) immunohistochemistry and the masticatory jaw movements and related masticatory muscle EMG activities were studied in IAN-X rats.

Results

The number of Iba1-immunoreactive (IR) cells both in prV and motV was significantly larger in IAN-X rats compared with sham rats on day 3 after IAN-X. The intraperitoneal (i.p.) administration of MC caused a significant reduction of the number of Iba1-IR cells both in prV and motV that was evident on day 14 after IAN-X. Furthermore, a significant reduction of the number of Iba1-IR cells could be observed in motV but not in prV after microinjection (m.i.) of MC into the motV of IAN-X rats. The rats also exhibited a significant decrease in the head-withdrawal threshold on the side ipsilateral to the IAN-X compared to the threshold before IAN-X and it lasted to day 14. In addition, IAN-X markedly affected the ability to rat to carry out mastication. The number of complete masticatory sequences was significantly decreased. Furthermore, the total masticatory sequence time and food preparatory (PP) period duration was significantly elongated in compared to sham rats. Although IAN-X significantly affected the total number of chewing cycles within the RC period of a masticatory sequence, it had no effect on the duration of the chewing cycles. On the other hand, systemic administration of MC (both i.p. and m.i.) in IAN-X rats significantly improved decreased head-withdrawal threshold and the impaired masticatory jaw movements.

Conclusions

The present findings reveal that the strong modulation of masticatory jaw movements occurs following microglial cell activation after IAN-X, and the modulation recovers after inhibition of the microglial cell activation by MC, suggesting that microglial cell activation in the motV as well as in the prV has a pivotal role in modulating mastication following trigeminal nerve injury associated with orofacial neuropathic pain.

Lethality, accumulation and toxicokinetics of aluminum in some tissues of male albino rats

In the present work, the lethality percentiles including median lethal doses (LD50), accumulation, distribution and toxicokinetics of aluminum in the liver, kidney, intestine, brain and serum of male albino rats, following a single oral administration were studied throughout 1, 3, 7, 14 and 28 days. The estimated LD50 at 24 h was 3.45 g Al/kg body weight (b.wt.). The utilized dose of Al was 1/50 LD50 (0.07 g Al/kg b.wt.). Aluminum residues, in Al-treated rats, were significantly decreased in response to the experimental periods and were negatively correlated with time. In addition, the hepatic, renal, intestinal, brain and serum Al contents were significantly higher than the corresponding controls at all experimental periods, except the brain that showed significant depletion when compared with its corresponding control after 28 days. Kinetically, the highest average of Al area under concentration − time curves (AUCtotal, μg/g day) and area under moment concentration − time curves (AUMCtotal, µg/g day2) recorded in the brain followed by kidney, serum, intestine and liver. The longest elimination half-life time ( t1/2, day) and the mean residence time (MRT, day) were recorded in the brain followed by the liver, kidney, serum and intestine. On the other hand, the slowest clearance rates (Cls, L/day) of Al, in order, were recorded in brain, kidney, serum, intestine and the liver. The elimination rate constant ( Lz, day−1) of Al from the brain was less than that in the intestine and serum was less than that in the liver and kidney. The computed maximum concentrations ( Cmax) of Al in the intestine > kidney > serum > brain > liver were recorded after 3, 3.8, 2.2, 5.4 and 3.8 days, respectively. The computed starting concentration ( C0, μg) of Al in serum was higher than its level in the intestine followed by the brain, kidney and liver.

Effects of chronic lead intoxication on rat serotoninergic system and anxiety behavior

Chronic lead exposure has been shown to produce behavioral disturbances in human and animal models. These disturbances are associated with alterations in monoaminergic neurotransmission in the central nervous system (CNS), some of which have been attributed to serotonin (5-HT). This study was undertaken to investigate the chronic effects of lead exposure on the serotoninergic system in the dorsal raphe nucleus (DRN) and the consequences of its toxicity on rat behavior. Adult male Wistar rats were chronically exposed for 3 months to 0.5% lead acetate in drinking water. The serotoninergic system was evaluated using immunohistochemistry and the anxiety behavior was assessed by the light/dark box test. The results show that chronic lead exposure induces a significant increase of blood and brain lead levels in treated rats compared with controls. The density of the immunoreactive serotoninergic cell bodies was significantly higher in treated rats in all parts of the DRN. Assessment of animal behavior using the light/dark box test showed that lead-treated rats spent significantly more time in the light chamber compared with controls (P=0.001). These findings suggest that lead exposure may possibly induce increased anxiety as a consequence of changes in neuronal 5-HT content in the DRN.

