Vanadium (V)-Induced Neurotoxicity in the Rat Central Nervous System: A Histo-Immunohistochemical Study

Histological and Memory Alterations in an Innovative Alzheimer's Disease Animal Model by Vanadium Pentoxide Inhalation

Background

Previous work from our group has shown that chronic exposure to Vanadium pentoxide (V2O5) causes cytoskeletal alterations suggesting that V2O5 can interact with cytoskeletal proteins through polymerization and tyrosine phosphatases inhibition, causing Alzheimer's disease (AD)-like hippocampal cell death.

Objective

This work aims to characterize an innovative AD experimental model through chronic V2O5 inhalation, analyzing the spatial memory alterations and the presence of neurofibrillary tangles (NFTs), amyloid-β (Aβ) senile plaques, cerebral amyloid angiopathy, and dendritic spine loss in AD-related brain structures.

Methods

20 male Wistar rats were divided into control (deionized water) and experimental (0.02 M V2O5 1 h, 3/week for 6 months) groups (n = 10). The T-maze test was used to assess spatial memory once a month. After 6 months, histological alterations of the frontal and entorhinal cortices, CA1, subiculum, and amygdala were analyzed by performing Congo red, Bielschowsky, and Golgi impregnation.

Results

Cognitive results in the T-maze showed memory impairment from the third month of V2O5 inhalation. We also noted NFTs, Aβ plaque accumulation in the vascular endothelium and pyramidal neurons, dendritic spine, and neuronal loss in all the analyzed structures, CA1 being the most affected.

Conclusions

This model characterizes neurodegenerative changes specific to AD. Our model is compatible with Braak AD stage IV, which represents a moment where it is feasible to propose therapies that have a positive impact on stopping neuronal damage.

Attenuation of Vanadium-Induced Neurotoxicity in Rat Hippocampal Slices (In Vitro) and Mice (In Vivo) by ZA-II-05, a Novel NMDA-Receptor Antagonist

Exposure to heavy metals, such as vanadium, poses an ongoing environmental and health threat, heightening the risk of neurodegenerative disorders. While several compounds have shown promise in mitigating vanadium toxicity, their efficacy is limited. Effective strategies involve targeting specific subunits of the NMDA receptor, a glutamate receptor linked to neurodegenerative conditions. The potential neuroprotective effects of ZA-II-05, an NMDA receptor antagonist, against vanadium-induced neurotoxicity were explored in this study. Organotypic rat hippocampal slices, and live mice, were used as models to comprehensively evaluate the compound's impact. Targeted in vivo fluorescence analyses of the hippocampal slices using propidium iodide as a marker for cell death was utilized. The in vivo study involved five dams, each with eight pups, which were randomly assigned to five experimental groups (n = 8 pups). After administering treatments intraperitoneally over six months, various brain regions were assessed for neuropathologies using different immunohistochemical markers. High fluorescence intensity was observed in the hippocampal slices treated with vanadium, signifying cell death. Vanadium-exposed mice exhibited demyelination, microgliosis, and neuronal cell loss. Significantly, treatment with ZA-II-05 resulted in reduced cellular death in the rat hippocampal slices and preserved cellular integrity and morphological architecture in different anatomical regions, suggesting its potential in countering vanadium-induced neurotoxicity.

Impact of Environmental Risk Factors on Mitochondrial Dysfunction, Neuroinflammation, Protein Misfolding, and Oxidative Stress in the Etiopathogenesis of Parkinson's Disease

As a prevalent progressive neurodegenerative disorder, Parkinson's disease (PD) is characterized by the neuropathological hallmark of the loss of nigrostriatal dopaminergic (DAergic) innervation and the appearance of Lewy bodies with aggregated α-synuclein. Although several familial forms of PD have been reported to be associated with several gene variants, most cases in nature are sporadic, triggered by a complex interplay of genetic and environmental risk factors. Numerous epidemiological studies during the past two decades have shown positive associations between PD and several environmental factors, including exposure to neurotoxic pesticides/herbicides and heavy metals as well as traumatic brain injury. Other environmental factors that have been implicated as potential risk factors for PD include industrial chemicals, wood pulp mills, farming, well-water consumption, and rural residence. In this review, we summarize the environmental toxicology of PD with the focus on the elaboration of chemical toxicity and the underlying pathogenic mechanisms associated with exposure to several neurotoxic chemicals, specifically 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), rotenone, paraquat (PQ), dichloro-diphenyl-trichloroethane (DDT), dieldrin, manganese (Mn), and vanadium (V). Our overview of the current findings from cellular, animal, and human studies of PD provides information for possible intervention strategies aimed at halting the initiation and exacerbation of environmentally linked PD.

