Effects of antimony on antioxidant system, damage indexes of blood-brain barrier and ultrastructure of zebrafish (Danio rerio)

Antimony (Sb) and its compounds can be harmful to people and are known to cause cancer, so they are a key pollutant to control. This study investigated the influence of antimony on non-enzymatic antioxidants and the blood-brain barrier (BBB) in zebrafish(Danio rerio), a model organism that shares a high degree of genetic similarity with humans. Zebrafish were exposed to different doses of antimony in water for 7, 18, and 30 days. The results indicated that antimony accumulated most in the liver, followed by the gills, flesh, and brain, with the accumulation increasing as the exposure duration extends. Additionally, under identical antimony concentrations, the buildup in the four tissues was positively correlated with the duration of exposure. After 18 days of exposure, the total antioxidant capacity (T-AOC) and endogenous non-enzymatic antioxidants vitamin C (VC) and vitamin E (VE) decreased as a result of antimony ingestion in zebrafish, although cysteine secretion was increased in the liver, gills, and brain. The structural integrity of the BBB was compromised by the elevation of ApoE4 and MMP-9 levels as a result of antimony exposure, which led to the breakdown of the basal lamina, tight junctions, and nerve fibers in the brain. At this injured region, 5-HT and MBP were also able to easily enter and leave the BBB, albeit at variable rates. Additionally, when the antimony exposure level reached 16.58 mg·L-1, antimony penetrated the BBB and bound to erythrocytes, causing their lysis.

Prenatal exposure to metal mixtures and childhood temporal processing in the PROGRESS Birth Cohort Study: Modification by childhood obesity

Children are frequently exposed to various biological trace metals, some essential for their development, while others can be potent neurotoxicants. Furthermore, the inflammatory and metabolic conditions associated with obesity may interact with and amplify the impact of metal exposure on neurodevelopment. However, few studies have assessed the potential modification effect of body mass index (BMI). As a result, we investigated the role of child BMI phenotype on the relationship between prenatal exposure to metal mixtures and temporal processing. Leveraging the PROGRESS birth cohort in Mexico City, children (N = 563) aged 6-9 years completed a Temporal Response Differentiation (TRD) task where they had to hold a lever down for 10-14 s. Blood and urinary metal (As, Pb, Cd, and Mn) measurements were collected from mothers in the 2nd and 3rd trimesters. Child BMI z-scores were dichotomized to normal (between -2 and +0.99) and high (≥1.00). Covariate-adjusted weighted quantile sum (WQS) regression models were used to estimate and examine the combined effect of metal biomarkers (i.e., blood and urine) on TRD measures. Effect modification by the child's BMI was evaluated using 2-way interaction terms. Children with a high BMI and greater exposure to the metal mixture during prenatal development exhibited significant temporal processing deficits compared to children with a normal BMI. Notably, children with increased exposure to the metal mixture and higher BMI had a decrease in the percent of tasks completed (β = -10.13; 95 % CI: -19.84, -0.42), number of average holds (β = -2.15; 95 % CI: -3.88, -0.41), longer latency (β = 0.78; 95 % CI: 0.13, 1.44), and greater variability in the standard deviation of the total hold time (β = 2.08; 95 % CI: 0.34, 3.82) compared to normal BMI children. These findings implicate that high BMI may amplify the effect of metals on children's temporal processing. Understanding the relationship between metal exposures, temporal processing, and childhood obesity can provide valuable insights for developing targeted environmental interventions.

