Effects of oral exposure to arsenite on arsenic metabolism and transport in rat kidney.

Nephrotoxicity is within the recognized toxic effects of arsenic. In this study we assessed the effect of arsenite on the renal capacity to metabolize and handle arsenicals in rats exposed to drinking water with 0, 1, 5, or 10 ppm sodium arsenite for ten days. Arsenite treatment did not affect the gene expression of the main enzyme catalyzing methylation of arsenite, As3mt, while it reduced the expression of GSTO1 mRNA and protein. Arsenite decreased the expression of Aqp3, Mrp1, Mrp4, and Mdr1b (i.e., transporters and channels used by arsenic), but not that of Aqp7, Glut1, Mrp2, and Mdr1a. The protein abundance of AQP3 was also reduced by arsenite. Arsenite increased urinary NGAL and FABP3 and decreased Klotho plasma levels, without alteration of creatinine, which evidenced early tubular damage. Renal Klotho mRNA and protein expressions were also downregulated, which may exacerbate renal damage. No effect was observed in selected miRNAs putatively associated with renal injury. Plasma PTH and FGF23 were similar between groups, but arsenite decreased the renal expression of Fgfr1 mRNA. In conclusion, exposure to arsenite alters the gene expression of proteins involved in the cellular handling of arsenical species and elicits tubular damage.

Human red blood cell uptake and sequestration of arsenite and selenite: Evidence of seleno-bis(S-glutathionyl) arsinium ion formation in human cells.

Over 200 million people worldwide are exposed to the human carcinogen, arsenic, in contaminated drinking water. In laboratory animals, arsenic and the essential trace element, selenium, can undergo mutual detoxification through the formation of the seleno-bis(S-glutathionyl) arsinium ion [(GS)2AsSe]-, which undergoes biliary and fecal elimination. [(GS)2AsSe]-, formed in animal red blood cells (RBCs), sequesters arsenic and selenium, and slows the distribution of both compounds to peripheral tissues susceptible to toxic effects. In human RBCs, the influence of arsenic on selenium accumulation, and vice versa, is largely unknown. The study aims were to characterize arsenite (AsIII) and selenite (SeIV) uptake by human RBCs, to determine if SeIV and AsIII increase the respective accumulation of the other in human RBCs, and ultimately to determine if this occurs through the formation and sequestration of [(GS)2AsSe]-. 75SeIV accumulation was temperature and Cl--dependent, inhibited by 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonic acid (H2DIDS) (IC50 1 ± 0.2 µM), and approached saturation at 30 µM, suggesting uptake is mediated by the erythrocyte anion-exchanger 1 (AE1 or Band 3, gene SLC4A1). HEK293 cells overexpressing AE1 showed concentration-dependent 75SeIV uptake. 73AsIII uptake by human RBCs was temperature-dependent, partly reduced by aquaglyceroporin 3 inhibitors, and not saturated. AsIII increased 75SeIV accumulation (in the presence of albumin) and SeIV increased 73AsIII accumulation in human RBCs. Near-edge X-ray absorption spectroscopy revealed the formation of [(GS)2AsSe]- in human RBCs exposed to both AsIII and SeIV. The sequestration of [(GS)2AsSe]- in human RBCs potentially slows arsenic distribution to susceptible tissues and could reduce arsenic-induced disease.

Pharmacokinetic Properties of Arsenic Species after Intravenous and Intragastrical Administration of Arsenic Trioxide Solution in Cynomolgus Macaques Using HPLC-ICP-MS.

A rapid and sensitive method was established for arsenic (As) speciation based on high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). This method was validated for the quantification of four arsenic species, including arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV) in cynomolgus macaque plasma. Separation was achieved in just 3.7 min with an alkyl reverse phase column and highly aqueous mobile phase containing 20 mM citric acid and 5 mM sodium hexanesulfonate (pH = 4.3). The calibration curves were linear over the range of 5⁻500 ng·mL-1 (measured as As), with r > 0.99. The above method was validated for selectivity, precision, accuracy, matrix effect, recovery, carryover effect and stability, and applied in a comparative pharmacokinetic study of arsenic species in cynomolgus macaque samples following intravenous and intragastrical administration of arsenic trioxide solution (0.80 mg·kg-1; 0.61 mg·kg-1 of arsenic); in addition, the absolute oral bioavailability of the active ingredient AsIII of arsenic trioxide in cynomolgus macaque samples was derived as 60.9 ± 16.1%.