Neuroecotoxicology: Effects of environmental heavy metal exposure on the brain of African giant rats and the contribution of vanadium to the neuropathology

Increased exploitation of minerals has led to pollution of confined environments as documented in Nigeria Niger Delta. Information on the effects on brain of such exposure is limited. Due to its exploratory activities, the African giant rat (Cricetomys gambianus) (AGR) provides a unique model for neuroecotoxicological research to determine levels of animal and human exposure to different pollutants. This study aims to unravel neuropathological features of AGR sampled from three agro-ecological zones of Nigeria. Fifteen AGR were sampled according to previously determined data on heavy metal exposure: high vanadium, high lead, and low metals. Eighteen AGR were collected from low metal zone and divided into two groups. Control group received vehicle while SMV exposed group received 3 mg/kg sodium metavanadate (SMV) intraperitoneally for 14days. Brain immunohistochemical analyses were conducted, and ultrastructural changes were studied in experimentally exposed group. Results showed significant loss of tyrosin hydroxylase, parvalbumin, orexin-A and melanin concentration hormone containing neuronal populations in brains obtained from high vanadium and high lead zones and in experimentally intoxicated SMV groups. Similarly, significant decrease numbers of dendritic arborations; extracellular matrix density, perineuronal nets; astrocytes and microglia activations are documented in same groups. Ultrastructural studies revealed mass denudation, cilia loss, disintegration of ependymal layer and intense destructions of myelin sheaths in SMV exposed group. These are the first "neuroecotoxicological" findings in distinct neuronal cells. The implications of these findings are highly relevant for human population living in these areas, not only in Nigeria but also in similarly polluted areas elsewhere in the world.

Effects of Quercetin and Resveratrol on Zinc Chloride- and Sodium Metavanadate-Induced Passive Avoidance Memory Retention Deficits in Male Mice

Quercetin and resveratrol are found in a variety of fruits and vegetables and have several biological and pharmacological properties. In this study, the effects of quercetin [50 mg/kg, intraperitoneal (i.p.)] and resveratrol (50 mg/kg, i.p.) on zinc chloride (ZnCl₂; 75 mg/kg/d, 2 weeks oral gavage) and sodium metavanadate (SMV; 22.5 mg/kg/d, 2 weeks oral gavage) induced passive avoidance memory retention were investigated in step-through passive avoidance tasks. ZnCl₂ was dissolved in saline and SMV was dissolved in drinking water. Mice received ZnCl₂ or SMV orally for two weeks and were administered quercetin or resveratrol by i.p. injection on day 14, days 12 and 14, or days 10, 12, and 14. At the end of treatment, animals were trained for one day in a step-through passive avoidance task, then alterations in avoidance memory retention were evaluated after 24, 48, 96, and 168 h. Oral consumption of ZnCl₂ and SMV decreased latency time compared with control groups. Both quercetin and resveratrol (50 mg/kg, i.p.) prevented ZnCl₂- and SMV-induced avoidance memory retention impairments and did not significantly alter muscle strength, as demonstrated in rotarod tasks. No significant differences were observed between mice who received single, double, or triple doses of quercetin or resveratrol. The results suggest that quercetin and resveratrol may have preventive effects on ZnCl₂- and SMV-induced memory impairment in male mice.

The ameliorative effects of a phenolic derivative of Moringa oleifera leave against vanadium-induced neurotoxicity in mice

Vanadium, a transition series metal released during some industrial activities, induces oxidative stress and lipid peroxidation. Ameliorative effect of a pure compound from the methanolic extract of Moringa oleifera leaves, code-named MIMO2, in 14-day old mice administered with vanadium (as sodium metavanadate 3 mg/kg) for 2 weeks was assessed. Results from body weight monitoring, muscular strength, and open field showed slight reduction in body weight and locomotion deficit in vanadium-exposed mice, ameliorated with MIMO2 co-administration. Degeneration of the Purkinje cell layer and neuronal death in the hippocampal CA1 region were observed in vanadium-exposed mice and both appeared significantly reduced with MIMO2 co-administration. Demyelination involving the midline of the corpus callosum, somatosensory and retrosplenial cortices was also reduced with MIMO2. Microglia activation and astrogliosis observed through immunohistochemistry were also alleviated. Immunohistochemistry for myelin, axons and oligodendrocyte lineage cells were also carried out and showed that in vanadium-treated mice brains, oligodendrocyte progenitor cells increased NG2 immunolabelling with hypertrophy and bushy, ramified appearance of their processes. MIMO2 displayed ameliorative and antioxidative effects in vanadium-induced neurotoxicity in experimental murine species. This is likely the first time MIMO2 is being used in vivo in an animal model.

Ficus exasperata Vahl leaves extract attenuates motor deficit in vanadium-induced parkinsonism mice

