Altered uptake and biological half-lives of 65Zn on arsenic exposure--modulation by zinc treatment

Influence of Dietary Compounds on Arsenic Metabolism and Toxicity. Part I-Animal Model Studies

Population and laboratory studies indicate that exposure to various forms of arsenic (As) is associated with many adverse health effects; therefore, methods are being sought out to reduce them. Numerous studies focus on the effects of nutrients on inorganic As (iAs) metabolism and toxicity, mainly in animal models. Therefore, the aim of this review was to analyze the influence of methionine, betaine, choline, folic acid, vitamin B₂, B₆, B₁₂ and zinc on the efficiency of iAs metabolism and the reduction of the severity of the whole spectrum of disorders related to iAs exposure. In this review, which includes 58 (in vivo and in vitro studies) original papers, we present the current knowledge in the area. In vitro and in vivo animal studies showed that methionine, choline, folic acid, vitamin B₂, B₁₂ and zinc reduced the adverse effects of exposure to iAs in the gastrointestinal, urinary, lymphatic, circulatory, nervous, and reproductive systems. On the other hand, it was observed that these compounds (methionine, choline, folic acid, vitamin B₂, B₁₂ and zinc) may increase iAs metabolism and reduce toxicity, whereas their deficiency or excess may impair iAs metabolism and increase iAs toxicity. Promising results of in vivo and in vitro on animal model studies show the possibility of using these nutrients in populations particularly exposed to As.

Zinc treatment modulates hematological and morphological changes in rat erythrocytes following arsenic exposure

The aim of this study was to understand the effects of zinc supplementation on antioxidant defense systems, hematological indices, and erythrocyte morphology in conditions of chronic arsenic toxicity. Male Wistar rats were segregated into four groups: control, arsenic treated, zinc supplemented, and arsenic + zinc treated. The animals in the arsenic-treated group were given arsenic orally in drinking water in the form of sodium arsenite at a dose level of 100 mg L^-1, and zinc was administered to zinc-treated animals in the form of zinc sulfate orally in drinking water at a dose level of 227 mg L^-1. The animals were subjected to different treatments for a period of 12 weeks, and various investigations were undertaken that included serum zinc content, activity of antioxidant enzymes, and hematological indices. Further, scanning electron microscopic (SEM) studies were performed to assess morphological changes in erythrocytes. Arsenic treatment significantly reduced serum zinc concentrations, which, however, were restored to near-normal levels upon zinc supplementation. The activities of enzymes involved in antioxidant defense systems were altered in the erythrocyte lysates of arsenic-treated rats, which interestingly revealed a significant improvement upon simultaneous zinc supplementation. A significant reduction in the counts of total leukocytes, neutrophils, and lymphocytes was observed following arsenic intoxication, which came back to near control levels following zinc supplementation. Also, protective effects of zinc were evident from SEM that revealed maintenance of topographical appearances of erythrocytes in conditions of arsenic toxicity. Thus, this study clearly shows the protection afforded by zinc on erythrocytes during arsenic-induced toxicity.

Hepatoprotective effects of zinc (II) via cytochrome P-450/reactive oxygen species and canonical apoptosis pathways after arsenite waterborne exposure in common carp

Chronic arsenicosis has threatened the survival of aquatic animals with molecular mechanisms yet clear. In the present study, liver damage was evident by fluctuated activities of transaminases and declined ATPases in common carp under arsenic (As) exposure for 30 days. Mechanically, As significantly decreased cytochrome P-1A (CYP1A) activity and increased reactive oxygen species (ROS) content, which corroborated mitochondrial dysfunction in the hepatocytes. This hypothesis was further suggested by Caspase-3-executed apoptosis by death receptor pathway (Fas, TNF-α and Caspase-8) and mitochondrial pathway (Bax, Bcl-2 and Caspase-9). The above results indicated that As-elicited oxidative damage lead to apoptotic hepatic injury in carp. On the contrary, zinc (Zn) exerted an ROS scavenger and an antidote to As in the present model evidenced by alleviated liver injury and restored liver function index. Moreover, Zn and As co-administration displayed partially recovered CYPs enzyme system and quenched apoptotic positive cells compared As treated alone. These outcomes could be applied to develop counter practices based on Zn preparations to decrease the biotoxicity of As.

Selenium and zinc protections against metal-(loids)-induced toxicity and disease manifestations: A review

Metals are ubiquitous in the environment due to huge industrial applications in the form of different chemicals and from extensive mining activities. The frequent exposures to metals and metalloids are crucial for the human health. Trace metals are beneficial for health whereas non-essential metals are dangerous for the health and some are proven etiological factors for diseases including cancers and neurological disorders. The interactions of essential trace metals such as selenium (Se) and zinc (Zn) with non-essential metals viz. lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) in biological system are very critical and complex. A huge number of studies report the protective role of Se and Zn against metal toxicity, both in animal and cellular levels, and also explain the numerous mechanisms involved. However, it has been considered that a tiny dyshomeostasis in the metals/trace metals status in biological system could induce severe deleterious effects that can manifest to numerous diseases. Thus, in this particular review, we have demonstrated the critical protection mechanism/s of Se and Zn against Cd, Pb, As and Hg toxicity in a one by one manner to clarify the up-to-date findings and perspectives. Furthermore, biomolecular consequences are comprehensively presented in light of particular cellular/biomolecular events which are somehow linked to a subsequent disease. The analyzed reports support significant protection potential of Se and Zn, either alone or in combination with other agents, against each of the abovementioned non-essential metals. However, Se and Zn are still not being used as detoxifying agents due to some unexplained reasons. We hypothesized that Se could be a potential candidate for detoxifying As and Hg regardless of their chemical speciations, but requires intensive clinical trials. However, particularly Zn-Hg interaction warrants more investigations both in animal and cellular level.

