Zinc and Calcium Reduce Lead Induced Perturbations in the Aminergic System of Developing Brain

Zinc Oxide Nanoparticles Attenuated Neurochemical and Histopathological Alterations Associated with Aluminium Chloride Intoxication in Rats

The present investigation explored the potential neuroprotective role of zinc oxide nanoparticles (ZnONPs) on aluminum chloride (AlCl3)-mediated Alzheimer's disease (AD)-like symptoms. Rats were distributed into four treatment groups equally: control, ZnONPs (4 mg/kg b.wt.), AlCl3 (100 mg/kg b.wt.), and ZnONPs + AlCl3 groups. Rats were treated for 42 consecutive days. ZnONPs injection into AlCl3-treated rats suppressed the development of oxidative challenge in the cortical and hippocampal tissues, as demonstrated by the decreased neuronal pro-oxidants (malondialdehyde and nitric oxide), and the increased glutathione and catalase levels. Additionally, ZnONPs injection showed anti-inflammatory potency in response to AlCl3 by decreasing levels of tumor necrosis factor-α and interleukin-1β. Moreover, pretreatment with ZnONPs prevented neuronal cell loss by decreasing the level of pro-apoptotic caspase-3 and enhancing the anti-apoptotic B cell lymphoma 2. Furthermore, ZnONPs ameliorated the disturbed acetylcholinesterase activity, monoamines (norepinephrine, dopamine, and serotonin), excitatory (glutamic and aspartic acids), and inhibitory amino acids (GABA and glycine) in response to AlCl3 exposure. These findings indicate that ZnONPs may have the potential as an alternative therapy to minimize or prevent the neurological deficits in AD model by exhibiting antioxidative, anti-inflammation, anti-apoptosis, and neuromodulatory effects.

Apple phenolic extract ameliorates lead-induced cognitive impairment, depression- and anxiety-like behavior in mice through abating oxidative stress, inflammation and apoptosis via miR-22-3p/SIRT1 axis

Lead can lead to neurotoxicity and cognitive impairment. In this study, for the first time, the protective effects and working mechanisms of apple phenolic extract (APE) against lead acetate (Pb(Ac)2)-induced...

Transgenerational endocrine disruption: Does elemental pollution affect egg or nestling thyroid hormone levels in a wild songbird?

Endocrine disrupting chemicals (EDCs) include a wide array of pollutants, such as some metals and other toxic elements, which may cause changes in hormonal homeostasis. In addition to affecting physiology of individuals directly, EDCs may alter the transfer of maternal hormones to offspring, i.e. causing transgenerational endocrine disruption. However, such effects have been rarely studied, especially in wild populations. We studied the associations between environmental elemental pollution (As, Cd, Cu, Ni, Pb) and maternally-derived egg thyroid hormones (THs) as well as nestling THs in great tits (Parus major) using extensive sampling of four pairs of polluted and reference populations across Europe (Finland, Belgium, Hungary, Portugal). Previous studies in these populations showed that breeding success, nestling growth and adult and nestling physiology were altered in polluted zones compared to reference zones. We sampled non-incubated eggs to measure maternally-derived egg THs, measured nestling plasma THs and used nestling faeces for assessing local elemental exposure. We also studied whether the effect of elemental pollution on endocrine traits is dependent on calcium (Ca) availability (faecal Ca as a proxy) as low Ca increases toxicity of some elements. Birds in the polluted zones were exposed to markedly higher levels of toxic elements than in reference zones at the populations in Finland, Belgium and Hungary. In contrast to our predictions, we did not find any associations between overall elemental pollution, or individual element concentrations and egg TH and nestling plasma TH levels. However, we found some indication that the effect of metals (Cd and Cu) on egg THs is dependent on Ca availability. In summary, our results suggest that elemental pollution at the studied populations is unlikely to cause overall TH disruption and affect breeding via altered egg or nestling TH levels with the current elemental pollution loads. Associations with Ca availability should be further studied.