Medicinal herbs have played significant roles in the treatment of various diseases in humans and animals. Sodium metavanadate is a potentially toxic environmental pollutant that induces oxidative damage, neurological disorder, Parkinsonism and Parkinson-like disease upon excessive exposure. This study is designed to investigate the impact of saponin fraction of Ficus exasperata Vahl leaf extract (at 50 and 100 mg/kg body weight for 14 days at different animal groupings) on vanadium treated mice. Animals were randomly grouped into five groups. Control (normal saline), NaVO₃ (10 mg/kg for 7 days), withdrawal group, NaVO₃+Vahl (low dose) and NaVO₃+Vahl (high dose). The animals were screened for motor coordination using rotarod and PBTs and a post mortem study was conducted by quantitatively assessing the markers of oxidative stress such as lipid peroxidation, catalase, glutathione activities, and also through immunohistochemistry via glia fibrillary acidic protein, tyrosine hydroxylase and dopamine transporter to study the integrity of astrocytes and dopaminergic neurons of the substantia nigra (SNc). Vanadium-exposed group showed a decreased motor activity on the neurobehavioural tests as well as an increase in markers of oxidative stress. Saponin fraction of F. exasperata Vahl leaves extract produced a statistically significant motor improvement which may be due to high antioxidant activities of saponin, thereby providing an ameliorative effect on the histoarchitecture of the SNc. It can be inferred that the saponin fraction of F. exasperata Vahl leaves extract to possesses ameliorative, motor-enhancing and neurorestorative benefit on motor deficit in vanadium-induced parkinsonism mice.

Novel NMDA-receptor antagonists ameliorate vanadium neurotoxicity

Various NMDA-receptor antagonists have been investigated for their therapeutic potential in Alzheimer's disease with memantine shown to be safe and with relative efficacy. There is, however, need to develop novel drugs to counter tolerance and with better efficacy in ameliorating neurodegeneration. We have shown neurodegeneration in different models of vanadium-exposed mice. This study was designed to evaluate and ascertain the potency of three novel NMDA-receptor antagonists (Compounds A, B and C) to ameliorate neurodegeneration in vanadium-exposed mice. One-month-old mice (n = 6) received sterile water (control) and another group (n = 6) was treated with vanadium (3 mg/kg sodium metavanadate) intraperitoneally for 1 month. Three other groups (n = 6) received vanadium and compounds A, B and C (4.35 mg/kg, 30 mg/kg and 100 mg/kg, respectively) simultaneously for the same period. Assessment of pathologies and neurodegeneration in different brain regions was done to test the ameliorative effects of the 3 antagonists using different immunohistochemical markers. Vanadium exposure resulted in reduced calbindin expression and pyknosis of Purkinje cells, cell loss and destruction of apical dendrites with greater percentage of cytoplasmic vacuolations, morphological alterations characterized by cell clustering and multiple layering patterns in the Purkinje cell layer. In addition, the observed degeneration included demyelination, increased GFAP-immunoreactive cells and microgliosis. Simultaneous administration of the compounds to vanadium-exposed mice resulted in the preservation of cellular integrity in the same anatomical regions and restoration of the cells' vitality with reduced astroglial and microglial activation.

Mini review-vanadium-induced neurotoxicity and possible targets

Vanadium, a transition metal, ubiquitous in nature is known to have therapeutic effect as well as toxic effect. It is known to possess antidiabetic, antitumor and antiparasitic activity. However, on long term exposure, it produces neurotoxicity which may result in memory impairment. The possible mechanism known to cause neurotoxicity suggested is oxidative stress and inflammation of neuronal cells. The present review has focused on discussing the role of protein P38 mitogen-activated protein kinase and oxidative stress as possible targets to treat vanadium-induced neurotoxicity.

Neuroprotective effect of carnosine in the olfactory bulb after vanadium inhalation in a mouse model

Carnosine (β-alanyl-L-histidine) is synthesized in the olfactory system, has antioxidant activity as a scavenger of free radicals and has been reported to have neuroprotective action in diseases which have been attributed to oxidative damage. In neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases, impairment of olfactory function has been described. Vanadium derivatives are environmental pollutants, and its toxicity has been associated with oxidative stress. Vanadium toxicity on the olfactory bulb was reported previously. This study investigates the neuroprotective effect of carnosine on the olfactory bulb in a mice model of vanadium inhalation. Male mice were divided into four groups: vanadium pentoxide (V2 O5 ) [0.02 mol/L] inhalation for one hour twice a week; V2 O5 inhalation plus 1 mg/kg of carnosine administered daily; carnosine only, and the control group that inhaled saline. The olfactory function was evaluated using the odorant test. Animals were sacrificed four weeks after exposure. The olfactory bulbs were dissected and processed using the rapid Golgi method; cytological and ultrastructural analysis was performed and malondialdehyde (MDA) concentrations were measured. The results showed evidence of olfactory dysfunction caused by vanadium exposure and also an increase in MDA levels, loss of dendritic spines and necrotic neuronal death in the granule cells. But, in contrast, vanadium-exposed mice treated with carnosine showed an increase in dendritic spines and a decrease in neuronal death and in MDA levels when compared with the group exposed to vanadium without carnosine. These results suggest that dendritic spine loss and ultrastructural alterations in the granule cells induced by vanadium are mediated by oxidative stress and that carnosine may modulate the neurotoxic vanadium action, improving the olfactory function.