Deciphering the role of metal and non-metals in the treatment of epilepsy

Metals and non-metals have known to play a significant role in various physiological roles in the body including the central nervous system (CNS). The alterations in their concentration in the CNS leads to abnormalities in the normal functions which may lead to various neurological conditions including epilepsy. Manganese is a cofactor required for antioxidant enzymes such as Superoxide dismutase, Glutamine synthetase, etc. The accumulation of iron leads to formation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) which have the potential to cause ferroptosis, one of the reasons for epileptogenesis. Zinc has biphasic response, both neurotoxic and neuroprotective, based on concentration levels in the CNS. Selenium is a main element for selenoproteins which is responsible for the regulation of oxidative state and antioxidant defence mechanism. The reduction in the phosphorous levels in the CNS is widely observed after generalised tonic clonic seizures (GTC), which can be a potential diagnostic biomarker. Copper acts in the CNS in an identical manner, i.e., by blocking both AMPA mediated and GABA mediated neuronal transmission. Magnesium blocks calcium channels in the NMDA receptor and prevents glutamatergic transmission, thus inhibiting excitotoxicity. Lithium acts as a proconvulsive agent and is used in combination with pilocarpine to induce seizures. The identified potential of metals and non-metals in epilepsy can be utilised in order to devise new adjuvant therapies for the management of epilepsy. The article summaries in depth the role of metals and non-metals in the treatment of epilepsy supported with special paragraph on author perspective on to the topic. Furthermore, an update of preclinical and clinical evidences are discussed in the review to give evidence on metal and non-metal based therapies in epilepsy.

Coal mine effluent-induced metal bioaccumulation, biochemical, oxidative stress, metallothionein, and histopathological alterations in vital tissues of the catfish, Clarias batrachus

In the present study, a multi-biomarker approach was used to assess the toxicity of the coal mine effluent (CME) generated at the Rajrappa coal mine on the catfish Clarias batrachus. A core of biomarkers indicative of nutritional value, oxidative stress, and histopathology was selected to illustrate the toxic effects of CME-containing different heavy metals and other toxicants. The results of metal bioaccumulation in CME-exposed fish tissues revealed the highest metal concentration in liver (1.34-297.68 mg/kg) while lowest in muscles (1.47-23.26 mg/kg) as compared to other tissues and so was the metallothionein level. The high value of bioaccumulation observed in liver, kidney, and gills reflects their affinity for metals. In addition, the values of metal pollution index (MPI) of different fish tissues further affirmed that liver followed by kidney and gills are at greater risk than brain, skin, and muscles. Significant alterations in the activity of certain enzymes (aspartate amino transferase, alanine amino transferase, alkaline phosphatase) as well as oxidative stress markers (superoxide dismutase, catalase and lipid peroxidation) were detected in the tissues of CME-exposed fish. The tissue-specific metal accumulation and increased metallothionein levels may be associated with the biochemical and physiological activity of an organ and its constitutive antioxidant defenses. The histopathological changes in the various tissues of the CME-exposed fish justify the high metal accumulation and biochemical alterations. Overall results indicate that the Rajrappa coal mine effluent is very toxic having adverse health impact on the fish and might also affect the human health when consumed.

Zinc supplementation affects favorably the frequency of migraine attacks: a double-blind randomized placebo-controlled clinical trial

BACKGROUND

Observational studies have shown a link between zinc deficiency and migraine headaches. We aimed to examine the effect of zinc supplementation on the characteristics of migraine attacks in patients with migraine.

METHODS

This randomized clinical trial was conducted on 80 patients with migraine. Patients were randomly assigned to receive either zinc sulfate (220 mg/d zinc sulfate) or placebo (lactose) for 8 weeks. Anthropometric measures, serum zinc concentrations, and characteristics of migraine attacks (headache severity, frequency and duration of migraine attacks, and headache daily results) were assessed at baseline and end of the trial.

RESULTS

Compared with the placebo, zinc supplementation resulted in a significant reduction in headache severity (- 1.75 ± 1.79 vs. -0.80 ± 1.57; P = 0.01) and migraine attacks frequency (- 2.55 ± 4.32 vs. -0.42 ± 4.24; P = 0.02) in migraine patients. However, the observed reduction for headache severity became statistically non-significant when the analysis was adjusted for potential confounders and baseline values of headache severity. Other characteristics of migraine attacks including the duration of attacks and headache daily results were not altered following zinc supplementation either before or after controlling for covariates.

CONCLUSION

Zinc supplementation had a beneficial effect on the frequency of migraine attacks in migraine patients. Additional well-designed clinical trials with a long period of intervention and different dosages of zinc are required.

