Memory Deficit Recovery after Chronic Vanadium Exposure in Mice

Diphenyl Diselenide Through Reduction of Inflammation, Oxidative Injury and Caspase-3 Activation Abates Doxorubicin-Induced Neurotoxicity in Rats

Neurotoxicity associated with chemotherapy is a debilitating side effect of cancer management in humans which reportedly involves inflammatory and oxidative stress responses. Diphenyl diselenide (DPDS) is an organoselenium compound which exhibits its anti-tumoral, anti-oxidant, anti-inflammatory and anti-mutagenic effects. Nevertheless, its possible effect on chemotherapy-induced neurotoxicity is not known. Using rat model, we probed the behavioral and biochemical effects accompanying administration of antineoplastic agent doxorubicin (7.5 mg/kg) and DPDS (5 and 10 mg/kg). Anxiogenic-like behavior, motor and locomotor insufficiencies associated with doxorubicin were considerably abated by both DPDS doses with concomitant enhancement in exploratory behavior as demonstrated by reduced heat maps intensity and enhanced track plot densities. Moreover, with exception of cerebral glutathione (GSH) level, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, biochemical data demonstrated reversal of doxorubicin-mediated decline in cerebral and cerebellar antioxidant status indices and the increase in acetylcholinesterase (AChE) activity by both doses of DPDS. Also, cerebellar and cerebral lipid peroxidation, hydrogen peroxide as well as reactive oxygen and nitrogen species levels were considerably diminished in rats administered doxorubicin and DPDS. In addition, DPDS administration abated myeloperoxidase activity, tumour necrosis factor alpha and nitric oxide levels along with caspase-3 activity in doxorubicin-administered rats. Chemoprotection of doxorubicin-associated neurotoxicity by DPDS was further validated by histomorphometry and histochemical staining. Taken together, DPDS through offsetting of oxido-inflammatory stress and caspase-3 activation elicited neuroprotection in doxorubicin-treated rats.

Neurobehavioral deficits, histoarchitectural alterations, parvalbumin neuronal damage and glial activation in the brain of male Wistar rat exposed to Landfill leachate

Concerns about inappropriate disposal of waste into unsanitary municipal solid waste landfills around the world have been on the increase, and this poses a public health challenge due to leachate production. The neurotoxic effect of Gwagwalada landfill leachate (GLL) was investigated in male adult Wistar rats. Rats were exposed to a 10% concentration of GLL for 21 days. The control group received tap water for the same period of the experiment. Our results showed that neurobehavior, absolute body and brain weights and brain histomorphology as well as parvalbumin interneurons were severely altered, with consequent astrogliosis and microgliosis after 21 days of administrating GLL. Specifically, there was severe loss and shrinkage of Purkinje cells, with their nucleus, and severe diffused vacuolations of the white matter tract of GLL-exposed rat brains. There was severe cell loss in the granular layer of the cerebellum resulting in a reduced thickness of the layer. Also, there was severe loss of dendritic arborization of the Purkinje cells in GLL-exposed rat brains, and damage as well as reduced populations of parvalbumin-containing fast-spiking GABAergic interneurons in various regions of the brain. In conclusion, data from the present study demonstrated the detrimental effects of Gwagwalada landfill leachate on the brain which may be implicated in neuropsychological conditions.

Amelioration of neurobehavioral, biochemical, and morphological alterations associated with silver nanoparticles exposure by taurine in rats