Sodium metavanadate induced cognitive decline, behavioral impairments, oxidative stress and down regulation of myelin basic protein in mice hippocampus: Ameliorative roles of β-spinasterol, and stigmasterol

INTRODUCTION

Exposures to toxic levels of vanadium and soluble vanadium compounds cause behavioral impairments and neurodegeneration via free radical production. Consequently, natural antioxidant sources have been explored for effective and cheap remedy following toxicity. Grewia carpinifolia has been shown to improve behavioral impairments in vanadium-induced neurotoxicity, however, the active compounds implicated remains unknown. Therefore, this study was conducted to investigate ameliorative effects of bioactive compounds from G. carpinifolia on memory and behavioral impairments in vanadium-induced neurotoxicity.

METHODS

Sixty BALB/c mice were equally divided into five groups (A-E). A (control); administered distilled water, B (standard); administered α-tocopherol (500 mg/kg) every 72 hr orally with daily dose of sodium metavanadate (3 mg/kg) intraperitoneally, test groups C, and D; received single oral dose of 100 μg β-spinasterol or stigmasterol (bioactive compounds from G. carpinifolia), respectively, along with sodium metavanadate and the model group E, received sodium metavanadate only for seven consecutive days. Memory, locomotion and muscular strength were accessed using Morris water maze, Open field and hanging wire tests. In vivo antioxidant and neuroprotective activities were evaluated by measuring catalase, superoxide dismutase, MDA, H₂ O₂ , and myelin basic protein (MBP) expression in the hippocampus.

RESULTS

In Morris water maze, stigmasterol significantly (p ≤ 0.05) decreased escape latency and increased swimming time in target quadrant (28.01 ± 0.02; 98.24 ± 17.38 s), respectively, better than α-tocopherol (52.43 ± 13.25; 80.32 ± 15.21) and β-spinasterol (42.09 ± 14.27; 70.91 ± 19.24) in sodium metavanadate-induced memory loss (112.31 ± 9.35; 42.35 ± 11.05). β-Spinasterol and stigmasterol significantly increased exploration and latency in open field and hanging wire tests respectively. Stigmasterol also increased activities of antioxidant enzymes, decreased oxidative stress markers and lipid peroxidation in mice hippocampal homogenates, and increased MBP expression.

CONCLUSIONS

The findings of this study indicate a potential for stigmasterol, a bioactive compound from G. carpinifolia in improving cognitive decline, motor coordination, and ameliorating oxidative stress in vanadium-induced neurotoxicity.

Changes in the brain antioxidant profile after chronic vanadium administration in mice

Vanadium is known to induce reactive oxygen species (ROS) in biological systems. Exposure to vanadium has been linked to neurological defects affecting the central nervous system (CNS) early in life and culminates later to neurodegeneration. This study was designed to evaluate the effects of chronic vanadium exposure on antioxidant profile in mice, and progressive changes after withdrawal from treatment. A total of 85 male BALB/c mice (4 weeks old) were used for the experiment and were divided into three groups of vanadium exposed (3 mg/kg i.p at 3-18 months treatment), matched controls, and animals exposed to vanadium for three months and thereafter vanadium was withdrawn. Vanadium exposure caused significant increases (p<0.05) in levels of malondialdehyde (MDA), hydrogen peroxide (H₂O₂) generation and nitric oxide with a concomitant decrease (p<0.05) in the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione-S-transferase and a decline in the level of reduced glutathione (GSH) after 6 months of vanadium exposure in the brain. This trend continued in all vanadium-exposed groups (9, 12, 15 and 18 months) relative to the matched controls. Withdrawal after 3 months of vanadium exposure significantly reversed oxidative stress in intoxicated mice from 9 to 15 months after vanadium withdrawal. We have shown that chronic administration of vanadium led to oxidative stress in the brain which is reversible only after a long period of vanadium withdrawal.

Cellular responses of human astrocytoma cells to dust from the Acheson process: An in vitro study

Silicon carbide (SiC) is largely used in various products such as diesel particulate filters and solar panels. It is produced through the Acheson process where aerosolized fractions of SiC and other by-products are generated in the work environment and may potentially affect the workers' health. In this study, dust was collected directly on a filter in a furnace hall over a time period of 24h. The collected dust was characterized by scanning electron microscopy and found to contain a high content of graphite particles, and carbon and silicon containing particles. Only 6% was classified as SiC, whereof only 10% had a fibrous structure. To study effects of exposure beyond the respiratory system, neurotoxic effects on human astrocytic cells, were investigated. Both low, occupationally relevant, and high doses from 9E-6μg/cm² up to 4.5μg/cm² were used, respectively. Cytotoxicity assay indicated no effects of low doses but an effect of the higher doses after 24h. Furthermore, investigation of intracellular reactive oxygen species (ROS) indicated no effects with low doses, whereas a higher dose of 0.9μg/cm² induced a significant increase in ROS and DNA damage. In summary, low doses of dust from the Acheson process may exert no or little toxic effects, at least experimentally in the laboratory on human astrocytes. However, higher doses have implications and are likely a result of the complex composition of the dust.