Assessment of 28 trace elements and 17 amino acid levels in muscular tissues of broiler chicken (Gallus gallus) suffering from arsenic trioxide

The contents of 28 trace elements, 17 amino acid were evaluated in muscular tissues (wings, crureus and pectoralis) of chickens in response to arsenic trioxide (As₂O₃). A total of 200 one-day-old male Hy-line chickens were fed either a commercial diet (C-group) or an As₂O₃ supplement diet containing 7.5mg/kg (L-group), 15mg/kg (M-group) or 30mg/kg (H-group) As₂O₃ for 90 days. The elements content was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Under As₂O₃ exposure, the concentration of As were elevated 8.87-15.76 fold, 7.93-15.63 fold and 5.94-12.45 fold in wings, crureus and pectoralis compared to the corresponding C-group, respectively. 19 element levels (lithium (Li), magnesium (Mg), aluminum (Al), silicon (Si), kalium (K), vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), selenium (Se), strontium (Sr), molybdenum (Mo), cadmium (Cd), tin (Sn), antimony (Sb), barium (Ba), mercury (Hg) and lead (Pb), 9 element levels (K, Co, Ni, Cu, As, Se, Sr, Sn, Ba and Hg) and 4 element levels (Mn, cobalt (Co), As, Sr and Ba) were significantly increased (P < 0.05) in wing, crureus and pectoralis, respectively. 2 element levels (sodium (Na) and zinc (Zn)), 5 element levels (Li, Na, Si, titanium (Ti and Cr), 13 element levels (Li, Na, Mg, K, V, Cr, iron (Fe), Cu, Zn, Mo, Sn, Hg and Pb) were significantly decreased (P < 0.05) in wing muscle, crureus and pectoralis, respectively. Additionally, in crureus and pectoralis, the content of total amino acids (TAA) was no significant alterations in L and M-group and then increased approximately 10.2% and 7.6% in H-group, respectively (P < 0.05). In wings, the level of total amino acids increased approximately 10% in L-group, whereas it showed unchanged in M and H-group compared to the corresponding C-group. We also observed that significantly increased levels of proline, cysteine, aspartic acid, methionine along with decrease in the tyrosine levels in muscular tissues compared to the corresponding C-group. In conclusion, the residual of As in the muscular tissues of chickens were dose-dependent and disrupts trace element homeostasis, amino acids level in muscular tissues of chickens under As₂O₃ exposure. Additionally, the response (trace elements and amino acids) were different in wing, thigh and pectoral of chick under As₂O₃ exposure. This study provided references for further study of heavy metal poisoning and may be helpful to understanding the toxicological mechanism of As₂O₃ exposure in muscular tissues of chickens.

Effect of vitamin E supplementation on arsenic induced alteration in blood biochemical profile, oxidant/antioxidant status, serum cortisol level and retention of arsenic and selenium in goats

Arsenic (As) exerts oxidative stress with depletion of body selenium in monogastric animals. But in ruminants this fact is not yet verified. Vitamin E is an effective dietary antioxidant. Thus, in this experiment, the protective effect of vitamin E against arsenic toxicity induced by sodium arsenite (60mg As/kg diet) was investigated in goat kids. For this, 21 male kids were divided into three equal groups and fed either basal diet as such (control), or supplemented with 60mg As/kg diet and 60mg As/kg diet+250IU vitamin E/kg diet for 180 days. Vitamin E supplementation alleviated the toxic effects caused by arsenic on serum alanine aminotransferase and aspartate aminotransferase and lipid peroxidation. It also prevented the depletion of reduced glutathione content and reduction in activity of catalase, superoxide dismutase and glutathione-s-transferase in erythrocytes resulted from arsenic intoxication. The elevated levels of arsenic and reduced levels of selenium in the serum and tissues in arsenic treated animals were attenuated by vitamin E supplementation, though not completely. However, serum cortisol level was not affected by arsenic. It was concluded that arsenic exerts cortisol independent stressor mechanism and supplementation of vitamin E at a level of 250IU/kg diet was partially effective in reducing tissue accumulation of arsenic in the body and protect the kids from oxidative stress induced by arsenic.

Blood biochemistry, thyroid hormones, and oxidant/antioxidant status of guinea pigs challenged with sodium arsenite or arsenic trioxide

The present experiment aimed to compare the two most commonly used compounds of arsenic (sodium arsenite and arsenic trioxide) for their effect on blood metabolites, thyroid hormones, and oxidant/antioxidant status in guinea pigs. Twenty-one adult guinea pigs were randomly divided into three equal groups. Animals in group T1 (control) were fed a basal diet, whereas 50 ppm arsenic was added in the basal diet either as sodium arsenite (T2) or arsenic trioxide (T3) and fed for 11 weeks. Serum aspartate aminotransferase and alanine aminotransferase activities were significantly increased along with a decrease in blood hemoglobin level in both the arsenic-administered groups. The level of erythrocytic antioxidants (catalase, superoxide dismutase, reduced glutathione, glutathione-S-transferase, and glutathione reductase) was decreased and lipid peroxidation was elevated upon arsenic exposure. Serum thyroid hormone levels were reduced and arsenic levels in tissues increased in both the arsenic-exposed groups, irrespective of the arsenic compound. Thus, sodium arsenite and arsenic trioxide exerted similar adverse effects on blood metabolic profile, antioxidant status, and thyroid hormones in guinea pigs.