The adverse effect of silver nanoparticles (AgNPs) on the nervous system is an emerging concern of public interest globally. Taurine, an essential amino acid required for neurogenesis in the nervous system, is well-documented to possess antioxidant, anti-inflammatory, and antiapoptotic activities. Yet, there is no report in the literature on the effect of taurine on neurotoxicity related to AgNPs exposure. Here, we investigated the neurobehavioral and biochemical responses associated with coexposure to AgNPs (200 µg/kg body weight) and taurine (50 and 100 mg/kg body weight) in rats. Locomotor incompetence, motor deficits, and anxiogenic-like behavior induced by AgNPs were significantly alleviated by both doses of taurine. Taurine administration enhanced exploratory behavior typified by increased track plot densities with diminished heat maps intensity in AgNPs-treated rats. Biochemical data indicated that the reduction in cerebral and cerebellar acetylcholinesterase activity, antioxidant enzyme activities, and glutathione level by AgNPs treatment were markedly upturned by both doses of taurine. The significant abatement in cerebral and cerebellar oxidative stress indices namely reactive oxygen and nitrogen species, hydrogen peroxide, and lipid peroxidation was evident in rats cotreated with AgNPs and taurine. Further, taurine administration abated nitric oxide and tumor necrosis factor-alpha levels cum myeloperoxidase and caspase-3 activities in AgNPs-treated rats. Amelioration of AgNPs-induced neurotoxicity by taurine was confirmed by histochemical staining and histomorphometry. In conclusion, taurine via attenuation of oxido-inflammatory stress and caspase-3 activation protected against neurotoxicity induced by AgNPs in rats.

Epirubicin Treatment Induces Neurobehavioral, Oxido-Inflammatory and Neurohistology Alterations in Rats: Protective Effect of the Endogenous Metabolite of Tryptophan - 3-Indolepropionic Acid

Epirubicin's (EPI) efficacy as a chemotherapeutic agent against breast cancer is limited by EPI's neurotoxicity associated with increased oxidative and inflammatory stressors. 3-Indolepropionic acid (3-IPA) derived from in vivo metabolism of tryptophan is reported to possess antioxidative properties devoid of pro-oxidant activity. In this regard, we investigated the effect of 3-IPA on EPI-mediated neurotoxicity in forty female rats (180-200 g; five cohorts (n = 6) treated as follows: Untreated control; EPI alone (2.5 mg/Kg); 3-IPA alone (40 mg/Kg body weight); EPI (2.5 mg/Kg) + 3-IPA (20 mg/Kg) and EPI (2.5 mg/Kg) + 3-IPA (40 mg/Kg) for 28 days. Experimental rats were treated with EPI via intraperitoneal injection thrice weekly or co-treated with 3-IPA daily by gavage. Subsequently, the rat's locomotor activities were measured as endpoints of neurobehavioural status. After sacrifice, inflammation, oxidative stress and DNA damage biomarkers were assessed in rats' cerebrum and cerebellum alongside histopathology. Our results demonstrated that locomotor and exploratory deficits were pronounced in EPI-alone treated rats and improved in the presence of 3-IPA co-treatment. EPI-mediated decreases in tissue antioxidant status, increases in reactive oxygen and nitrogen species (RONS), as well as in lipid peroxidation (LPO) and xanthine oxidase (XO) were lessened in the cerebrum and cerebellum of 3-IPA co-treated rats. Increases in nitric oxide (NO) and 8-hydroxydeguanosin (8-OHdG) levels and myeloperoxidase MPO activity were also abated by 3-IPA. Light microscopic examination of the cerebrum and cerebellum revealed EPI-precipitated histopathological lesions were subsequently alleviated in rats co-treated with 3-IPA. Our findings demonstrate that supplementing endogenously derived 3-IPA from tryptophan metabolism enhances tissue antioxidant status, protects against EPI-mediated neuronal toxicity, and improves neurobehavioural and cognitive levels in experimental rats. These findings may benefit breast cancer patients undergoing Epirubicin chemotherapy.

Vanadium improves memory and spatial learning and protects the pyramidal cells of the hippocampus in juvenile hydrocephalic mice

Background

Hydrocephalus is a neurological condition known to cause learning and memory disabilities due to its damaging effect on the hippocampal neurons, especially pyramidal neurons. Vanadium at low doses has been observed to improve learning and memory abilities in neurological disorders but it is uncertain whether such protection will be provided in hydrocephalus. We investigated the morphology of hippocampal pyramidal neurons and neurobehavior in vanadium-treated and control juvenile hydrocephalic mice.

