Teratogenic vulnerability of Wistar rats to diphenyl ditelluride

Diphenyl ditelluride intoxication triggers histological changes in liver, kidney, and lung of mice

Tellurium compounds may be cytotoxic to different cells types. Thus, this work evaluated the effect of diphenyl ditelluride ((PhTe)2), an organotellurium commonly used in organic synthesis, on the morphology of liver, kidney, and lung. Adult mice were acutely (a subcutaneous single dose: 250 μmol/kg) or subchronically (one daily subcutaneous dose: 10 or 50 μmol/kg for 7 and 14 days) exposed to (PhTe)2. Afterwards, the histological analyses of liver, kidney, and lungs were performed. Liver histology revealed that the hepatocytes of mice subchronically exposed to (PhTe)2 presented cytoplasmic vacuolization, hydropic degeneration, and hyperchromatic nuclei. Subchronic exposure to 50 μmol/kg (PhTe)2 also caused hepatic necrosis. Microvesicular and macrovesicular steatosis were identified in liver of mice acutely exposed to (PhTe)2. Acute and subchronic intoxication with (PhTe)2 induced changes on epithelial cells of renal tubules, namely, loss of brush border and cytoplasmatic vacuolization. Atrophy and hypertrophy, cast proteinaceous formation, and acute tubular necrosis were also identified in renal tissue. Mice subchronically exposed to 50 μmol/kg (PhTe)2 developed intra-alveolar edema and alveolar wall congestion in some areas of lungs. Acute exposure to (PhTe)2 did not cause histological changes in lungs. Our data show that (PhTe)2 may be considered a histotoxic agent for liver, kidney, and lung.

Signaling mechanisms and disrupted cytoskeleton in the diphenyl ditelluride neurotoxicity

Evidence from our group supports that diphenyl ditelluride (PhTe)₂ neurotoxicity depends on modulation of signaling pathways initiated at the plasma membrane. The (PhTe)₂-evoked signal is transduced downstream of voltage-dependent Ca²⁺ channels (VDCC), N-methyl-D-aspartate receptors (NMDA), or metabotropic glutamate receptors activation via different kinase pathways (protein kinase A, phospholipase C/protein kinase C, mitogen-activated protein kinases (MAPKs), and Akt signaling pathway). Among the most relevant cues of misregulated signaling mechanisms evoked by (PhTe)₂ is the cytoskeleton of neural cells. The in vivo and in vitro exposure to (PhTe)₂ induce hyperphosphorylation/hypophosphorylation of neuronal and glial intermediate filament (IF) proteins (neurofilaments and glial fibrillary acidic protein, resp.) in different brain structures of young rats. Phosphorylation of IFs at specific sites modulates their association/disassociation and interferes with important physiological roles, such as axonal transport. Disrupted cytoskeleton is a crucial marker of neurodegeneration and is associated with reactive astrogliosis and apoptotic cell death. This review focuses the current knowledge and important results on the mechanisms of (PhTe)₂ neurotoxicity with special emphasis on the cytoskeletal proteins and their differential regulation by kinases/phosphatases and Ca²⁺-mediated mechanisms in developmental rat brain. We propose that the disrupted cytoskeletal homeostasis could support brain damage provoked by this neurotoxicant.

Diphenyl ditelluride induces anxiogenic-like behavior in rats by reducing glutamate uptake

Anxiety-related disorders are a common public health issue. Several lines of evidence suggest that altered glutamatergic neurotransmission underlies anxiety. The present study evaluated the effect of diphenyl ditelluride [(PhTe)2] exposure on the behavioral performance of rats and examined whether the behavioral effects could be attributed to changes in the modulation of glutamatergic function. Rats were exposed to (PhTe)2 (subcutaneously) during 8 weeks-final dose one third LD50 (124 μg/kg). The testing schedule included elevated plus-maze, open-field, T-maze, rotorod, and Morris water maze tests. Synaptosomal basal [(3)H] glutamate release and uptake were also evaluated. The time spent in the open arm and the ratio of time spent in the open arm/total were decreased in the (PhTe)2 group. Furthermore, the [(3)H] glutamate uptake was decreased in this experimental group. The results suggest that exposure to (PhTe)2 did not change motor abilities whereas it may result in anxiogenic-like behavior, induced by changes in the glutamatergic system at the pre-synaptic level.