Crocus sativus restores dopaminergic and noradrenergic damages induced by lead in Meriones shawi: A possible link with Parkinson's disease

Lead (Pb) is a metal element released into the atmosphere and a major source of environmental contamination. The accumulation and concentration of this metal in a food web may lead to the intoxication of the body, more precisely, the nervous system (NS). In addition, Pb-exposure can cause structural and functional disruption of the NS. Studies have shown that Pb-exposure could be a risk factor in the development of Parkinson's disease (PD). The latter is related to dopaminergic deficiency that may be triggered by genetic and environmental factors such as Pb intoxication. In this study, we have evaluated, in one hand, the neurotoxic effect of Pb (25 mg / kg B.W i.p) for three consecutive days on dopaminergic system and locomotor performance in Merione shawi. In the other hand, the possible restorative potential of C. sativus (CS) (50 mg / kg BW) by oral gavage. The immunohistochemical approach has revealed that Pb-intoxicated Meriones show a significant increase of Tyrosine Hydroxylase (TH) levels within the Substantia Nigra compacta (SNc), Ventral Tegmental Area (VTA), Locus Coeruleus (LC), Dorsal Striatum (DS) and Medial Forebrain Bundle (MFB), unlike the control meriones, a group intoxicated and treated with Crocus sativus hydroethanolic extract (CSHEE) and treated group by CSHEE. Treatment with CSHEE, has shown a real potential to prevent all Pb-induced damages. In fact, restores the TH levels by 92%, 90%, 88%, 90% and 93% in SNc, VTA, LC, DS and MFB respectively, similarly, locomotor activity dysfunction in Pb-intoxicaed meriones was reinstated by 90%. In this study, we have revealed a new pharmacological potential of Crocus sativus that can be used as a neuroprotective product for neurodegenerative disorders, especially, which implying dopaminergic and noradrenergic injuries, like PD, trigged by heavy metals.

Progress in Research on Brain Development and Function of Mice During Weaning

Lactation is a critical phase for brain function development. New dietary experiences of mouse caused by weaning can regulate brain development and function, increase their response to food and environment, and eventually give rise to corresponding behavioral changes. Changes in weaning time induce the alteration of brain tissues morphology and molecular characteristics, glial cell activity and behaviors in the offspring. In addition, it is also sensitive to the intervention of environment and drugs during this period. That is to say, the study focused on brain development and function based on mouse weaning is critical to demonstrate the underlying pathogenesis of neuropsychiatric diseases and find new drug targets. This article mainly focuses on the developmental differentiation of the brain during lactation, especially during weaning in mice.

Effects of combined arsenic and lead exposure on the brain monoaminergic system and behavioral functions in rats: Reversal effect of MiADMSA

In this study, we evaluated the therapeutic efficacy of monoisoamyldimercaptosuccinic acid (MiADMSA) against individual and combined effects of arsenic (As) and lead (Pb) on the monoaminergic system and behavioral functions in rats. Pregnant rats were exposed to sodium metaarsenite (50 ppm) and lead acetate (0.2%) individually and in combination (As = 25 ppm + Pb = 0.1%) via drinking water from gestation day (GD) 6 to postnatal day (PND) 21. MiADMSA (50 mg/kg body weight) was given orally through gavage for 3 consecutive days to pups from PND 18 to PND 20. The results showed increases in synaptosomal epinephrine, dopamine, and norepinephrine levels with individual metal exposures and decreases with combined exposure to As and Pb in the cortex, cerebellum, and hippocampus in PND 21, PND 28, and 3 months age-group rats. We found decreased activity of mitochondrial monoamine oxidase in the selected brain regions following individual and combined exposures to Pb and As. In addition, rats treated with Pb and As alone or in combination showed significant deficits in open-field behavior, grip strength, locomotor activity, and exploratory behavior at PND 28 and 3 months of age. However, MiADMSA administration showed reversal effects against the As- and/or Pb-induced impairments in the monoaminergic system as well as in behavioral functions of rats. Our data demonstrated that the mixture of Pb and As induced synergistic toxicity to developing brain leading to impairments in neurobehavioral functions and also suggest therapeutic efficacy of MiADMSA against Pb- and/or As-induced developmental neurotoxicity.