Methods

Hydrocephalus was induced by intra-cisternal injection of sterile-kaolin into juvenile mice which were then allocated into 4 groups of 10 pups each, with one group serving as an untreated hydrocephalic control while others were treated with 0.15, 0.3 and 3 mg/kg i.p of vanadium compound respectively, starting 7 days post-induction for 28 days. Non-hydrocephalic sham controls (n = 10) were sham operated without any treatment. Mice were weighed before dosing and sacrifice. Y-maze, Morris Water Maze and Novel Object Recognition tests were carried out before the sacrifice, the brains harvested, and processed for Cresyl Violet and immunohistochemistry for neurons (NeuN) and astrocytes (GFAP). The pyramidal neurons of the CA1 and CA3 regions of the hippocampus were assessed qualitatively and quantitatively. Data were analyzed using GraphPad prism 8.

Results

Escape latencies of vanadium-treated groups were significantly shorter (45.30 ± 26.30 s, 46.50 ± 26.35 s, 42.99 ± 18.44 s) than untreated group (62.06 ± 24.02 s) suggesting improvements in learning abilities. Time spent in the correct quadrant was significantly shorter in the untreated group (21.19 ± 4.15 s) compared to control (34.15 ± 9.44 s) and 3 mg/kg vanadium-treated group (34.35 ± 9.74 s). Recognition index and mean % alternation were lowest in untreated group (p = 0.0431, p=0.0158) suggesting memory impairments, with insignificant improvements in vanadium-treated groups. NeuN immuno-stained CA1 revealed loss of apical dendrites of the pyramidal cells in untreated hydrocephalus group relative to control and a gradual reversal attempt in the vanadium-treated groups. Astrocytic activation (GFAP stain) in the untreated hydrocephalus group were attenuated in the vanadium-treated groups under the GFAP stain. Pyknotic index in CA1 pyramidal layer of untreated (18.82 ± 2.59) and 0.15mg/kg vanadium-treated groups (18.14 ± 5.92) were significantly higher than control (11.11 ± 0.93; p = 0.0205, p = 0.0373) while there was no significant difference in CA3 pyknotic index across all groups.

Conclusion

Our results suggest that vanadium has a dose-dependent protective effect on the pyramidal cells of the hippocampus and on memory and spatial learning functions in juvenile hydrocephalic mice.

Neurobehavioral and biochemical responses to artemisinin-based drug and aflatoxin B1 co-exposure in rats

Populations in malaria endemic areas are frequently exposed to mycotoxin-contaminated diets. The possible toxicological outcome of co-exposure to dietary aflatoxin B₁ (AFB₁) and artemisinin-based combination therapy warrants investigation to ascertain amplification or attenuation of cellular injury. Here, we investigated the neurobehavioral and biochemical responses associated with co-exposure to anti-malarial drug coartem, an artemether-lumefantrine combination (5 mg/kg body weight, twice a day and 3 days per week) and AFB₁ (35 and 70 µg/kg body weight) in rats. Motor deficits, locomotor incompetence, and anxiogenic-like behavior induced by low AFB₁ dose were significantly (p < 0.05) assuaged by coartem but failed to rescue these behavioral abnormalities in high AFB₁-dosed group. Coartem administration did not alter exploratory deficits typified by reduced track plot densities and greater heat map intensity in high AFB₁-dosed animals. Furthermore, the reduction in cerebral and cerebellar acetylcholinesterase activity, anti-oxidant enzyme activities, and glutathione and thiol levels were markedly assuaged by coartem administration in low AFB₁ group but not in high AFB₁-dosed animals. The significant attenuation of cerebral and cerebellar oxidative stress indices namely reactive oxygen and nitrogen species, xanthine oxidase activity, and lipid peroxidation by coartem administration was evident in low AFB₁ group but not high AFB₁ dose. Although coartem administration abated nitric oxide level, activities of myeloperoxidase, caspase-9, and caspase-3 in animals exposed to both doses of AFB₁, these indices were significantly higher than the control. Coartem administration ameliorated histopathological and mophometrical changes due to low AFB₁ exposure but not in high AFB₁ exposure. In conclusion, contrary to AFB₁ alone, behavioral and biochemical responses were not altered in animals singly exposed to coartem. Co-exposure to coartem and AFB₁ elicited no additional risk but partially lessened neurotoxicity associated with AFB₁ exposure.