Sub-acute administration of (S)-dimethyl 2-(3-(phenyltellanyl) propanamido) succinate induces toxicity and oxidative stress in mice: unexpected effects of N-acetylcysteine

The organic tellurium compound (S)-dimethyl 2-(3-(phenyltellanyl) propanamide) succinate (TeAsp) exhibits thiol-peroxidase activity that could potentially offer protection against oxidative stress. However, data from the literature show that tellurium is a toxic agent to rodents. In order to mitigate such toxicity, N-acetylcysteine (NAC) was administered in parallel with TeAsp during 10 days. Mice were separated into four groups receiving daily injections of (A) vehicle (PBS 2.5 ml/kg, i.p. and DMSO 1 ml/kg, s.c.), (B) NAC (100 mg/kg, i.p. and DMSO s.c.), (C) PBS i.p. and TeAsp (92.5 μmol/kg, s.c), or (D) NAC plus TeAsp. TeAsp treatment started on the fourth day. Vehicle or NAC-treated animals showed an increase in body weight whereas TeAsp caused a significant reduction. Contrary to expected, NAC co-administration potentiated the toxic effect of TeAsp, causing a decrease in body weight. Vehicle, NAC or TeAsp did not affect the exploratory and motor activity in the open-field test at the end of the treatment, while the combination of NAC and TeAsp produced a significant decrease in these parameters. No DNA damage or alterations in cell viability were observed in leukocytes of treated animals. Treatments produced no or minor effects on the activities of antioxidant enzymes catalase, glutathione peroxidase and glutathione reductase, whereas the activity of the thioredoxin reductase was decreased in the brain and increased the liver of the animals in the groups receiving TeAsp or TeAsp plus NAC. In conclusion, the toxicity of TeAsp was potentiated by NAC and oxidative stress appears to play a central role in this process.

Organochalcogens inhibit mitochondrial complexes I and II in rat brain: possible implications for neurotoxicity

Organochalcogens, such as organoselenium and organotellurium compounds, can be neurotoxic to rodents. Since mitochondrial dysfunction plays a pivotal role in neurological disorders, the present study was designed to test the hypothesis that rat brain mitochondrial complexes (I, II, I-III, II-III and IV) could be molecular targets of organochalcogens. The results show that organochalcogens caused statistically significant inhibition of mitochondrial complex I activity, which was prevented by preincubation with NADH and fully blunted by reduced glutathione (GSH). Mitochondrial complex II activity remained unchanged in response to (PhSe)₂ treatment. Ebs and (PhTe)₂ caused a significant concentration-dependent inhibition of complex II that was also blunted by GSH. Mitochondrial complex IV activity was not modified by organochalcogens. Collectively, Ebs, (PhSe)₂ and (PhTe)₂ were more effective inhibitors of brain mitochondrial complex I than of complex II, whereas they did not affect complex IV. These observations are consistent with organochalcogens inducing mitochondrial complex I and II inhibition via their thiol-oxidase-like activity, with Ebs, (PhSe)₂ and (PhTe)₂ effectively oxidising critical thiol groups of these complexes.

Evaluation of tellurium toxicity in transformed and non-transformed human colon cells

Diphenyl ditelluride (DPDT) and tellurium tetrachloride (TeCl(4)) were evaluated for toxicity in transformed (HT-29, Caco-2) and non-transformed colon cells (CCD-18Co). Significant decreases in viability were observed with DPDT exposure in HT-29 (62.5-1000 μM), Caco-2 (31.25-1000 μM) and CCD-18Co cells (500-1000 μM) and with TeCl(4) in HT-29 (31.25-1000 μM), Caco-2 (31.25-1000 μM) and CCD-18Co cells (500-1000 μM). Light microscopy confirmed viability analysis. Significant increases in caspase 3/7 and 9 activity were observed with DPDT in HT-29 (500-1000 μM) and CCD-18Co cells (1000 μM) indicating apoptosis. No significant increases in caspases were seen with TeCl(4) indicating necrosis. Apoptosis or necrosis was confirmed with fluorescent staining (FITC-Annexin, Hoechst 33342 and Ethidium Homodimer). Significant decreases in GSH/GSSG ratio were observed with DPDT in HT-29 (62.5-1000 μM), and CCD-18Co cells (1000 μM) and with TeCl(4) in HT-29 (62.5-1000 μM) and CCD-18Co cells (250-1000 μM). We concluded that cells treated with DPDT resulted in apoptosis and TeCl(4) treatment in necrosis. GSH/GSSG ratio shifts indicate oxidative mechanisms are involved.