Spirulina platensis attenuates the associated neurobehavioral and inflammatory response impairments in rats exposed to lead acetate

Heavy metals are well known as environmental pollutants with hazardous impacts on human and animal health because of their wide industrial usage. In the present study, the role of Spirulina platensis in reversing the oxidative stress-mediated brain injury elicited by lead acetate exposure was evaluated. In order to accomplish this aim, rats were orally administered with 300 mg/kg bw Spirulina for 15 d, before and simultaneously with an intraperitoneal injection of 50 mg/kg bw lead acetate [6 injections through the two weeks]. As a result, the co-administration of Spirulina with lead acetate reversed the most impaired open field behavioral indices; however, this did not happen for swimming performance, inclined plane, and grip strength tests. In addition, it was observed that Spirulina diminished the lead content that accumulated in both the blood and the brain tissue of the exposed rats, and reduced the elevated levels of oxidative damage indices, and brain proinflammatory markers. Also, because of the Spirulina administration, the levels of the depleted biomarkers of antioxidant status and interleukin-10 in the lead-exposed rats were improved. Moreover, Spirulina protected the brain tissue (cerebrum and cerebellum) against the changes elicited by lead exposure, and also decreased the reactivity of HSP70 and Caspase-3 in both cerebrum and cerebellum tissues. Collectively, our findings demonstrate that Spirulina has a potential use as a food supplement in the regions highly polluted with heavy metals.

Uranium exposure of human dopaminergic cells results in low cytotoxicity, accumulation within sub-cytoplasmic regions, and down regulation of MAO-B

Natural uranium is an ubiquitous element present in the environment and human exposure to low levels of uranium is unavoidable. Although the main target of acute uranium toxicity is the kidney, some concerns have been recently raised about neurological effects of chronic exposure to low levels of uranium. Only very few studies have addressed the molecular mechanisms of uranium neurotoxicity, indicating that the cholinergic and dopaminergic systems could be altered. The main objective of this study was to investigate the mechanisms of natural uranium toxicity, after 7-day continuous exposure, on terminally differentiated human SH-SY5Y cells exhibiting a dopaminergic phenotype. Cell viability was first assessed showing that uranium cytotoxicity only occurred at high exposure concentrations (> 125 μM), far from the expected values for uranium in the blood even after occupational exposure. SH-SY5Y differentiated cells were then continuously exposed to 1, 10, 125 or 250 μM of natural uranium for 7 days and uranium quantitative subcellular distribution was investigated by means of micro-PIXE (Particle Induced X-ray Emission). The subcellular element imaging revealed that uranium was located in defined perinuclear regions of the cytoplasm, suggesting its accumulation in organelles. Uranium was not detected in the nucleus of the differentiated cells. Quantitative analysis evidenced a very low intracellular uranium content at non-cytotoxic levels of exposure (1 and 10 μM). At higher levels of exposure (125 and 250 μM), when cytotoxic effects begin, a larger and disproportional intracellular accumulation of uranium was observed. Finally the expression of dopamine-related genes was quantified using real time qRT-PCR. The expression of monoamine oxidase B (MAO-B) gene was statistically significantly decreased after exposure to uranium while other dopamine-related genes were not modified. The down regulation of MAO-B was confirmed at the protein level. This original result suggests that the inhibition of dopamine catabolism, but also of other MAO-B substrates, could constitute selective effects of uranium neurotoxicity.

Attenuation of Lead-Induced Neurotoxicity by Omega-3 Fatty Acid in Rats

Background

Lead is widely distributed in the environment and has been found to be associated with various health problems including neurodegenerative diseases.

Purpose

In view of the increasing health risk caused by lead, this study has been carried out to investigate the neuroprotective effect of omega-3 fatty acid (omega-3FA) in lead-induced neurotoxicity in rats.

Methods

Biochemical parameters including oxidative stress in brain regions, lead levels in blood and brain regions and histopathological examination of brain regions of rats were carried out in the present study.

Results

Rats exposed to lead (lead acetate 7.5 mg/kg body weight p.o. for 14 days) caused a significant increase in the levels of lipid peroxidation, protein carbonyl content, ROS production and decreased the activities of glutathione peroxidase, superoxide dismutase and catalase in the cerebellum and cerebral cortex, respectively, as compared to controls. Abnormal histopathological changes and increase in the levels of lead in blood and brain were also observed as compared to controls. Co-treatment of lead with omega-3FA (750 mg/kg body weight p.o. for 14 days) decreased the levels of lipid peroxidation, protein carbonyl content, ROS production and increased the activities of glutathione peroxidase, superoxide dismutase and catalase and showed protection in the histopathological study as compared to rats treated with lead alone.