Sodium arsenite exposure impairs B cell proliferation and enhances vascular inflammation in Plasmodium berghei mouse model.

Arsenic exposure has been linked to an impaired immune response and inflammation. Our study investigated the effects of sodium arsenite on host immune response and vascular inflammation during malarial infection. Mice were divided into three groups: control (C), Plasmodium berghei infection (I) and sodium arsenite exposure with Plasmodium berghei infection (As-I). The results showed that splenocyte proliferation stimulated by lipopolysaccharide (LPS) and pokeweed mitogen (PWM) was suppressed in the I group, and the suppression was more pronounced in the As-I group, suggesting that acquired immunity in infected mice was worsening following arsenic exposure. ICAM-1, an adhesion protein involved in parasite-infected red blood cell (iRBC) binding to endothelium, and HIF-1α, a hypoxia marker protein in the descending aorta, were increased in the As-I group compared to the I group. Collectively, our results suggest that arsenic may increase host susceptibility to malaria through suppression of B cell proliferation and enhancement of adhesion between iRBC and endothelium by increasing ICAM-1.

Individual and Combined Effects of Arsenic and Lead on Behavioral and Biochemical Changes in Mice.

Arsenic (As) toxicity has caused an environmental tragedy affecting millions of people in the world. Little is known about the toxic effects of As on neurobehavioral and biochemical changes in vivo. Along this line of metal toxicity, co-exposure of lead (Pb) could aggravate the situation in the host. The present study was designed to explore the combined effects of As and Pb on behavioral changes like anxiety, spatial memory and learning impairment, and blood indices related to organ dysfunction. Exposure of mice to As (10 mg/kg body weight), Pb (10 mg/kg body weight), and As + Pb via drinking water significantly decreased the time spent exploring the open arms while it increased the time spent in the closed arms compared to control mice in the elevated plus maze. The mean latency time of the control group to find the platform decreased significantly during the learning for 7 days compared to all three treated groups in the Morris water maze test, and the As-exposed group spent significantly less time in the desired quadrant as compared to the control group in the probe trial. Both metals posed an anxiety-like behavior and deficits in spatial memory and learning, and also altered blood indices related to liver and kidney dysfunction, and a combined exposure of these metals inhibited the individual accumulation of As and Pb. Taken together, these data suggest that As has more toxic effects on neurobehavioral and biochemical changes than Pb, and there may be antagonism in the effects and accumulation between these two toxicants.

Metabolism and toxicity of arsenicals in mammals.

Arsenic (As) is a metalloid usually found in organic and inorganic forms with different oxidation states, while inorganic form (arsenite As-III and arsenate As-v) is considered to be more hazardous as compared to organic form (methylarsonate and dimethylarsinate), with mild or no toxicity in mammals. Due to an increasing trend to using arsenicals as growth promoters or for treatment purposes, the understanding of metabolism and toxicity of As gets vital importance. Its toxicity is mainly depends on oxi-reduction states (As-III or As-v) and the level of methylation during the metabolism process. Currently, the exact metabolic pathways of As have yet to be confirmed in humans and food producing animals. Oxidative methylation and glutathione conjugation is believed to be major pathways of As metabolism. Oxidative methylation is based on conversion of Arsenite in to mono-methylarsonic acid and di-methylarsenic acid in mammals. It has been confirmed that As is only methylated in the presence of glutathione or thiol compounds, suggesting that As is being methylated in trivalent states. Subsequently, non-conjugated trivalent arsenicals are highly reactive with thiol which converts the trivalent arsenicals in to less toxic pentavalent forms. The glutathione conjugate stability of As is the most important factor for determining the toxicity. It can lead to DNA damage by alerting enzyme profile and production of reactive oxygen and nitrogen species which causes the oxidative stress. Moreover, As causes immune-dysfunction by hindering cellular and humeral immune response. The present review discussed different metabolic pathways and toxic outcomes of arsenicals in mammals which will be helpful in health risk assessment and its impact on biological world.