Kinetic studies on the inhibition of creatine kinase activity by 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one in the cerebral cortex of rats

Tellurium has been used as an industrial component of many alloys and in the electronic industry. Organotellurium compounds can cause poisoning which leads to neurotoxic symptoms such as significant impairment of learning, spatial memory and are potentially neurotoxic to human beings. However, the molecular mechanisms of neurotoxicity of organotellurium compounds are not well understood. Considering that creatine kinase plays a key role in energy metabolism of tissues with intermittently high and fluctuating energy requirements, such as nervous tissue, the main objective of this study was to investigate the mechanisms by which 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one inhibit creatine kinase activity, a key enzyme of energy homeostasis, in the cerebral cortex of 30-day-old Wistar rats. For the kinetic studies, the Lineweaver-Burk plot was used to characterize the mechanisms of enzyme inhibition by 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one. The results suggested that this compound inhibits creatine kinase activity by two different mechanisms: competition with ADP and oxidation of critical sulfhydryl groups for the functioning of the enzyme. The potential for inhibition of creatine kinase to occur in vivo may contribute to the neurotoxicity observed by this organochaocogen.

Extreme selenium and tellurium contamination in soils--an eighty year-old industrial legacy surrounding a Ni refinery in the Swansea Valley

Elevated levels of selenium (maximum 200 mg/kg) and tellurium (maximum 11 mg/kg) are reported in topsoils (<5 cm) from around a long-established nickel refinery at Clydach in the Lower Swansea Valley, UK. Se and Te are correlated with each other and when these data are plotted as contour diagrams they show a concentric pattern centred on the refinery site. The origin of the Se and Te contamination is investigated. A review of the changes in the refinery practices at the site is presented and used to link the soil contamination to industrial pollution which took place over 80 years ago. The most recent air quality data available cannot rule out some Se contamination up to 2003.

Acute exposure to diphenyl ditelluride causes oxidative damage in rat lungs

The present study evaluated the effect of acute exposure to diphenyl ditelluride [(PhTe)(2)] on oxidative status in lungs of rats. Rats were exposed to a single subcutaneous application of (PhTe)(2) at the doses of 0.3, 0.6, 0.9 μmol/kg or vehicle. After 72 h of exposure to (PhTe)(2), biochemical parameters of oxidative stress were carried out in lungs of rats. The lungs of rats exposed to (PhTe)(2) showed an increase in the levels of lipid peroxidation, reactive species and non-protein thiol. Alterations in superoxide dismutase activity were observed at all tested doses. (PhTe)(2) caused an increase in catalase activity and a reduction in ascorbic acid levels at the dose of 0.9 μmol/kg. The oxidative damage was more pronounced in animals treated with the highest dose of (PhTe)(2). Thus, this study demonstrated that acute exposure to (PhTe)(2) induced oxidative damage and an adaptive response of antioxidants in pulmonary tissue of rats.

Comparison of the antioxidant properties and the toxicity of p,p'-dichlorodiphenyl ditelluride with the parent compound, diphenyl ditelluride

The hypothesis to be tested in this study is whether the introduction of the chloro group into diphenyl ditelluride molecule (p,p'-dichlorodiphenyl ditelluride, compound 1b) alters the antioxidant and scavenging activity of diphenyl ditelluride (compound 1a) in vitro. The results revealed that 1a and 1b had a potent antioxidant activity in vitro. However, the introduction of a functional group, chloro, into diphenyl ditelluride molecule (1b) did not cause great alterations in the antioxidant action of diphenyl ditelluride against lipid peroxidation, protein carbonyl, and scavenging of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) and 2,2'-diphenyl-1-picrylhydrazyl radicals. Based on the in vitro results, different doses (0.25 and 0.75 µmol/kg) of 1a and 1b or vehicle (canola oil, 1 ml/kg) were administered to rats to investigate if the presence of chloro into diphenyl ditelluride molecule reduces its toxicity. The data demonstrate that the chloro group introduced into diphenyl ditelluride molecule did not alter the acute oral toxicity in rats. The administration of compound 1a in rats only altered the urea level, while compound 1b caused alterations in all toxicological parameters analyzed (alanine aminotransferase and aspartate aminotransferase activities, urea and creatinine levels) in plasma of rats. The results of the present investigation support similar antioxidant and scavenging activities of 1a and 1b in rat liver homogenate in vitro. Furthermore, the presence of chloro into diphenyl ditelluride molecule did not alter the mortality index but increased toxicity of diphenyl ditelluride in rats.