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.

Neurobehavioral effects of chronic low-dose vanadium administration in young male rats

Exposure to the metal vanadium, in both animals and humans has been linked to various physiological consequences including respiratory and gastrointestinal conditions. Research on the neurobehavioral effects of vanadium exposure is limited. Hence, the purpose of the current study was to examine the effects of chronic low-dose vanadium administration (0.04 mg/week) on the behavior of young male rats. Four weeks following the administration of vanadium, rats were tested on the open field, object recognition, and Morris Water maze tasks. Vanadium did not affect exploration, locomotion, or anxiety-like behavior as measured by the open field task. Vanadium administration affected novel object recognition performance. Intriguingly, rats exposed to vanadium exhibited lower latency times on day 2 of the Morris Water maze. These findings suggest that vanadium's behavioral effects are complex and warrant further investigation to better understand the potential benefits and consequences of its exposure.

Vanadium pollution and health risks in marine ecosystems: Anthropogenic sources over natural contributions

Vanadium has been classified as a potentially toxic metal and has been given limited attention in comparison to similar trace metals. Similarly, worldwide and continental vanadium pollution and risks remain contested. Here, we synthesized the worldwide concentration of vanadium in marine ecosystems with the relevant ecological and human health risks. We found that vanadium in biota and seawater collected from Asia shows significant increases over the temporal analysis, with rates similar to those reported for vanadium consumption and production. Furthermore, invertebrates have a higher concentration of vanadium than fishes. Similarly, we demonstrate that sediments classified as polluted have concentrations that are not directly correlated with the highest concentrations across continents. Finally, ecological risks were higher from seawater, with potential impacts to 55% of aquatic species in Asia estimated from chronic species sensitivity distribution (SSD). The concentration endangering only 5% of seawater species (HC5) was estimated as 1.13 (0.05-21.19) μg L^-1. Estimated daily intakes revealed that overall, there are none to low health risks from aquatic product consumption, yet high risks are plausible to children with consumption patterns in the 95th percentile.

Ameliorative effects of the aqueous extract of Khaya anthotheca (Welw.) C.DC (Meliaceae) in vanadium induced anxiety, memory loss and pathologies in the brain and ovary of mice

ETHNOPHARMACOLOGICAL RELEVANCE

Ethnobotanical enquiries have revealed that Khaya anthotheca (Welw.) C.DC (Meliaceae) has anxiolytic properties and is used to alleviate vaginal dryness in postmenopausal women in Cameroon. The aim of this study was to evaluate the ameliorative effects of the aqueous extract of K. anthotheca in vanadium induced anxiety, memory loss and pathologies in the brain and ovary of mice.

MATERIAL AND METHODS

Forty neonatal female mice were used in this study. All animals received vanadium (3 mg/kg BW/72 h, by lactation and i.p.) for 20 weeks except the Control group. At 16 weeks old, mice were divided into 5 groups (n = 8): Control group received distilled water; V-group received vanadium (V) (3 mg/kg BW every 72 h i.p.), V + Vit E group received vitamin E (500 mg/kg BW/72 h) and vanadium (V) (3 mg/kg BW/72 h i.p, simultaneously). V + KA 125 and V + KA 250 groups received K. anthotheca extract at the doses of 125 and 250 mg/kg BW/day respectively and vanadium (V) (3 mg/kg BW/72 h i.p, simultaneously).The treatment was done per os at 10 mL/kg of volume of administration for 4 weeks. To evalute anxiolytic effects and spatial working memory improved by the extract in mice, the elevated open space test and Y maze test were used respectively. After sacrifice, brains were harvested and pathologies were assessed using cresyl violet stainning and immunohistochemistry (GFAP, Iba-1 and MBP), while pathologies in the ovaries were assessed using immunohistochemistry (Collagen type 1) and H&E stainning.