[Arsenic speciation in rat plasma after oral administration of realgar and Niu Huang Jie Du Pian].

The arsenic species in rat plasma were studied after oral administration of realgar and Niu Huang Jie Du Pian (NHJDP) and the possible compatible effects of realgar was evaluated by comparing the pharmacokinetics of arsenic species after administration of realgar and NHJDP. The separation of the arsenicals was performed by a high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) technique. Dimethylarsinic acid (DMA) was found to be the main species in rats' plasma after dosing. No traces of arsenite [As(Ⅲ)], monomethylarsonic acid (MMA) or arsenate [As(Ⅴ)] were detected at any sampling time points. Compared with realgar administration alone, dose-normalized peak concentration(C(max)) and AUC(0-t) of DMA were significantly decreased by NHJDP administration, while the t(max) was significantly delayed with the clearance and apparent volume of distribution significantly increased, indicating that the pharmacokinetics of As from realgar was affected by other ingredients in the compound prescription of NHJDP.

Fluoride and arsenic exposure impairs learning and memory and decreases mGluR5 expression in the hippocampus and cortex in rats.

Fluoride and arsenic are two common inorganic contaminants in drinking water that are associated with impairment in child development and retarded intelligence. The present study was conducted to explore the effects on spatial learning, memory, glutamate levels, and group I metabotropic glutamate receptors (mGluRs) expression in the hippocampus and cortex after subchronic exposure to fluoride, arsenic, and a fluoride and arsenic combination in rats. Weaned male Sprague-Dawley rats were assigned to four groups. The control rats drank tap water. Rats in the three exposure groups drank water with sodium fluoride (120 mg/L), sodium arsenite (70 mg/L), and a sodium fluoride (120 mg/L) and sodium arsenite (70 mg/L) combination for 3 months. Spatial learning and memory was measured in Morris water maze. mGluR1 and mGluR5 mRNA and protein expression in the hippocampus and cortex was detected using RT-PCR and Western blot, respectively. Compared with controls, learning and memory ability declined in rats that were exposed to fluoride and arsenic both alone and combined. Combined fluoride and arsenic exposure did not have a more pronounced effect on spatial learning and memory compared with arsenic and fluoride exposure alone. Compared with controls, glutamate levels decreased in the hippocampus and cortex of rats exposed to fluoride and combined fluoride and arsenic, and in cortex of arsenic-exposed rats. mGluR5 mRNA and protein expressions in the hippocampus and mGluR5 protein expression in the cortex decreased in rats exposed to arsenic alone. Interestingly, compared with fluoride and arsenic exposure alone, fluoride and arsenic combination decreased mGluR5 mRNA expression in the cortex and protein expression in the hippocampus, suggesting a synergistic effect of fluoride and arsenic. These data indicate that fluoride and arsenic, either alone or combined, can decrease learning and memory ability in rats. The mechanism may be associated with changes of glutamate level and mGluR5 expression in cortex and hippocampus.

Alpha-lipoic acid protects oxidative stress, changes in cholinergic system and tissue histopathology during co-exposure to arsenic-dichlorvos in rats.

We investigated protective efficacy of α-lipoic acid (LA), an antioxidant against arsenic and DDVP co-exposed rats. Biochemical variables suggestive of oxidative stress, neurological dysfunction, and tissue histopathological alterations were determined. Male rats were exposed either to 50 ppm sodium arsenite in drinking water or in combination with DDVP (4 mg/kg, subcutaneously) for 10 weeks. α-Lipoic acid (50mg/kg, pos) was also co-administered in above groups. Arsenic exposure led to significant oxidative stress along, hepatotoxicity, hematotoxicity and altered brain biogenic amines levels accompanied by increased arsenic accumulation in blood and tissues. These altered biochemical variables were supported by histopathological examinations leading to oxidative stress and cell death. These biochemical alterations were significantly restored by co-administration of α-lipoic acid with arsenic and DDVP alone and concomitantly. The results indicate that arsenic and DDVP induced oxidative stress and cholinergic dysfunction can be significantly protected by the supplementation of α-lipoic acid.

Arsenic speciation in the blood of arsenite-treated F344 rats.