Tellurium: an element with great biological potency and potential

Tellurium has long appeared as a nearly 'forgotten' element in Biology, with most studies focusing on tellurite, tellurate and a handful of organic tellurides. During the last decade, several discoveries have fuelled a renewed interest in this element. Bioincorporation of telluromethionine provides a new approach to add heavy atoms to selected sites in proteins. Cadmium telluride (CdTe) nanoparticles are fluorescent and may be used as quantum dots in imaging and diagnosis. The antibiotic properties of tellurite, long known yet almost forgotten, have attracted renewed interest, especially since the biochemical mechanisms of tellurium cytotoxicity are beginning to emerge. The close chemical relationship between tellurium and sulfur also transcends into in vitro and in vivo situations and provides new impetus for the development of enzyme inhibitors and redox modulators, some of which may be of interest in the field of antibiotics and anticancer drug design.

Effect of in vitro exposure of human serum to 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one on oxidative stress

The objective of this study was to verify the effect of the organochalcogen 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one on some parameters of oxidative stress in human serum. Serum of volunteers were incubated for 30 min in the presence or absence of 1, 10, or 30 microM of 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one and oxidative stress was measured. First, we tested the influence of the compound on 1,1-diphenyl-2-picrylhydrazyl (DPPH(*)) radical-scavenging and verified that the organotellurium did not have any antioxidant properties. The organochalcogen was capable to enhance TBARS but the compound was not able to alter carbonyl assay. Furthermore, the organochalcogen provoked a reduction of protein thiol groups measured by the sulfhydryl assay. Moreover, the organotellurium enhanced the activity of catalase and superoxide dismutase, inhibited the activity of glutathione peroxidase and did not modify the glutathione S-transferase activity. Furthermore, nitric oxide production and hydroxyl radical activity were not affected by the compound. Our findings showed that this organochalcogen induces oxidative stress in human serum, indicating that this compound is potentially toxic to human beings.

Exposure to diphenyl ditelluride, via maternal milk, causes oxidative stress in cerebral cortex, hippocampus and striatum of young rats

The present study evaluated the effect of diphenyl ditelluride [(PhTe)(2)] exposure to mothers on the cerebral oxidative status of their offspring. The dams received (PhTe)(2) or canola oil via subcutaneous injection once daily during the first 14 days of lactational period. At post natal day 28, biochemical parameters of oxidative stress were evaluated in cerebral structures-cortex, hippocampus and striatum-of young rats. Exposure to (PhTe)(2) increased lipid peroxidation levels and inhibited delta-ALA-D, catalase and SOD activities in hippocampus and striatum of young rats. (PhTe)(2) induced changes in the levels of non-enzymatic antioxidant defenses in cortex and striatum of young rats. The exposure to (PhTe)(2), via maternal milk, caused oxidative stress in cerebral structures of young rats. Thus, the possible role of disrupted prooxidant/antioxidant balance in (PhTe)(2) toxicity was demonstrated. These results highlighted a possible molecular mechanism involved in toxicity caused by (PhTe)(2).

Differential inhibition of high and low Mr thioredoxin reductases of parasites by organotelluriums supports the concept that low Mr thioredoxin reductases are good drug targets

Thioredoxin reductase (TrxR), a NADPH-dependent disulfide oxidoreductase, is vital in numerous cellular processes including defence against reactive oxygen species, cell proliferation and signal transduction. TrxRs occur in 2 forms, a high Mr enzyme characterized by those of mammals, the malaria parasite Plasmodium falciparum and some worms, and a low Mr form is present in bacteria, fungi, plants and some protozoan parasites. Our hypothesis is that the differences between the forms can be exploited in the development of selective inhibitors. In this study, cyclodextrin- and sulfonic acid-derived organotelluriums known to inhibit mammalian TrxR were investigated for their relative efficacy against P. falciparum TrxR (PfTrxR), a high Mr enzyme, and Trichomonas vaginalis TrxR (TvTrxR), a low Mr form of TrxR. The results suggest that selective inhibition of low Mr TrxRs is a feasible goal.