Isolation of a novel compound (MIMO2) from the methanolic extract of Moringa oleifera leaves: protective effects against vanadium-induced cytotoxity

Moringa oleifera is reported to be a miracle plant, with positive effects on practically every system in the animal body. The methanolic extract of Moringa oleifera leaves was fractionated using liquid-liquid fractionation, column chromatography and preparative high-performance liquid chromatography (HPLC). Bioassay guided fractionation using Ferric Reducing Antioxidant Power (FRAP) was used to determine the fraction with the highest antioxidative power. Chemical structure was elucidated with nuclear magnetic resonance (NMR) spectroscopy. FRAP showed that the pure compound, butyl p-hydroxyphenyl-acetate (MIMO2) exhibited an antioxidant activity higher than TEMPOL (positive control). Vanadium is a metal, which as a salt has been shown to be a neurotoxicant; and was therefore used to assess the efficacy of MIMO2 in this experiment. HT22 (immortalized mouse hippocampal) cells were used for cell culture. The Comet assay showed a statistically significant reduction (p < .05) in DNA damage when 0.25 and 0.5 μM MIMO2 as well as 0.1 and 0.2 mg of the methanolic extract of Moringa oleifera leaves (MO) were used in combination with 200 μM vanadium (sodium metavanadate). Analogously, a reduced formation of superoxide was observed using dihydroethidium (2,7-Diamino-10-ethyl-9-phenyl-9,10-dihydrophenanthridine-DHE) stain after 0.5 μM MIMO2 and 0.063 mg MO were used in combination with vanadium 100 μM. MIMO2 and MO gave a statistically significant (p < .05) protective effect against vanadium toxicity on neuronal cells. Further assays may need to be performed to assess the extent of protection that MIMO2 may offer, and also to better understand its mechanisms of action.

Brain Metal Distribution and Neuro-Inflammatory Profiles after Chronic Vanadium Administration and Withdrawal in Mice

Vanadium is a potentially toxic environmental pollutant and induces oxidative damage in biological systems including the central nervous system (CNS). Its deposition in brain tissue may be involved in the pathogenesis of certain neurological disorders which after prolonged exposure can culminate into more severe pathology. Most studies on vanadium neurotoxicity have been done after acute exposure but in reality some populations are exposed for a lifetime. This work was designed to ascertain neurodegenerative consequences of chronic vanadium administration and to investigate the progressive changes in the brain after withdrawal from vanadium treatment. A total of 85 male BALB/c mice were used for the experiment and divided into three major groups of vanadium treated (intraperitoneally (i.p.) injected with 3 mg/kg body weight of sodium metavanadate and sacrificed every 3 months till 18 months); matched controls; and animals that were exposed to vanadium for 3 months and thereafter the metal was withdrawn. Brain tissues were obtained after animal sacrifice. Sagittal cut sections of paraffin embedded tissue (5 μm) were analyzed by the Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to show the absorption and distribution of vanadium metal. Also, Haematoxylin and Eosin (H&E) staining of brain sections, and immunohistochemistry for Microglia (Iba-1), Astrocytes (GFAP), Neurons (Neu-N) and Neu-N + 4',6-diamidine-2'-pheynylindole dihydrochloride (Dapi) Immunofluorescent labeling were observed for morphological and morphometric parameters. The LA-ICP-MS results showed progressive increase in vanadium uptake with time in different brain regions with prediction for regions like the olfactory bulb, brain stem and cerebellum. The withdrawal brains still show presence of vanadium metal in the brain slightly more than the controls. There were morphological alterations (of the layering profile, nuclear shrinkage) in the prefrontal cortex, cellular degeneration (loss of dendritic arborization) and cell death in the Hippocampal CA1 pyramidal cells and Purkinje cells of the cerebellum, including astrocytic and microglial activation in vanadium exposed brains which were all attenuated in the withdrawal group. With exposure into old age, the evident neuropathology was microgliosis, while progressive astrogliosis became more attenuated. We have shown that chronic administration of vanadium over a lifetime in mice resulted in metal accumulation which showed regional variabilities with time. The metal profile and pathological effects were not completely eliminated from the brain even after a long time withdrawal from vanadium metal.

Neuroprotective Effect of Grewia carpinifolia Extract against Vanadium Induced Behavioural Impairment

Vanadium (V), a heavy metal, has been reported to induce central nervous system toxicity leading to various behavioural impairments. It is characterized by the production of reactive oxygen. The present study was designed to test the possibility of Grewia carpinifolia ethanolic extract in preventing behavioural alterations following acute vanadium toxicity in mice. Twenty five Swiss albino mice (25—27 g) were completely randomized into 5 groups (A—E) of 5 animals each. Group A received distilled water and served as a control; group B, received vitamin E (500 mg.kg−1 b. w. every 72 hours), a known antioxidant orally, along with a daily dose of sodium metavanadate intraperitoneally (i. p.) for 7 days; group C and group D received Grewia carpinifolia leaf extract at 100 and 200 mg.kg−1 b.w orally respectively, along with the sodium metavanadate i. p. for 7 days; while group E received sodium metavanadate i. p. only for 7 days. The behavioural and motor functions were analysed by the open field, negative geotaxis, and hanging wire tests; the daily body and brain weights were recorded. Grewia carpinifolia ethanolic extracts significantly reduced the number of grooming, stretched attend posture, and freezing time that were significantly increased in the vanadium only group and also enhanced the vestibular functions. In addition, the latent time spent on the hanging wire in groups simultaneously administered with the extract and V compared favourably (P > 0.05) with the control groups but a decrease in latent time was observed in the V only group. The results suggest that acute V toxicity results in various behavioural deficits and support a possible role of Grewia carpinifolia as a protective agent against acute vanadium-toxicity with a better result at 200 mg.kg−1 b. w.