Conclusions

The result of the present study shows that lead-induced oxidative stress and histopathological alteration in the brain region were significantly protected with co-treatment of lead and omega-3FA. This could be due to its strong antioxidant potential and metal-binding property.

Dietary compounds as modulators of metals and metalloids toxicity

A large part of the population is exposed to metals and metalloids through the diet. Most of the in vivo studies on its toxicokinetics and toxicity are conducted by means of exposure through drinking water or by intragastric or intraperitoneal administration of aqueous standards, and therefore they do not consider the effect of the food matrix on the exposure. Numerous studies show that some components of the diet can modulate the toxicity of these food contaminants, reducing their effect on a systemic level. Part of this protective role may be due to a reduction of intestinal absorption and subsequent tissue accumulation of the toxic element, although it may also be a consequence of their ability to counteract the toxicity directly by their antioxidant and/or anti-inflammatory activity, among other factors. The present review provides a compilation of existing information about the effect that certain components of the diet have on the toxicokinetics and toxicity of the metals and metalloids of greatest toxicological importance that are present in food (arsenic, cadmium, lead, and mercury), and of their most toxic chemical species.

Zinc Improves Cognitive and Neuronal Dysfunction During Aluminium-Induced Neurodegeneration

Metals are considered as important components of a physiologically active cell, and imbalance in their levels can lead to various diseased conditions. Aluminium (Al) is an environmental neurotoxicant, which is etiologically related to several neurodegenerative disorders like Alzheimer's, whereas zinc (Zn) is an essential trace element that regulates a large number of metabolic processes in the brain. The objective of the present study was to understand whether Zn provides any physiological protection during Al-induced neurodegeneration. Male Sprague Dawley rats weighing 140-160 g received either aluminium chloride (AlCl₃) orally (100 mg/kg b.wt./day), zinc sulphate (ZnSO₄) in drinking water (227 mg/L) or combined treatment of aluminium and zinc for 8 weeks. Al treatment resulted in a significant decline in the cognitive behaviour of rats, whereas zinc supplementation caused an improvement in various neurobehavior parameters. Further, Al exposure decreased (p ≤ 0.001) the levels of neurotransmitters, acetylcholinesterase activity, but increased (p ≤ 0.001) the levels of L-citrulline as well as activities of nitric oxide and monoamine oxidase in the brain. However, zinc administration to Al-treated animals increased the levels of neurotransmitters and regulated the altered activities of brain markers. Western blot of tau, amyloid precursor protein (APP), glial fibrillary acidic protein (GFAP), ubiquitin, α-synuclein and Hsp 70 were also found to be elevated after Al exposure, which however were reversed following Zn treatment. Al treatment also revealed alterations in neurohistoarchitecture in the form of loss of pyramidal and Purkinje cells, which were improved upon zinc co-administration. Therefore, the present study demonstrates that zinc improves cognitive functions by regulating α-synuclein and APP-mediated molecular pathways during aluminium-induced neurodegeneration.

Zinc modulates aluminium-induced oxidative stress and cellular injury in rat brain

Dysregulation of metal homeostasis has been perceived as one of the key factors in the progression of neurodegeneration. Aluminium (Al) has been considered as a major risk factor, which is linked to several neurodegenerative diseases, especially Alzheimer's disease, whereas zinc (Zn) has been reported as a vital dietary element, which regulates a number of physiological processes in central nervous system. The present study was conducted to explore the protective potential of zinc, if any, in ameliorating neurotoxicity induced by aluminium. Male Sprague Dawley rats received either aluminium chloride (AlCl3) orally (100 mg kg(-1) b.wt. per day), zinc sulphate (ZnSO4) at a dose level of 227 mg L(-1) in drinking water or combined treatment of aluminium and zinc for 8 weeks. Aluminium treatment significantly elevated the levels of lipid peroxidation and reactive oxygen species as well as the activities of catalase, superoxide dismutase and glutathione reductase, which however were decreased following Zn co-treatment of Al-treated rats. In contrast, Al treatment decreased the activities of glutathione-S-transferase as well as the levels of reduced glutathione, oxidised glutathione and total glutathione, but co-administration of Zn to Al-treated animals increased these levels. Furthermore, Al treatment caused a significant increase in the levels of Fe and Mn as well as of Al but decreased the Zn and metallothionein levels. In the Zn-supplemented animals, the levels of Al, Fe, Mn were found to be significantly decreased, whereas the levels of metallothionein as well as Zn were increased. Moreover, histopathological alterations such as vacuolization and loss of Purkinje cells were also evident following Al treatment, which showed improvement upon Zn supplementation. Therefore, zinc has the potential to alleviate aluminium-induced neurodegeneration.