Repeated administration of diphenyl ditelluride induces hematological disorders in rats

In the present study, we investigated potential toxic effects of diphenyl ditelluride, as measured by biochemical and hematological parameters. Rats were given a daily dose of 0.3 micromol/kg diphenyl ditelluride by subcutaneous route and sacrificed at different times (24 and 48 h). Hepatic and renal TBARS levels were changed by diphenyl ditelluride exposure at the dose 0.9 micromol/Kg in rats. Diphenyl ditelluride exposure demonstrated an increase in AST (aspartate aminotransferase), ALT (alanine aminotransferase) and LDH (lactate dehydrogenase) activities. Plasma creatinine and urea levels increase after diphenyl ditelluride exposure. Diphenyl ditelluride also produced a significant decrease in plasma triglyceride and cholesterol levels. In contrast, this compound, at all doses tested, induced a marked increase in total leukocyte counts. The present study suggests that diphenyl ditelluride induces hematological disorders and provides evidence for renal and hepatic toxicity in rats.

Ebselen and diorganylchalcogenides decrease in vitro glutamate uptake by RAT brain slices: Prevention by DTT and GSH

The purpose of this study was to investigate the possible involvement of the glutamatergic system in the neurotoxicity of diorganylchalcogenides or organochalcogenides from slices of cerebral cortex in different ages of development: 12- and 60-day-old rats. Glutamate uptake was evaluated in cortical slices of 12 and 60 days old rats. Cortex slices were incubated with three different organochalcogenides with or without reduced glutathione or dithiothreitol. At 100 microM, ebselen, diphenyl diselenide (PhSe)2 and diphenyl ditelluride (PhTe)2 in vitro inhibited the [3H]glutamate uptake in both age. Both 60-day-old rats and for 12-day-old rats, GSH and DTT prevented the (PhTe)2-induced inhibition of glutamate uptake but did not protect the inhibition caused by ebselen and (PhSe)2. These findings suggest that the neurotoxicity of organochalcogenides could be related to their effects on brain glutamate uptake, conceivably involving a redox modulation of reactive amino acids from the glutamate transporter proteins.

Sub-chronic exposure of adult male rats to diphenyl ditelluride did not affect the development of their progeny

The present study was undertaken to evaluate the toxicity of diphenyl ditelluride [(PhTe)(2)] exposure on the progeny of Wistar male rats. Male rats were exposed to (PhTe)(2) subcutaneously for 4 weeks (wk) at the dose of 0.006 mg/kg and 8-wk at the dose of 0.003 mg/kg, prior to mating with unexposed females. The body and sex organ weights of male rats were not affected in both 4- and 8-wk (PhTe)(2)-exposed groups. The gravid uterus weight and the body weight gain (overall or corrected) during the pregnancy were not statistically different to those obtained from females mated with control males. The number of implantation sites, resorptions and live and dead fetuses were not affected by male exposure to (PhTe)(2). Fetal body weight and crown-rump length were not affected, as well. Examination of the fetuses from both exposed groups for external and skeletal changes did not reveal any male-mediated effect of (PhTe)(2). The current study indicated that (PhTe)(2) given sub-chronically (4- or 8-wk) to male rats had no adverse effects on their progeny.

Repeated administration of diphenyl diselenide to pregnant rats induces adverse effects on embryonic/fetal development

The present study was carried out to investigate the effects of diphenyl diselenide, (PhSe)(2), on embryo-fetal development. Dams were treated subcutaneously with 1.5, 3.0 and 6.0 mg/kg (PhSe)(2) from days 6 to 15 of pregnancy. After cesarean section at gestation day (GD) 20, external and skeletal abnormalities were evaluated. A decrease in maternal body weight gain was found in (PhSe)(2) groups, indicating maternal toxicity. There was a reduction in the fetal weight and in crown-rump (CR) length of fetuses at three doses tested. The occipito-nasal length decreased in fetuses from dams exposed to 3.0 mg/kg (PhSe)(2). Signs of delayed ossification in the skull, sternebrae and limbs were observed in all (PhSe)(2) groups, revealing a relation between morphological alterations and growth retardation in fetuses, but none of the changes appeared to be dose-dependent. Exposure of dams to (PhSe)(2) resulted in altered placental morphology that may have contributed to adverse reproductive outcomes. We concluded that (PhSe)(2) is toxic to dams and induces developmental delay of the fetal skeleton, but does not cause externally visible malformations in rat fetuses, in this experimental procedure.