Regional Myelin and Axon Damage and Neuroinflammation in the Adult Mouse Brain After Long-Term Postnatal Vanadium Exposure

Environmental exposure to vanadium occurs in areas of persistent burning of fossil fuels; this metal is known to induce oxidative stress and oligodendrocyte damage. Here, we determined whether vanadium exposure (3 mg/kg) in mice during the first 3 postnatal months leads to a sustained neuroinflammatory response. Body weight monitoring, and muscle strength and open field tests showed reduction of body weight gain and locomotor impairment in vanadium-exposed mice. Myelin histochemistry and immunohistochemistry for astrocytes, microglia, and nonphosphorylated neurofilaments revealed striking regional heterogeneity. Myelin damage involved the midline corpus callosum and fibers in cortical gray matter, hippocampus, and diencephalon that were associated with axonal damage. Astrocyte and microglial activation was identified in the same regions and in the internal capsule; however, no overt myelin and axon damage was observed in the latter. Double immunofluorescence revealed induction of high tumor necrosis factor (TNF) immunoreactivity in reactive astrocytes. Western blotting analysis showed significant induction of TNF and interleukin-1β expression. Together these findings show that chronic postnatal vanadium exposure leads to functional deficit and region-dependent myelin damage that does not spare axons. This injury is associated with glial cell activation and proinflammatory cytokine induction, which may reflect both neurotoxic and neuroprotective responses.

Neurobehavioral and cytotoxic effects of vanadium during oligodendrocyte maturation: a protective role for erythropoietin

Vanadium exposure has been known to lead to lipid peroxidation, demyelination and oligodendrocytes depletion. We investigated behaviour and glial reactions in juvenile mice after early neonatal exposure to vanadium, and examined the direct effects of vanadium in oligodendrocyte progenitor cultures from embryonic mice. Neonatal pups exposed to vanadium via lactation for 15 and 22 days all had lower body weights. Behavioural tests showed in most instances a reduction in locomotor activity and negative geotaxis. Brain analyses revealed astrocytic activation and demyelination in the vanadium exposed groups compared to the controls. In cell culture, exposure of oligodendrocytes to 300 μM sodium metavanadate significantly increased cell death. Expression of the oligodendrocyte specific proteins, 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and oligodendrocyte specific protein (OSP/Claudin) were reduced upon vanadium treatment while simultaneous administration of erythropoietin (EPO; 4-12 U/ml) counteracted vanadium-toxicity. The data suggest that oligodendrocyte damage may explain the increased vulnerability of the juvenile brain to vanadium and support a potential for erythropoietin as a protective agent against vanadium-toxicity during perinatal brain development and maturation.

Effects of sodium metavanadate on in vitro neuroblastoma and red blood cells

Toxicity of vanadium on cells is one of the less studied effects. This prompted us to study the structural effects induced on neuroblastoma and erythrocytes by vanadium (V) sodium metavanadate. This salt was incubated with mice cholinergic neuroblastoma cells and intact human erythrocytes. To learn whether metavanadate interacts with membrane lipid bilayers it was incubated with bilayers built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE). These are phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. Exposure of neuroblastoma cells to metavanadate showed significant decreases in cell viability as well as in cell number correlating with inhibition of aconitase activity. In scanning electron microscopy (SEM) and defocusing microscopy (DM) it was observed that induced on erythrocytes the formation of echinocytes. However, no effects were obtained when metavanadate was made to interact with DMPC and DMPE multibilayers and liposomes, assays performed by X-ray diffraction and differential scanning calorimetry (DSC), respectively. These results imply that the effects of metavanadate on erythrocytes are through interactions with proteins located in the membrane outer moiety, and could still involve other minor lipid components as well. Also, partly unsaturated lipids could interact differently the fully saturated chains in the model systems.

Astrogliosis and HSP 70 activation in neonate rats' brain exposed to sodium metavanadate through lactation

The effect of sodium metavanadate (NaVO3) exposure on lipid oxidative damage in the CNS of suckling rats was studied. Using histological markers of cellular injury, we also studied the morphological alterations of neurons and astroglial cells in different regions of neonate rats CNS after NaVO3 exposure. Dams of treated litters were intraperitoneally injected with 3mgNaVO3/kgbody weight/day during 12days starting on post-natal day (PND) 10. On the 21st PND, four pups of each litter were sacrificed by decapitation and six brain areas were removed for lipid peroxidation assay by the thiobarbituric acid (TBA) reaction, the other four were transcardially perfused-fixed and their brains were removed and cut with a cryostat. Brain sections were processed for: NADPHd histochemistry and anti-HSP70, anti-GFAP and anti-S100 immunohistochemistry. The relative optical density of the NADPHd stained layers and of S100 (+) astrocytes and the GFAP (+) astrocyte surface area in Cer and Hc were measured. Although MDA levels, S100 immunostaining and NADPHd activity didn't show differences between experimental and control groups, both astrogliosis and HSP70 activation were detected in Cer, while only the former was detected in Hc of V-exposed pups.