Arsenic speciation in blood can improve understanding of the metabolism and toxicity of arsenic. In this study, arsenic species in the plasma and red blood cells (RBCs) of arsenite-treated female F344 rats were characterized using anion exchange and size exclusion chromatography separation with inductively coupled plasma mass spectrometry (ICPMS) and electrospray ionization tandem mass spectrometry (ESI MS/MS) detection. Arsenite (iAs(III)), arsenate (iAs(V)), monomethylarsonic acid (MMA(V)), dimethylarsinic acid (DMA(V)), trimethylarsine oxide (TMAO(V)), monomethylmonothioarsonic acid (MMMTA(V)), and dimethylmonothioarsinic acid (DMMTA(V)) were detected in the plasma, with DMA(V) being the predominant metabolite. Upon oxidative pretreatment with 5% hydrogen peroxide (H2O2), plasma proteins released bound arsenic in the form of DMA(V) as the major species and MMA(V) as the minor species. The ratio of protein-bound arsenic to total arsenic decreased with increasing dosage of iAs(III) administered to the rats, suggesting a possible saturation of the binding capacity of the plasma proteins. The proportion of the protein-bound arsenic in the plasma varied among rats. In the H2O2-treated lysates of red blood cells of rats, DMA(V) was consistently found as the predominant arsenic species, probably reflecting the preferential binding of dimethylarsinous acid (DMA(III)) to rat hemoglobin. iAs(V), MMA(V), and trimethylarsine oxide (TMAO(V)) were also detected in the hydrogen peroxide-treated lysates of red blood cells. Importantly, DMMTA(V) and MMMTA(V) have not been reported in rat blood, and the present finding of DMMTA(V) and MMMTA(V) in the rat plasma is toxicologically relevant because these pentavalent thioarsenicals are more toxic than their counterparts DMA(V) and MMA(V). Identifying novel thiolated arsenicals and determining protein-bound arsenicals in the blood provide useful insights into the metabolism and toxicity of arsenic in animals.

Role of pigment epithelium-derived factor (PEDF) in arsenic-induced cell apoptosis of liver and brain in a rat model.

Although studies have shown that arsenic exposure can induce apoptosis in a variety of cells, the exact molecular mechanism of chronic arsenicosis remains unclear. Based on our previous study on human serum, the present study was to determine whether pigment epithelium-derived factor (PEDF) plays a role in the damage induced by chronic arsenic exposure in a rat model and to explore the possible signaling pathway involved. Thirty male Wistar rats were randomly divided into three groups and the arsenite doses administered were 0, 10, and 50 mg/L, respectively. The experiment lasted for 6 months. Our results showed that level of arsenic increased significantly in serum, liver, brain, and kidney in arsenic-exposed groups. It was indicated that PEDF protein was widely distributed in the cytoplasm of various types of cells in liver, brain, and kidney. PEDF protein level was only changed when the arsenite dose reached 50 mg/L in liver and brain, whereas it was not changed in the kidney. In order to investigate the possible mechanism of PEDF-exerted damages upon arsenite exposure, apoptosis in liver and brain was assessed. The proportion of apoptotic cells gradually increased with increasing arsenic administration. The ratio of Bax/Bcl-2 in the high arsenic group (50 mg/L) was significantly higher than that in the control group. Therefore, we thought PEDF played a role in cell apoptosis of liver and brain which induced by sodium arsenite exposure, and the results also demonstrated that Bax and Bcl-2 might be two key targets in the action of PEDF.

Probing the bioinorganic chemistry of toxic metals in the mammalian bloodstream to advance human health.

The etiology of numerous grievous human diseases, including Alzheimer's and Parkinson's Disease is not well understood. Conversely, the concentration toxic metals and metalloids, such as As, Cd, Hg and Pb in human blood of the average population is well established, yet we know strikingly little about the role that they might play in the etiology of disease processes. Establishing functional connections between the chronic exposure of humans to these and other inorganic pollutants and the etiology of certain human diseases is therefore viewed by many as one of the greatest challenges in the post-genomic era. Conceptually, this task requires us to uncover hitherto unknown biomolecular mechanisms which must explain how small doses of a toxic metal/metalloid compound (low µg per day) - or mixtures thereof - may eventually result in a particular human disease. The biological complexity that is inherently associated with mammals, however, makes the discovery of these mechanisms a truly monumental task. Recent findings suggest that a better understanding of the bioinorganic chemistry of inorganic pollutants in the mammalian bloodstream represents a fruitful strategy to unravel relevant biomolecular mechanisms. The adverse effect(s) that toxic metals/metalloid compounds exert on the transport of essential ultratrace elements to internal organs appear particularly pertinent. A brief overview of the effect that arsenite and Hg(2+) exert on the mammalian metabolism of selenium is presented.