Screening of potentially toxic chalcogens in erythrocytes

Previous literature reports have demonstrated that a number of human diseases, including inflammation and cancer, can be caused by environmental and occupational exposure to toxic compounds, via DNA damage, protein modifications, or lipid peroxidation. The present study was undertaken to screen the toxicity of a variety of chalcogens using erythrocytes as a model of cell injury. The toxicity of these compounds was evaluated via quantification of hemolysis and lipid peroxidation. The present investigation shows that diphenyl ditelluride and phenyl tellurides are toxic to erythrocytes. The organoselenium compounds were not toxic to erythrocytes even when tested at high concentrations and with a hematocrit of 45%. The hemolytic effect of tellurides was not positively correlated with thiobarbituric acid-reactive substance (TBARS) production suggesting that lipid peroxidation is not involved in the hemolysis provoked by organotellurium compounds. The results suggest that chalcogen compounds may be toxic to human erythrocytes, depending on their structure.

Diphenyl diselenide changes behavior in female pups

Diphenyl diselenide, (PhSe)(2), is an organoselenium compound that affects a number of neuronal processes. The effect of maternal subcutaneous (s.c.) injection of 25 mg/kg (PhSe)(2) once daily during early postnatal development (from PND 1 to 21) was evaluated in offspring of Wistar rats. The physical and neural reflexes were recorded at pre-weaning period. The behavioral changes in the elevated plus-maze (EPM), open-field and rotarod tasks were performed in 28-day-old pups. Selenium brain status was significantly increased ( approximately 41%) in rat pups. Statistically significant decreases in body weight were observed during lactation period in male and female pups exposed to 25 mg/kg (PhSe)(2). There were no dose-related changes on landmarks indicative of physical and reflexologic parameters of development in rats. (PhSe)(2) induced a disinhibitory effect in EPM behavior according to gender. Specifically, exposure to (PhSe)(2) increased entries and duration in the open arms of the EPM in females but not in males. Locomotor activity and rearing increased by (PhSe)(2) exposure in both male and female offspring in the open field. Both groups were similar in response to motor coordination in the rotarod. We concluded that maternal (PhSe)(2) exposure during lactation increased selenium levels in the pup brain and caused changes on developmental and behavioral parameters of Wistar rat offspring.

Assessment of reproductive toxicity in male rats following acute and sub-chronic exposures to diphenyl diselenide and diphenyl ditelluride

The present study was conducted to evaluate the toxicity of the exposure to diphenyl diselenide [(PhSe)2] and diphenyl ditelluride [(PhTe)2] on reproductive system in Wistar rats. Adult male rats were exposed intraperitonealy (acute) or subcutaneously (sub-chronic, during 4 or 8 weeks) to (PhSe)2 or (PhTe)2 prior to mating. A number of biochemical parameters in rat testes were examined, such as delta-aminolevulinate dehydratase (delta-ALA-D) activity, lipid peroxidation, glycogen content and components of the antioxidant defenses (superoxide dismutase (SOD) activity and ascorbic acid concentration). Furthermore, a possible effect on fertility and reproductive performance in male rats were studied. Sperm counts of caudal epididymis were also evaluated. No lethality was noted in any group. Reduction on body weight in rats which received (PhTe)2 was only evidenced in acute exposure, while (PhSe)2-exposed rats presented significant loss of body weight in acute and 4 week-exposure. Mating and fertility indexes were not affected after acute and sub-chronic exposure. Regarding other parameters studied, except for a decrease in testes glycogen content in acutely (PhSe)2-treated group, no alterations were found in treated groups. Sperm counts of rats treated acutely and sub-chronically were unaffected by drugs exposure. Histological evaluation revealed no modification on testicular tissue in rats exposed to (PhSe)2 and (PhTe)2. The results suggest the absence of the male reproductive toxicity induced by (PhSe)2 and (PhTe)2 administered intraperitonealy (acute) or subcutaneously (sub-chronical) to adult rats Wistar.