Vanadium exposure-induced neurobehavioral alterations among Chinese workers

Vanadium-containing products are manufactured and widely used in the modern industry. Yet the neurobehavioral toxicity due to occupational exposure to vanadium remained elusive. This cross-sectional study was designed to examine the neurotoxic effects of occupational vanadium exposure. A total of 463 vanadium-exposed workers (exposed group) and 251 non-exposed workers (control group) were recruited from a Steel and Iron Group in Sichuan, China. A WHO-recommended neurobehavioral core test battery (NCTB) and event-related auditory evoked potentials test (P300) were used to assess the neurobehavioral functions of all study subjects. A general linear model was used to compare outcome scores between the two groups while controlling for possible confounders. The exposed group showed a statistically significant neurobehavioral alteration more than the control group in the NCTB tests. The exposed workers also exhibited an increased anger-hostility, depression-dejection and fatigue-inertia on the profile of mood states (p<0.05). Performances in the simple reaction time, digit span, benton visual retention and pursuit aiming were also poorer among exposed workers as compared to unexposed control workers (p<0.05). Some of these poor performances in tests were also significantly related to workers' exposure duration. P300 latencies were longer in the exposed group than in the control (p<0.05). Longer mean reaction times and more counting errors were also found in the exposed workers (p<0.05). Given the findings of our study and the limitations of neurobehavioral workplace testing, we found evidence of altered neurobehavioral outcomes by occupational exposure to vanadium.

Reversal of vanadium-induced toxicity by combination therapy of tiferron and α-tocopherol in rat during pregnancy and their fetuses

OBJECTIVE

The aim of this study was to analyze the effect of tiferron (sodium 4, 5-dihydroxybenzene-1, 3-disulfonate) per se and combination with α-tocopherol against vanadium induced developmental toxicity. Vanadium, as vanadyl sulphate pentahydrate, was evaluated for embryotoxic/fetotoxic effect in female albino rats (Sprague Dawley).

METHODS

The compound was administered by gavage to pregnant animals at a dose of 15 mg/kg/day, p.o. on day 6-15 of pregnancy (organogenesis). Tiferron was given on day 16-18 as chelating agent. Cesarean sections were performed on day 19 of gestation.

RESULTS

Maternal toxicity was observed, the level of sugar in the blood decreased, while we observed an increase in serum protein, serum alkaline phosphatase and serum transaminase activity. Level of lipid peroxidation showed enhances value in fetal and maternal liver. Vanadium induced inhibition in glycogen contents. Protein contents were decreased in vital organs where as increased in uterus and placenta. There was increased activity of acid phosphatase with the concomitant decline in alkaline phosphatase, adenosine triphosphatase and succnic dehydrogenase after vanadium intoxication. Toxicant caused severe alteration in histopathological observation of maternal and fetal liver, kidney, uterus and placenta proving its toxic consequences at cellular level. Tiferron along with α-tocopherol dramatically reversed alterations of all variables towards control rather than individual treatment.

CONCLUSION

The combination therapy of tiferron and α-tocopherol played a beneficial role in reducing vanadium induced developmental toxicity.

Human erythrocytes and neuroblastoma cells are in vitro affected by sodium orthovanadate

Research on biological influence of vanadium has gained major importance because it exerts potent toxic, mutagenic, and genotoxic effects on a wide variety of biological systems. However, hematological toxicity is one of the less studied effects. The lack of information on this issue prompted us to study the structural effects induced on the human erythrocyte membrane by vanadium (V). Sodium orthovanadate was incubated with intact erythrocytes, isolated unsealed human erythrocyte membranes (IUM) and molecular models of the erythrocyte membrane. The latter consisted of bilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. This report presents evidence in order that orthovanadate interacted with red cell membranes as follows: a) in scanning electron microscopy (SEM) studies it was observed that morphological changes on human erythrocytes were induced; b) fluorescence spectroscopy experiments in isolated unsealed human erythrocyte membranes (IUM) showed that an increase in the molecular dynamics and/or water content at the shallow depth of the lipids glycerol backbone at concentrations as low as 50μM was produced; c) X-ray diffraction studies showed that orthovanadate 0.25-1mM range induced increasing structural perturbation to DMPE; d) somewhat similar effects were observed by differential scanning calorimetry (DSC) with the exception of the fact that DMPC pretransition was shown to be affected; and e) fluorescence spectroscopy experiments performed in DMPC large unilamellar vesicles (LUV) showed that at very low concentrations induced changes in DPH fluorescence anisotropy at 18°C. Additional experiments were performed in mice cholinergic neuroblastoma SN56 cells; a statistically significant decrease of cell viability was observed on orthovanadate in low or moderate concentrations.