Flaxseed oil as a neuroprotective agent on lead acetate-induced monoamineric alterations and neurotoxicity in rats

Lead remains a considerable occupational and public health problem, which is known to cause a number of adverse effects in both man and animals. Here, the neuroprotective effect of flaxseed oil (1,000 mg/kg) on lead acetate (20 mg/kg) induced alternation in monoamines and brain oxidative stress was examined in rats. The levels of lead, dopamine (DA), norepinephrine (NE), serotonin (5-HT), lipid peroxidation, nitrite/nitrate (NO), and glutathione (GSH) were determined; also, the activity of acetylcholinesterase (AChE) and Na(+)-K(+)-ATPase were estimated on different brain regions of adult male albino rats. The level of lead was markedly elevated in different brain regions of rats. This leads to enhancement of lipid peroxidation and NO production in brain with concomitant reduction in AChE activity and GSH level. In addition, the levels of DA, NE, and 5-HT were decreased in the brain. These findings were associated with BAX over expression. Treatment of rats with flaxseed oil induced a marked improvement in most of the studied parameters as well as the immunohistochemistry features. These data indicated that dietary flaxseed oil provide protection against lead-induced oxidative stress and neurotoxic effects.

Perinatal lead exposure alters postnatal cholinergic and aminergic system in rat brain: reversal effect of calcium co-administration

Our earlier studies indicated the role of neurotransmitter systems in lead (Pb) induced behavioral perturbations. In this study, we examined the alterations in synaptosomal acetylcholine (ACh), epinephrine, dopamine, acetylcholinesterase (AChE), and mitochondrial monoamine oxidase (MAO) in the cerebellum and hippocampus of perinatally Pb-exposed rats. Rats (Wistar) were exposed to 0.2% Pb (Pb acetate in drinking water of mother) from gestational day 6 and the pups were exposed lactationally (through mother's milk) to Pb till weaning (postnatal day 21). Studies conducted on different postnatal days (PND 21, 28, 35 and 60) showed significant decreases in synaptosomal AChE and mitochondrial MAO activities, and increases in the levels of ACh, dopamine and epinephrine in the cerebellum and hippocampus of Pb-exposed rats. These alterations were greater at PND 35 and more pronounced in the cholinergic system (ACh and AChE) of hippocampus and the aminergic system (epinephrine, dopamine and MAO) of cerebellum. The total locomotor activity and exploratory behavior were also decreased significantly in Pb-exposed animals corresponding to the alterations observed in cholinergic and aminergic systems. Calcium administration together with Pb, however significantly reversed the Pb-induced alterations in transmitters and enzymes, as well as exploratory and motor behavior suggesting protective effect of calcium in Pb-exposed animals.

Effects of flaxseed oil on lead acetate-induced neurotoxicity in rats

It is well known that chronic exposure to lead (Pb(+2)) alters a variety of behavioral tasks in rats and mice. Here, we investigated the effect of flaxseed oil (1,000 mg/kg) on lead acetate (20 mg/kg)-induced brain oxidative stress and neurotoxicity in rats. The levels of Pb(+2), lipid peroxidation, nitric oxide (NO), and reduced glutathione (GSH) and the activity of catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione-S-transferase (GST), and glutathione peroxidase (GPx) were determined in adult male albino rats. The level of Pb(+2) was markedly elevated in brain and blood of rats. This leads to enhancement of lipid peroxidation and NO production in brain with concomitant reduction in GSH, CAT, SOD, GR, GST, and GPx activities. These findings were associated with DNA fragmentation. In addition, lead acetate induced brain injury as indicated by histopathological changes of the brain. Treatment of rats with flaxseed oil resulted in marked improvement in most of the studied parameters as well as histopathological features. These findings suggest to the conclusion that flaxseed oil significantly decreased the adverse harmful effects of lead acetate exposure on the brain as well as Pb(+2)-induced oxidative stress.