RESULTS

Results in the three sessions of elevated open space test showed that vanadium exposure resulted in a significant (p < 0.05; p < 0.01) increase of the latency of first entry in the slopes and a significant (p < 0.05; p < 0.01; p < 0.001) decrease of the time spent and number of entries in the slopes however, Khaya anthotheca treatment induced a significant (p < 0.05; p < 0.01) decrease of the latency of first entry in the slopes and a significant (p < 0.05; p < 0.01) increase of the time spent and number of entries in the slopes. In the Y maze test, vanadium exposure resulted in a significant decrease (p < 0.01) in the percentage of correct alternation, K. anthotheca extract at the dose of 250 mg/kg BW however induced a significant (p < 0.05) increase of this percentage of correct spontaneous alternation. In the brain, degeneration induced by vanadium exposure was marked by an increase of GFAP-immunoreactive cells, microgliosis and demyelination. The treatment with Khaya anthotheca extract at the dose of 250 mg/kg BW resulted in the preservation of cellular integrity in the same anatomical regions with reduced astroglial and microglial activation and prevented demyelination. In addition, vanadium exposure decreased Collagen type 1 expression in the ovaries and induced a deterioration of tertiary follicle. Khaya anthotheca treatment at the dose of 250 mg/kg BW induced an increase of expression of Collagen type 1 and alleviated deterioration of the microarchitecture of tertiary follicle induced by vanadium.

CONCLUSION

These effects induced by K. anthotheca extract could justify the traditional use of this plant in Cameroonian traditional medicine to manage anxiety. Therefore, to minimise vanadium induced toxicity, the plant should be given more emphasis as a candidate in developing a modern phytodrug.

Neuroprotective role of gallic acid in aflatoxin B1 -induced behavioral abnormalities in rats

The neurotoxic impact of dietary exposure to aflatoxin B₁ (AFB₁ ) is documented in experimental and epidemiological studies. Gallic acid (GA) is a triphenolic phytochemical with potent anticancer, anti-inflammatory, and antioxidant activities. There is a knowledge gap on the influence of GA on AFB₁ -induced neurotoxicity. This study probed the influence of GA on neurobehavioral and biochemical abnormalities in rats orally treated with AFB₁ per se (75 µg/kg body weight) or administered together with GA (20 and 40 mg/kg) for 28 uninterrupted days. Behavioral endpoints obtained with video-tracking software demonstrated significant (p < .05) abatement of AFB₁ -induced anxiogenic-like behaviors (increased freezing, urination, and fecal bolus discharge), motor and locomotor inadequacies, namely increased negative geotaxis and diminished grip strength, absolute turn angle, total time mobile, body rotation, maximum speed, and total distance traveled by GA. The improvement of exploratory behavior in animals that received both AFB₁ and GA was confirmed by track plots and heat maps appraisal. Abatement of AFB₁ -induced decreases in acetylcholinesterase activity, antioxidant status and glutathione level by GA was accompanied by a marked reduction in oxidative stress markers in the cerebellum and cerebrum of rats. Additionally, GA treatment abrogated AFB₁ -mediated decrease in interleukin-10 and elevation of inflammatory indices, namely tumor necrosis factor-α, myeloperoxidase activity, interleukin-1β, and nitric oxide. Further, GA treatment curtailed caspase-3 activation and histological injuries in the cerebral and cerebellar tissues. In conclusion, abatement of AFB₁ -induced neurobehavioral abnormalities by GA involves anti-inflammatory, antioxidant, and antiapoptotic mechanisms in rats.