Local and systemic toxicity of nanoscale debris particles in total hip arthroplasty

Over the past 30 years joint replacement prostheses have been developed and refined to enhance durability and reproducibility. Total hip joint arthroplasty is being performed in an increasing number of younger patients; therefore orthopaedic surgeons seek implants with a longer life span. With regards to the progress of mechanical behaviour of the biomaterials used in an arthroplasty, little is known about the long-term biological effects of wear debris. Owing to the composition of the prostheses currently in use, systemic exposure to chromium (Cr), cobalt (Co), nickel (Ni) and aluminium (Al) alloys occurs as a result of the formation of metal wear nano-particles that are released both from metal-on-metal and polyethylene-on-metal bearings, resulting in a postoperative increase in metal ion levels at different organ sites. These particles circulate both locally and systemically, penetrate cell plasma membranes, bind to cellular proteins and enzymes and modulate cytokine expression. Their physiologic effects are poorly understood and their potential toxicity, hypersensitivity and carcinogenicity remain a cause for concern. In this article we will address the issue of whether these nanoscale degradation products are associated with adverse, clinically significant local or systemic toxicologic sequelae.

Toxic agents causing cerebellar ataxias

The cerebellum is particularly vulnerable to intoxication and poisoning, especially so the cerebellar cortex and Purkinje neurons. In humans, the most common cause of a toxic lesion to the cerebellar circuitry is alcohol related, but the cerebellum is also a main target of drug exposure (such as anticonvulsants, antineoplastics, lithium salts, calcineurin inhibitors), drug abuse and addiction (such as cocaine, heroin, phencyclidine), and environmental toxins (such as mercury, lead, manganese, toluene/benzene derivatives). Although data for the prevalence and incidence of cerebellar lesions related to intoxication and poisoning are still unknown in many cases, clinicians should keep in mind the list of agents that may cause cerebellar deficits, since toxin-induced cerebellar ataxias are not rare in daily practice. Moreover, the patient's status may require immediate therapies when the intoxication is life-threatening.

Nicotine attenuates spatial learning deficits induced by sodium metavanadate

Learning can be severely impaired as a consequence of exposure to environmental pollutants. Vanadium (V), a metalloid which is widely distributed in the environment, has been shown to exert toxic effects on a variety of biological systems including the nervous system. However, studies exploring the impact of vanadium on learning are limited. Herein, we investigated the effects of oral administration of sodium metavanadate (SMV) (15, 20 and 25mg/kg/day for 2weeks) on spatial learning using Morris water maze (MWM). Our results showed that pre-training administration of sodium metavanadate impaired learning in Morris water maze. Analyzing the role of cholinergic system in SMV-induced learning deficit, we found that bilateral intra-hippocampal infusion of nicotine (1μg/side) during training could significantly diminish the SMV-induced learning impairment. We next examined the expression of choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) as cholinergic markers in CA1 region of hippocampus as well as in medial septal area (MSA). Our molecular analyses showed that vanadium administration decreased ChAT and VAChT protein expression, an effect that was attenuated by nicotine. Altogether, our results confirmed the toxic effects of SMV on spatial acquisition, while also pointing to the neuroprotective effects of nicotine on SMV-induced impairments in learning capabilities. These findings might open a new avenue for the prevention of vanadium adverse effects on spatial learning and memory through activation of cholinergic signaling pathway.

Hypoglycemic Properties of Oxovanadium (IV) Coordination Compounds with Carboxymethyl-Carrageenan and Carboxymethyl-Chitosan in Alloxan-Induced Diabetic Mice

In order to avoid low absorption, incorporation, and undesirable side effects of inorganic oxovanadium compounds, the antidiabetic activities of organic oxovanadium (IV) compounds in alloxan-induced diabetic mice were investigated. Vanadyl carboxymethyl carrageenan (VOCCA) and vanadyl carboxymethyl chitosan (VOCCH) were synthesized and administrated through intragastric administration in different doses for 20 days in alloxan-induced diabetic mice. Glibenclamide was administrated as the positive control. Our results showed that low-dose group, middle-dose group, and high-dose group of VOCCA and VOCCH could significantly reduce the levels of blood glucose (P < 0.05) compared with untreated group, but not in normal mice. Besides, high-dose groups of VOCCA and VOCCH exhibited more significant hypoglycemic activities (P < 0.01). After treated with VOCCH, the oral glucose tolerance of high-dose group of VOCCH was improved compared with model control group (P < 0.05).

Orthopaedic metals and their potential toxicity in the arthroplasty patient

The long-term effects of metal-on-metal arthroplasty are currently under scrutiny because of the potential biological effects of metal wear debris. This review summarises data describing the release, dissemination, uptake, biological activity, and potential toxicity of metal wear debris released from alloys currently used in modern orthopaedics. The introduction of risk assessment for the evaluation of metal alloys and their use in arthroplasty patients is discussed and this should include potential harmful effects on immunity, reproduction, the kidney, developmental toxicity, the nervous system and carcinogenesis.