Exposure of mothers to diphenyl ditelluride during the suckling period changes behavioral tendencies in their offspring

The long-lasting possible influence of maternal exposure to 0.03 mg/kg of diphenyl ditelluride during the first 14 days of lactational period on later offspring behavior was examined in Wistar rats. Open-field locomotor activity, spontaneous alternation in the T-maze, behavior in the elevated plus-maze, motor coordination in the coat-hanger and rotorod tasks were evaluated in 30 day old pups. There were no significant specific overt signs of maternal intoxication. There were a small (less than 5%) but significant transitory differences in the body weight gain of pups between exposed and control groups, which were apparent from day 30 of suckling. Locomotor activity in the open-field task was similar between telluride and control groups. In the coat-hanger test, the latency before falling for the tellurium group was higher than that of the control group. However, the behavior of both groups was similar in the rotorod test and spontaneous alternation in the T-maze. Tellurium-treated pups presented a higher number of entries and spent more time in the open arms of the elevated plus-maze than control pups. The behavioral alterations observed here after tellurium exposure can be cautiously interpreted as an indication of behavioral disinhibition. In conclusion, this study demonstrated that dam exposure to diphenyl ditelluride can cause subtle behavioral changes in the offspring, which can be related to neurotoxic effects of diphenyl ditelluride.

Teratogenic effects of diphenyl diselenide in Wistar rats

Diphenyl diselenide is an organoselenium compound with potential therapeutic use. The present study evaluates the effects of single maternal subcutaneous injection of 50 and 100mg/kg diphenyl diselenide [(PhSe)2] at gestational days (GD) 6, 10 or 17 in Wistar rats. The highest dose of (PhSe2 was also administered at GD 7-12. External and internal fetal soft-tissue examination was performed at GD 20. No mortality was observed in fetuses or dams at any (PhSe)2 treatment group. Neither did exposure to (PhSe)2 cause significant changes to fetal body weight, organ weight, or fetal size when administered at GD 6-8, 10-12 or 17. Exposure to 100mg/kg (PhSe)2 at GD 9 produced significant changes in fetal biometry (crown-rump (CR) length) and body weight. No significant increase in the proportion of fetuses with external visible abnormalities was observed in groups exposed to (PhSe)2. Skeletal anomalies were observed in fetuses in the GD 9-11 treatment groups and included incomplete ossification of cranial bones, misshapen and incomplete ossification of sternebrae, reduced sternebrae number, wavy and extra ribs, incomplete ossification of fore and hindpaw bones and incomplete ossification of sacral and caudal bones. We conclude that maternal administration of (PhSe)2 during GD 7-12 led to increased incidences of these skeletal variations or anomalies, but did not cause externally visible malformations in rat fetuses.

Organoselenium compounds prevent hyperphosphorylation of cytoskeletal proteins induced by the neurotoxic agent diphenyl ditelluride in cerebral cortex of young rats

In this work we investigated the protective ability of the selenium compounds ebselen and diphenyl diselenide against the effect of diphenyl ditelluride on the in vitro incorporation of 32P into intermediate filament (IF) proteins from slices of cerebral cortex of 17-day-old rats. We observed that ditelluride in the concentrations of 1, 15 and 50 microM induced hyperphosphorylation of the high-salt Triton insoluble neurofilament subunits (NF-M and NF-L), glial fibrillary acidic protein (GFAP) and vimentin, without altering the immunocontent of these proteins. Concerning the selenium compounds, diselenide (1,15 and 50 microM) did not induce alteration of the in vitro phosphorylation of the IF proteins. Otherwise, ebselen induced an altered in vitro phosphorylation of the cytoskeletal proteins in a dose-dependent manner. At intermediate concentrations (15 and 30 microM) it increased the in vitro phosphorylation even though, at low (5 microM) or high (50 and 100 microM) concentrations this compound was ineffective in altering the activity of the cytoskeletal-associated phosphorylating system. In addition, 15 microM diselenide and 5 microM ebselen, presented a protective effect against the action of ditelluride, on the phosphorylation of the proteins studied. Considering that hyperphosphorylation of cytoskeletal proteins is associated with neuronal dysfunction and neurodegeneration, it is probable that the effects of ditelluride could be related to the remarkable neurotoxicity of this organic form of tellurium. Furthermore the neuroprotective action of selenium compounds against tellurium effects could be a promising route to be exploited for a possible treatment of organic tellurium poisoning.