Calcium and zinc supplementation protects lead (Pb)-induced perturbations in antioxidant enzymes and lipid peroxidation in developing mouse brain

Several studies have implicated oxidative stress as one of the important mechanisms of toxic effects of lead (Pb). In the present study we tested the beneficial effects of calcium (Ca2+) and zinc (Zn2+) in protecting the Pb-induced oxidative stress in the brains of developing and adult mice. Mice were lactationally exposed to 0.2% Pb and supplemented with either calcium (Ca2+) or zinc (Zn2+) and the mitochondrial antioxidant enzymes [superoxide dismutase (SOD), xanthine oxidase (XO) and catalase (CAT)] and lipid peroxidation (LP) were analyzed in cortex, hippocampus, cerebellum and medulla of brains excised on postnatal day (PND) 14, 21, 28 and 3 months. The levels of free radicals were measured using direct Electron Paramagnetic Resonance (EPR) spectroscopy. Exposure to Pb resulted a significant decrease in the activities of SOD, XO and CAT while the LP levels were significantly increased in different brain regions. Evaluation of EPR signals and g-values showed abundant accumulation of free radicals in different regions of the brain following Pb exposure. Interestingly the supplementation with Ca2+ or Zn2+ reversed the Pb-induced effects on antioxidant enzymes, LP and free radical formation; however Zn2+ supplementation appeared to be more protective. These findings strongly support that zinc and calcium supplementation significantly protect the Pb-induced oxidative stress, a major contributing factor to neurotoxicity.

Effect of short-time exposures to nickel and lead on brain monoamine oxidase from Danio rerio and Poecilia reticulata

The aim of this work was to verify, in two small size freshwater teleosts Danio rerio and Poecilia reticulata, the effects of short-time exposures (24 and 72 h) to a sublethal dose (500 microg/L) of nickel and lead, on brain monoamine oxidase (MAO), an important neural enzyme. The 24-h treatment using both metals caused a strong reduction of MAO activity in D. rerio brain, whereas causing a slight MAO activity stimulation in P. reticulata brain. The same treatment in both species did not affect the brain MAO mRNA production as showed by RT-PCR. Extending the duration of treatment as far as 72 h, partly (D. rerio) or completely (P. reticulata) reversed the metal effects on brain MAO activity suggesting that mechanisms to neutralize the metals had been activated.

Chronic low-level lead exposure affects the monoaminergic system in the mouse superior olivary complex

Low-level lead (Pb) exposure is associated with behavioral and cognitive dysfunction, but it is not clear how Pb produces these behavioral changes. Pb has been shown to alter auditory temporal processing in both humans and animals. Auditory temporal processing occurs in the superior olivary complex (SOC) in the brainstem, where it is an important component in sound detection in noisy environments and in selective auditory attention. The SOC receives a serotonergic innervation from the dorsal raphe, and serotonin has been implicated in auditory temporal processing within the brainstem and inferior colliculus. Because Pb exposure modulates auditory temporal processing, the serotonergic system is a potential target for Pb. The current study was undertaken to determine whether developmental Pb exposure preferentially changes the serotonergic system within the SOC. Pb-treated mice were exposed to no Pb, very low Pb (0.01 mM), or low Pb (0.1 mM) throughout gestation and through 21 days postnatally. Brainstem sections from control and Pb-exposed mice were immunostained for the vesicular monoamine transporter 2 (VMAT2), serotonin (5-HT), and dopamine-beta-hydroxylase (DbetaH; a marker for norepinephrine) in order to elucidate the effect of Pb on monoaminergic input into the SOC. Sections were also immunolabeled with antibodies to vesicular glutamate transporter 1 (VGLUT1), vesicular gamma-aminobutyric acid (GABA) transporter (VGAT), and vesicular acetylcholine transporter (VAChT) to determine whether Pb exposure alters the glutaminergic, GABAergic, or cholinergic systems. Pb exposure caused a significant decrease in VMAT2, 5-HT, and DbetaH expression, whereas VGLUT1, VGAT, and VAChT showed no change. These results provide evidence that Pb exposure during development alters normal monoaminergic expression in the auditory brainstem.