TRIAL REGISTRATION CODE

IRCT20121216011763N23 at www.irct.ir .

Long-term administration of excess zinc impairs learning and memory in aged mice

Zinc (Zn) is an essential element, but excess amounts are known to cause neurotoxic effects. The risk of excessive Zn intake is increased by supplementing food intake with dietary supplements. Ageing affects many cellular processes that predispose individuals to neurodegeneration. Indeed, the prevalence of senile dementia such as Alzheimer's disease, Parkinson's disease, and vascular-type dementia increases with age. As such, we investigated the effects of long-term exposure to excess Zn on learning and memory in aged mice. ICR-JCL female mice (aged 26 weeks) were administered 0, 200, or 500 ppm Zn as zinc chloride in drinking water for 30 weeks. After 30-week administration, aged female animals were subjected to Y-maze, novel object recognition, and step-through passive avoidance tests. Chronic exposure to Zn did not inhibit learning and memory in the Y-maze test, but dose-dependently inhibited learning and memory in novel object recognition and step-through passive avoidance tests. These results indicate the potential for chronic Zn exposure to dose-dependently inhibit both long-term and novel object recognition memory. Results of microarray analysis revealed significant changes in gene expression of transthyretin and many olfactory receptors in the hippocampus of Zn-treated mice.

Coal mine effluent-led bioaccumulation of heavy metals and histopathological changes in some tissues of the catfish Clarias batrachus

Coal mining generates huge quantity of toxic effluent which consistently pollutes the neighboring wetlands where the local inhabitants regularly cultivate edible fishes. In the present study the concentration of heavy metals Fe, Zn, Cu, Mn, Ni, Cd, Pb and Cr were analyzed in the water and various tissues of edible catfish Clarias batrachus reared in a pond receiving effluents from Rajrappa coal mine, Jharkhand, India. The metal concentrations in the pond water were dramatically higher (Fe 350%, Zn 423%, Cu 12%, Mn 7029%, Ni 713%, Cd 1700%, Pb 4333% and Cr 588%) than the safe limit of Environmental Pollution Agency (2003) as well as the control tap water. Excessive amounts of metals in effluent caused their substantial transfer to the different tissues of the catfish reared in such ponds. Results showed that accumulation of metals in fish tissues were in the following order: liver > kidney > air breathing organ (ABO) > gills > skin > brain > muscles. Among the various tissues the highest accumulation of most of the metals was recorded in the liver (2.05-271.28 mg/kg dry weight) and lowest in the muscles (1.39-30.27 mg/kg dry weight), while the concentration of metals in other tissues ranged in between. The accumulation of heavy metals in tissues appears to cause remarkable histopathological alterations in skin, gills, ABO, liver and kidney that might be leading to deleterious effect on fish physiology and consequently impact the consumers of such fishes.

Contamination of metals in different tissues of rohu (Labeo rohita, Cyprinidae) collected from the Indian River Ganga

In the present paper, accumulation of zinc (Zn), iron (Fe), copper (Cu), chromium (Cr), nickel (Ni), manganese (Mn) and lead (Pb) was determined in different tissues (skin, muscles, liver, gills, kidney and brain) of rohu (Labeo rohita) collected from the River Ganga in Varanasi, India. Concentrations of Cu (except gills), Fe and Cr (except brain for Cr) in most of the tissues were above the permissible safe limits for human consumption suggested by the Food and Agricultural Organization (FAO 1983). Concentrations of all metals were higher in River Ganga fish than those from the University fish farm. With the exception of Zn in skin, muscle and brain tissue, the studied metals were bioaccumulated in all tissues. The total metal accumulation or metal pollution index was highest in liver (20.8 ± 0.50) followed by kidney (16.8 ± 0.44), gills (15.2 ± 0.15), muscles (12.1 ± 0.08), skin (10.5 ± 0.53) and brain (7.0 ± 0.02).