Antagonistic role of tea against sodium arsenite-induced oxidative DNA damage and inhibition of DNA repair in Swiss albino mice.

Arsenic (As) contamination in groundwater is of increasing health concern in West Bengal, India. Arsenic has been associated with various human cancers, but the precise mechanism of its co-carcinogenic action is not clearly elucidated. Oxidative stress and defective repair mechanisms may promote accumulation of mutations and may be a stepping stone for carcinogenesis. Prevention of arsenic-induced oxidative stress and repair inhibition may reduce the chances of initiation of cancer. Tea polyphenols are reported to have excellent chemopreventive properties against cancer. This study aimed to elucidate the role of tea against arsenic-induced formation of 8-hydroxy-2'-deoxyguanosine (8OHdG) and arsenic-suppressed DNA repair in Swiss albino mice. Both green and black tea gave fruitful results in the reduction of 8OHdG and 8-oxoguanine DNA glycosylase (OGG1) in Swiss albino mice administered sodium arsenite (As III). DNA repair enzymes--such as PARP1, DNA ß-polymerase, XRCC1, DNA ligase III, DNA protein kinase (catalytic subunit), XRCC 4, DNA ligase IV, and DNA topoisomerase IIß--were induced by the phytochemicals at both the protein and genetic levels. Thus, tea polyphenols may prove effective in treating arsenic-induced carcinogenesis.

Mouse arsenic (+3 oxidation state) methyltransferase genotype affects metabolism and tissue dosimetry of arsenicals after arsenite administration in drinking water.

Arsenic (+3 oxidation state) methyltransferase (As3mt) catalyzes methylation of inorganic arsenic (iAs) producing a number of methylated arsenic metabolites. Although methylation has been commonly considered a pathway for detoxification of arsenic, some highly reactive methylated arsenicals may contribute to toxicity associated with exposure to inorganic arsenic. Here, adult female wild-type (WT) C57BL/6 mice and female As3mt knockout (KO) mice received drinking water that contained 1, 10, or 25 ppm (mg/l) of arsenite for 33 days and blood, liver, kidney, and lung were taken for arsenic speciation. Genotype markedly affected concentrations of arsenicals in tissues. Summed concentrations of arsenicals in plasma were higher in WT than in KO mice; in red blood cells, summed concentrations of arsenicals were higher in KO than in WT mice. In liver, kidney, and lung, summed concentrations of arsenicals were greater in KO than in WT mice. Although capacity for arsenic methylation is much reduced in KO mice, some mono-, di-, and tri-methylated arsenicals were found in tissues of KO mice, likely reflecting the activity of other tissue methyltransferases or preabsorptive metabolism by the microbiota of the gastrointestinal tract. These results show that the genotype for arsenic methylation determines the phenotypes of arsenic retention and distribution and affects the dose- and organ-dependent toxicity associated with exposure to inorganic arsenic.

Co-exposure to arsenic and fluoride on oxidative stress, glutathione linked enzymes, biogenic amines and DNA damage in mouse brain.