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.

In vitro effect of vanadyl sulfate on cultured primary astrocytes: cell viability and oxidative stress markers

Exposure to vanadium has been associated with deleterious effects on the central nervous system in animals and humans. Although vanadium-derived pro-oxidant species were reported to be involved in vanadium-mediated neurotoxicity, the ability of this metal to induce oxidative stress markers in glial cells remains to be elucidated. In this study, we investigated the cytotoxicity and the generation of reactive oxygen species (ROS) and nitric oxide (NO) by mouse primary astrocytes after treatment with vanadyl sulfate (VOSO₄ ) at concentrations of 20, 50, 100, 200, and 500 μM. The resazurin assay revealed that treatment with VOSO₄ for 24 and 48 h at concentrations of 50 and 100 μM, respectively, or higher substantially induced astrocytic cytotoxicity. Intracellular ROS increased after 6-h exposure to the lowest concentration tested (20 μM VOSO₄ ) and tended to intensify after 24- and 48-h treatments reaching significant values for 20 and 500 μM VOSO₄ . In turn, NO production in the examined cells was elevated after exposure to all concentrations at the 6-, 24-, and 48-h incubation periods. Our study demonstrated the ability of VOSO₄ to induce H₂ O₂ generation in cell-free DMEM/F12 medium. The H₂ O₂ levels were in the micromolar range (up to 5 μM) and were detected mostly during the first few minutes after VOSO₄ addition, suggesting that the generated H₂ O₂ could not induce toxic effects on the cells. Taken together, these results show VOSO₄ induced cytotoxicity in primary astrocyte cells, which may have resulted from vanadyl-stimulated intracellular ROS and NO generation in these cells.

Protective Effects of Dietary Antioxidants against Vanadium-Induced Toxicity: A Review

Vanadium (V) in its inorganic forms is a toxic metal and a potent environmental and occupational pollutant and has been reported to induce toxic effects in animals and people. In vivo and in vitro data show that high levels of reactive oxygen species are often implicated in vanadium deleterious effects. Since many dietary (exogenous) antioxidants are known to upregulate the intrinsic antioxidant system and ameliorate oxidative stress-related disorders, this review evaluates their effectiveness in the treatment of vanadium-induced toxicity. Collected data, mostly from animal studies, suggest that dietary antioxidants including ascorbic acid, vitamin E, polyphenols, phytosterols, and extracts from medicinal plants can bring a beneficial effect in vanadium toxicity. These findings show potential preventive effects of dietary antioxidants on vanadium-induced oxidative stress, DNA damage, neurotoxicity, testicular toxicity, and kidney damage. The relevant mechanistic insights of these events are discussed. In summary, the results of studies on the role of dietary antioxidants in vanadium toxicology appear encouraging enough to merit further investigations.

Neurobehavioural and biochemical responses associated with exposure to binary waterborne mixtures of zinc and nickel in rats

Environmental and occupational exposure to metal mixtures due to various geogenic and anthropogenic activities poses a health threat to exposed organisms. The outcome of systemic interactions of metals is a topical area of research because it may cause either synergistic or antagonistic effect. The present study investigated the impact of co-exposure to environmentally relevant concentrations of waterborne nickel (75 and 150 μg NiCl ₂ L^-1) and zinc (100 and 200 μg ZnCl₂ L^-1) mixtures on neurobehavioural performance of rats. Locomotor, motor and exploratory activities were evaluated using video-tracking software during trial in a novel arena and thereafter, biochemical and histological analyses were performed using the cerebrum, cerebellum and liver. Results indicated that zinc significantly (p < 0.05) abated the nickel-induced locomotor and motor deficits as well as improved the exploratory activity of exposed rats as verified by track plots and heat map analyses. Moreover, zinc mitigated nickel-mediated decrease in acetylcholinesterase activity, elevation in biomarkers of liver damage, levels of reactive oxygen and nitrogen species as well as lipid peroxidation in the exposed rats when compared with control. Additionally, nickel mediated decrease in antioxidant enzyme activities as well as the increase in tumour necrosis factor alpha, interleukin-1 beta and caspase-3 activity were markedly abrogated in the cerebrum, cerebellum and liver of rats co-exposed to nickel and zinc. Histological and histomorphometrical analyses evinced that zinc abated nickel-mediated neurohepatic degeneration as well as quantitative reduction in the widest diameter of the Purkinje cells and the densities of viable granule cell layer of dentate gyrus, pyramidal neurones of cornu ammonis 3 and cortical neurons in the exposed rats. Taken together, zinc abrogated nickel-induced neurohepatic damage via suppression of oxido-inflammatory stress and caspase-3 activation in rats.