Chronic lead intoxication affects glial and neural systems and induces hypoactivity in adult rat

Lead is an environmental toxin and its effects are principally manifested in the brain. Glial and neuronal changes have been described during development following chronic or acute lead intoxication, however, little is known about the effects of chronic lead intoxication in adults. In this study we evaluated immunohistochemically the glial and dopaminergic systems in adult male Wistar rats. 0.5% (v/v) lead acetate in drinking water was administrated chronically over a 3-month period. Hypertrophic immunoreactive astrocytes were observed in the frontal cortex and other brain structures of the treated animals. Analysis of the astroglial features showed increased number of astrocyte cell bodies and processes in treated rats, an increase confirmed by Western blot. Particular distribution of glial fibrillary acidic protein immunoreactivity was observed within the blood vessel walls in which dense immunoreactive glial processes emanate from astrocytes. Glial changes in the frontal cortex were concomitant with reduced tyrosine hydroxylase immunoreactive neuronal processes, which seem to occur as a consequence of significantly reduced dopaminergic neurons within the nucleus of origin in the substantia nigra. These glial and neuronal changes following lead intoxication may affect animal behavior as evidenced by reduced locomotor activity in an open field test. These findings demonstrate that chronic lead exposure induces astroglial changes, which may compromise neuronal function and consequently animal behavior.

Rivastigmine reverses aluminum-induced behavioral changes in rats

Aluminum, a known neurotoxin, has long been implicated in the pathogenesis of Alzheimer's disease. Its exposure is associated with impairment in the cholinergic system in the brain. In this study we investigated the behavioral effects of aluminum in rats and the possible effect of rivastigmine, a cholinesterase inhibitor, on the aluminum-induced behavioral changes. Rats were exposed to aluminum chloride (100 mg/kg/day i.p.) for 60 days before the start of behavioral tests. Rivastigmine was given in doses of 0.5, 1, 1.5 and 2.5 mg/kg i.p. 60 min before the behavioral tests. Five tests were investigated; open field test, Morris water maze, radial arm maze, passive avoidance test and rota-rod test. Results showed that aluminum exposure was associated with significant reductions in spontaneous locomotor and exploratory activities in open field test and significant impairments in learning and memory in Morris water maze, radial arm maze and passive avoidance tests. The behavioral impairments caused by aluminum were significantly improved by rivastigmine. Neither aluminum alone nor co-treatment with rivastigmine caused any significant alteration of the animals' performance in rota-rod test. The improvements in activity, learning and memory caused by rivastigmine were found to be dose-dependent, and the maximal improvement was encountered with its large dose (2.5 mg/kg). From these results we can conclude that rivastigmine can reverse behavioral deficits caused by aluminum intoxication.

Chronic exposure to aluminum reduces tyrosine hydroxylase expression in the substantia nigra and locomotor performance in rats

Aluminum (Al) is a neurotoxic agent that accumulates in the substantia nigra of patients affected by Parkinson's disease and in other cerebral areas of different neurodegenerative pathologies. Al has been associated with neuronal and glial dysfunctions, and neuronal changes have been suggested to affect several neurotransmitter systems including the dopaminergic system. The present study was designed to evaluate by means of immunohistochemistry using antibodies against tyrosine hydroxylase (TH; the rate-limiting enzyme of dopamine synthesis) the effects of chronic Al exposure (0, 3%) in drinking water during 4 months in adulthood or since intra-uterine age in the substantia nigra. Our results show a significant decrease in the number of cells labeled by the antibody against TH in rats treated with Al compared to controls. The TH-immunoreactive decrease following Al treatment is accentuated in the rat group treated since intrauterine age. In both treated groups, Al exposure induced a significant decrease of locomotor performance. Interestingly, as for TH-immunoreactivity, the decreased locomotor activity was also accentuated in the group treated since intrauterine age. The Al-induced TH alterations may be one of the causes of aluminum-induced neurotoxicity.