We studied the effects of combined exposure to arsenic and fluoride on (i) brain biogenic amines, oxidative stress and its correlation with glutathione and linked enzymes; (ii) alterations in the structural integrity of DNA; and (iii) brain and blood arsenic and fluoride levels. Efficacy of alpha-tocopherol in reducing these changes was also determined. Male mice were exposed to sodium meta arsenite (50 ppm) and sodium fluoride (50 ppm) individually and in combination for ten weeks. Animals were given vitamin E supplementation (5 mg/kg, i.m., alternate days) throughout the experiment. Exposure to arsenic and fluoride significantly decreased the levels of brain biogenic amines. However; acetyl cholinesterase (AChE) and monoamine oxidase (MAO) activities showed an increase on fluoride exposure. There was also an increase in reactive oxygen species, thiobarbituric acid reactive species level, glutathione S-transferase and glutathione peroxidase activities and decreased superoxide dismutase activity, GSH:GSSG ratio, glucose 6-phosphate dehydrogenase activity. Combined exposure to these toxicants produced more pronounced effects on AChE, MAO, SOD and catalase activities. Infrared spectra showed less toxicity during combined exposure as the characteristic peaks of cytosine and alpha-helical structure of DNA were observed in normal and arsenic plus fluoride-exposed animals. Vitamin E reduced brain fluoride level and tissue oxidative stress but had no effect on arsenic. Combined exposure to arsenic and fluoride does not necessarily lead to more pronounced toxicity and interestingly exhibit some antagonistic effects. Vitamin E supplementation may be of added value in reverting some of the toxic effects.

Genotoxicity of sodium arsenite and DNA fragmentation in ovarian cells of rat.

Present study examined the genotoxic effects of arsenite in ovarian tissue of rat at 56 days of age. Immature (28 days old) female rats were exposed to different doses (50, 100, and 200 ppm) of sodium arsenite in drinking water for 28 days. DNA damage in ovarian tissue was measured by comet assay. All doses induced significant decrease in ovarian weight in a dose-dependent manner compared to control, more prominently at (P<0.001) 100 and 200 ppm. All the comet assay parameters showed significant difference with arsenite treatment compared to control group. In treatment groups, mean number of cells with intact DNA decreased while, mean comet number increased (P<0.001) in a dose-dependent manner compared to control. Significant decrease (P<0.05) was observed in mean comet length, height, comet head diameter and %DNA in comet head of high dose groups compared to control group. Dose dependent increase was found in mean comet tail length, %DNA in tail, tail moment and olive tail moment in high dose groups compared to control group. The study indicates that arsenic caused DNA damage to ovarian cells particularly at high doses and ensure comet assay as an effective method to detect DNA damage in tissue caused by metals.

Chronic toxicity of As(III) in mammals: the role of (GS)(2)AsSe(-).

Millions of people are currently exposed to a multitude of environmentally persistent toxic metals and metalloid compounds mainly through the ingestion of drinking water and food. Despite the fact that biomonitoring studies have revealed several toxic metals to be present in the bloodstream of the general population, the interpretation of the established blood concentrations with regard to their health relevance continues to be an active research area. To this end, a better understanding of the bioinorganic chemistry of individual metals and metalloid compounds in the mammalian bloodstream could greatly advance the interpretation of the available biomonitoring data. Arsenite represents a case in point, since >100 million people are currently exposed to unsafe levels of inorganic arsenic via drinking water. The elucidation of the underlying biomolecular mechanism(s) of toxicity is therefore of the utmost importance and could involve the antagonistic toxic effect between arsenite and selenite, which was discovered in mammals approximately 70 years ago. After a concise overview of animal studies that aimed to understand this trace element antagonism at the molecular level, the in vivo formation and biliary excretion of the seleno-bis(S-glutathionyl) arsinium ion, (GS)(2)AsSe(-), is introduced as a likely biomolecular basis. Arguments in favor of a critical involvement of (GS)(2)AsSe(-) in the chronic toxicity and carcinogenicity of arsenite are presented. The in vivo formation of this toxicologically relevant metabolite in the mammalian bloodstream (mediated by erythrocytes) indicates that the elucidation of bioinorganic chemistry-related mechanisms that take place in the bloodstream represents a promising research strategy to better understand the etiology of numerous human diseases some of which may be ultimately caused by the low level exposure to certain inorganic pollutants.

Enzymatic digestion and chromatographic analysis of arsenic species released from proteins.