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.

Βeta-sitosterol enhances motor coordination, attenuates memory loss and demyelination in a vanadium-induced model of experimental neurotoxicity

Environmental discharge of vanadium causes cognitive and behavioral impairments in humans and animals via production of reactive oxygen species leading to lipid peroxidation and alteration in antioxidant defence system. The current study was carried out to investigate the cognitive-enhancing ability of β-sitosterol in vanadium-induced neurotoxicity. Forty eight mice were randomly assigned into 4 groups (A-D) with the following treatments: group A; distilled water, B; α-tocopherol + sodium metavanadate (NaO₃V), C; β-sitosterol + NaO₃V and D; only NaO₃V. NaO₃V was administered intraperitoneally while other treatments were administered through gavage for 7 consecutive days. Neurobehavioral parameters measuring cognition, locomotion, anxiety and grip strength were evaluated at day 8. Following sacrifice, brain levels of catalase, superoxide dismutase, glutathione, malonaldehyde (MDA) and hydrogen peroxide (H₂O₂) were measured. Immunohistochemical expression of Myelin Basic Protein (MBP) in the brain was also investigated. The results showed that deficits in spatial learning, locomotor efficiency, and motor coordination, induced by acute vanadium neurotoxicity were mitigated by beta-sitosterol. Significantly (α ≤ 0.05) decreased in vivo antioxidant enzyme activities, increased brain levels of MDA and H₂O₂, structural damage to myelin sheaths and decreased expression of MBP were also observed in the NaO₃V group (D), however, co-administration of β-sitosterol reduced these pathologic features. It is concluded that β-sitosterol alleviates vanadium-induced neurotoxicity by enhancing cognition and improving motor co-ordination via its antioxidant and myelo-protective activities.

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.

Oligodendrocyte morphology in the developing brain of the African giant rat (Cricetomys gambianus, Waterhouse): Histology, immunohistochemistry and electron microscopy

Oligodendrocyte and myelin-related studies have been pivotal in understanding disruption of central nervous system (CNS) myelin through injury, toxicological, pathological degeneration or genetic intervention. The African giant rat (AGR) has been postulated as an indigenous wild-type model within the African context. This work thus describes oligodendrocyte morphologies and myelin components of the developing African giant rat brain using histological, immunohistochemical and ultrastructural techniques. Five types, precursor-progenitor oligodendrocytes, pre-oligodendrocytes, immature oligodendrocytes, mature non-myelinating oligodendrocytes and mature myelinating oligodendrocytes, were identified. The first four types were observed in neonates while juvenile and adult AGR had predominantly mature myelinating oligodendrocytes with evidence of myelin sheath deposition. All cell types identified showed positive CNPase-positive immunosignalling across all age groups. This suggests CNPase as a suitable, sensitive and reliable biomarker for studying CNS neurodegenerative/demyelinating disorders in the AGR. This baseline study has given detailed insight into the morphology of oligodendrocytes and myelin in the AGR. It may be useful for anatomical studies and detection of alterations in neurocellular profile of oligodendrocytes and myelin in the AGR in real-life or in experimental models.

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.