Three-dimensional atlas of iron, copper, and zinc in the mouse cerebrum and brainstem

Atlases depicting molecular and functional features of the brain are becoming an integral part of modern neuroscience. In this study we used laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS) to quantitatively measure iron (Fe), copper (Cu), and zinc (Zn) levels in a serially sectioned C57BL/6 mouse brain (cerebrum and brainstem). Forty-six sections were analyzed in a single experiment of approximately 158 h in duration. We constructed a 46-plate reference atlas by aligning quantified images of metal distribution with corresponding coronal sections from the Allen Mouse Brain Reference Atlas. The 46 plates were also used to construct three-dimensional models of Fe, Cu, and Zn distribution. This atlas represents the first reconstruction of quantitative trace metal distribution through the brain by LA-ICPMS and will facilitate the study of trace metals in the brain and help to elucidate their role in neurobiology.

Manganese and epilepsy: a systematic review of the literature

Manganese is an essential trace element for the development and function of the central nervous system. Alterations in manganese concentrations, whether excessive or deficient, can be accompanied by convulsions. This article represents a systematic review of available quantitative evidence that might clarify this issue. We searched The Cochrane Library, Medline and LILACS databases from January 1966 through June 2006 and reviewed all resulting English and Spanish language publications, as well as those possibly relevant in other languages based on their abstracts. The final selection included for this review comprises all investigations in humans and animals that compared manganese levels in any tissue of a group with spontaneous or induced convulsions (with or without antiepileptic treatment) and a convulsion-free control group. The literature search identified thirteen publications since then relevant to the issue, four of which failed to meet our criteria for inclusion. Of the remaining nine, six were in humans and three in rodents. At present, there is no satisfactory explanation for the relationship between low manganese levels and the presence of convulsions. There is a documented correlation between low blood manganese levels and the presence of convulsions in both humans and animals. The lack of evidence indicating whether this is a cause or an effect of the convulsions clearly justifies more detailed follow-up investigations in humans.

Analysis of size characterized manganese species from liver extracts using capillary zone electrophoresis coupled to inductively coupled plasma mass spectrometry (CZE-ICP-MS)

Mn is of toxicological concern because overexposure can lead to progressive, permanent neurodegenerative damage. Monomethyl-Mn-pentadienyl-tricarbonyl (MMT) is used as an anti-knock agent in fuel. Exhausted Mn compounds are absorbed in the lung and transported to the liver. Extended exposure causes an overflow of the liver with Mn species moving e.g. to the brain, causing irreversible central nervous system (CNS) disorders like Manganism. This paper focuses on experiments for getting more information on Mn species in liver extracts. The investigations are performed with respect to (1) a size characterization and (2) a subsequent identification of the Mn species in liver extracts using preparative size exclusion chromatography (SEC) followed by capillary zone electrophoresis coupled to inductively coupled plasma mass spectrometry (CZE-ICP-MS). First, extracts were analyzed using a mass calibrated SEC column coupled to ICP-MS detection. The chromatogram showed the 55 Mn-trace and proved main Mn elution between ca. 60-150 kDa. Second, liver extracts were fractionated on the same SEC column, however, now the effluent was directed to a fraction collector. This resulted in fractions containing pre-purified, size characterized Mn species per fraction. It turned out that the Mn concentrations per fraction reflected roughly the previous on-line Mn trace. Third, the fractions were subject to CZE-ICP-MS, where the MS was operated additionally with dynamic reaction cell (DRC) technique. From size characterization (with SEC coupled on-line to ICP-MS or connected to a fraction collector and subsequent Mn determination in fractions) it was shown that most Mn species from liver extract were of high molecular mass (HMM) nature as they eluted mostly between 50 and 80 min, corresponding to ca. 60-150 kDa. With the two-dimensional speciation approach employing first SEC and then CZE-ICP-DRC-MS together with standard addition method, a series of Mn species was identified. Mn species predominantly were Mn-enzymes e.g. arginase, isocitric dehydrogenase, galactosyltransferase, prolidase, pyruvate carboxylase and oxalate oxidase. A typical Mn-transporter--Mn-albumin-- was also seen, whilst Mn-transferrin obviously was degraded during SEC separation. This Mn-compound (independent whether as a standard or from liver extract) was not stable during SEC even at the finally chosen physiological conditions.