A method combining gel filtration chromatography (GFC), protease digestion, and ion pair chromatography with inductively coupled plasma mass spectrometry detection was developed for the determination of arsenic species bound to proteins. The method was first established by examining the interactions of two model proteins, metallothionein (MT) and hemoglobin, with three reactive trivalent arsenic species. It was then successfully applied to the speciation of arsenic in red blood cells of rats. Inorganic arsenite (iAs(III)), monomethylarsonous acid (MMA(III)), and dimethylarsinous acid (DMA(III)) were efficiently released from the proteins by protease digestion at pH 8.0, with the recovery ranging from 93% to 106%. There was no oxidation of iAs(III) or MMA(III) during the protease digestion process. Up to 61% DMA(III) (the least stable arsenic species) was unchanged, and the rest was oxidized to the pentavalent dimethylarsinic acid (DMA(V)). The arsenic species in the red blood cells of control rats was present as DMA(III) complex with hemoglobin. The method enabling the determination of the specific arsenic species that bind to cellular proteins is potentially useful for studying arsenic distribution, metabolism, and toxicity.

Effects of arsenic exposure from drinking water on spatial memory, ultra-structures and NMDAR gene expression of hippocampus in rats.

Epidemiological investigations indicate that chronic arsenic exposure can damage neurobehavioral function in children. The present study was aimed to study the effects of arsenic exposure from drinking water on the spatial memory, and hippocampal ultra-structures and N-methyl-d-aspartate receptor (NMDAR) gene expression in rats. Sprague-Dawley rats were assigned to four groups: rats in control group drank regular water, rats in other groups drank water with final arsenic concentration of 2.72 mg/L (group A), 13.6 mg/L (group B) and 68 mg/L (group C), respectively, for 3 months. The levels of arsenic in blood serum and hippocampus were monitored. Rats were tested in Morris water maze (MWM) for memory status. Samples of hippocampus were collected from two rats in each group for transmission electron microscopic study and the detection of NMDAR expression by RT-PCR. The rats in group C showed a significant delay in hidden platform acquisition. Neurons and endothelial cells presented pathological changes and the expression of NR2A was down-regulated in hippocampus in arsenic exposed rats. Our data indicated that arsenic exposure of 68 mg/L caused spatial memory damage, of which the morphological and biochemical bases could be the ultra-structure changes and reduced NR2A expression in hippocampus.

Impact of arsenic in foodstuffs on the people living in the arsenic-affected areas of West Bengal, India.

Although the accumulation of arsenic (As) in human blood is linked with some diseases and with occupational exposure, there are few reports on speciation of As in blood. On the basis of our earlier article, elevated level of arsenicals in human urine and blood were found in the ex-exposed population via As-containing drinking water. The aim of the present study was to get an insight on impact of As in foodstuffs on the people living in the As-affected areas. Moreover, speciation of arsenicals in urine, and water-samples found in arsenobetaine (AsB). Since sampling population (n=25) was not taking any seafood, As in foodstuffs was thought to be the prime source for this discrepancy. So, speciation of methanol extract of freeze-dried red blood cells (RBCs) and foodstuffs, and trichloro acetic acid (TCA) treated plasma by high performance liquid chromatography-inductively coupled argon plasma mass spectrometer (HPLC-ICP MS) collected from the study population (n=33) was carried out to support our hypothesis. Results showed that urine contained AsB (1.7%), arsenite (iAs(III)) (14.3), arsenate (iAs(V)) (4.9), monomethylarsonous acid (MMA(III)) (0.64), monomethylarsonic acid (MMA(V)) (13.6), dimethylarsinous acid (DMA(III)) (7.7), and dimethylarsinic acid (DMA(V)) (65.4). Blood contained 21.3 microg L(- 1) (mean) As and of which 27.3% was in plasma and 72.7% in RBCs. RBCs contained AsB (21.6%) and DMA(V) (78.4) and blood plasma contained AsB (12.4%), iAs(III) (25.9), MMA(V) (30.3), and DMA(V) (31.4). Furthermore, speciation of As in foodstuffs showed that most of them contained AsB (3.54-25.81 microg kg(- 1)) (25.81-312.44 microg kg(- 1)) along with iAs(III) (9.62-194.93), iAs(V) (17.63-78.33), MMA(V) (9.47-73.22) and DMA(V) (13.43-101.15) that supported the presence of AsB and elevated As in urine and blood samples of the present study group. Inorganic As (iAs) predominates in rice (67.17-86.62%) and in spices (40-90.35%), respectively over organic As. So, As in the food chain is a real threat to human health.