Effects of oral exposure to silver nanoparticles on the sperm of rats

It has been demonstrated that exposure to silver nanoparticles (AgNPs) can induce toxicological effects in rodents. In this study, we investigated whether sub-chronic oral exposure to different doses of polyvinil pyrrolidone (PVP)-coated AgNPs (PVP-AgNPs) (50, 100 and 200mg/kg/day) could induce harmful effects on epididymal sperm rat parameters. Sperm motility, viability and morphology were examined. Moreover, a histological evaluation of testis and epididymis was also performed. High doses of PVP-AgNPs showed higher sperm morphology abnormalities, while a progressive, but not significant effect, was observed in other sperm parameters. The current results suggest that oral sub-chronic exposure to PVP-AgNPs induces slight toxicological effects in sperm rat parameters.

Aluminum-induced pro-oxidant effects in rats: protective role of exogenous melatonin

In recent years, it has been suggested that oxidative stress is a feature of Alzheimer's disease in which aluminum (Al) could exacerbate oxidative events. The goal of the present study was to assess in rats the pro-oxidant effects induced by Al exposure, as well as the protective role of exogenous melatonin. Two groups of male rats were intraperitoneally injected with Al only or melatonin only, at doses of 5 and 10 mg/kg/day, respectively for 8 wk. During this period, a third group of animals received Al (5 mg/kg/day) and melatonin (10 mg/kg/day). At the end of the treatment period, rats were anesthesized and arterial blood was obtained. Thereafter, animals were killed and liver and brain (cortex, hippocampus and cerebellum) were removed. These tissues were processed to examine oxidative stress markers: glutathione transferase (GST), reduced glutathione (GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), thiobarbituric acid reactive substances (TBARS), as well as protein content. Samples of these tissues were also used to determine Al, Fe, Mn, Cu and Zn concentrations. The results show that Al exposure promotes oxidative stress in different neural areas, including those in which Al concentrations were not significantly increased. The biochemical changes observed in neural tissues show that Al acts as pro-oxidant, while melatonin exerts an antioxidant action in Al-treated animals. The protective effects of melatonin against cellular damage caused by Al-induced oxidative stress, together with its low toxicity, make melatonin worthy of investigation as a potential supplement to be included in the treatment of neurological disorders in which the oxidative effects must be minimized.

Interactions in developmental toxicology: effects of concurrent exposure to lead, organic mercury, and arsenic in pregnant mice

The development toxicity of lead nitrate (25 mg/kg, SC), methylmercury chloride (12.5 mg/kg, PO), and sodium arsenite (6 mg/kg, SC) was assessed in CD1 mice following administration on gestation day 10 of these chemicals separately or in their binary and ternary combinations. Cesarean sections were performed on day 18 of gestation, and fetuses were examined for malformations and variations. Three fetuses from each dam were used for whole-body analyses of Pb, Hg, and As. Maternal toxic effects were more remarkable in the group concurrently exposed to Pb, Hg, and As than in those given binary combinations of the elements. In turn, maternal toxicity was more notable in these groups than in those given separately the test compounds. With regard to developmental toxicity, the most relevant effects (decreased fetal weight, cleft palate) corresponded to the Hg-treated groups. It is in agreement with the finding that in all experimental groups the levels of Pb and As in whole fetuses were under their respective detection limits. In general terms, the present data suggests that at the current doses, the interactive effects of Pb and As on Hg-induced developmental toxicity were not greater than additive. In contrast, exposure of pregnant mice to Pb and As at doses that were practically nontoxic to dams, concurrently with organic Hg at a toxic dose, caused supra-additive interactions in maternal toxicity.

Nephrotoxicity of simultaneous exposure to mercury and uranium in comparison to individual effects of these metals in rats

Both inorganic mercury and uranium are known nephrotoxicants in mammals. In this study, the renal toxicity of a concurrent exposure to inorganic mercury and uranium was compared with the nephrotoxic effects of the individual metals in a rat model. Eight groups of rats, 10 animals per group, were subcutaneously given a single administration of mercuric chloride (HgCl2, 0.34 mg/kg and 0.68 mg/kg), uranyl acetate dihydrate (UAD, 2.5 mg/kg and 5 mg/kg), or combinations of both compounds at the same doses. A ninth group of rats received sc injections of 0.9% saline and was designated as the control group. Necrosis of proximal tubules, which was observed in all experimental groups, was the most relevant morphologic abnormality. Marked changes, which were remarkably greater than those induced by the individual elements, were noted in some urinary parameters in the groups concurrently exposed to HgCl2 and UAD. It could be an indicator of a synergistic interaction between mercury and uranium. In contrast, compared with the urinary levels found after individual administration of the highest doses of mercury and uranium, significant reductions in the urinary concentrations of these elements were noted following simultaneous exposure to both metals. At these doses, the reduction in the urinary metal excretion was also accompanied by significant decreases in the renal content of mercury and uranium. Whereas the results of some parameters pointed out a possible synergistic interaction between mercury and uranium, other measures hinted that an antagonistic interaction between these elements is also present.

Lack of protective effects of dietary silicon on aluminium-induced maternal and developmental toxicity in mice

In recent years, it has been demonstrated that oral aluminium (Al) exposure can produce growth retardation, delayed ossification and an increased incidence of foetal abnormalities in rats and mice. On the other hand, it has been also suggested that silicon may have a protective effect in limiting oral Al absorption. The aim of the present study was to assess whether dietary silicon could prevent against Al-induced maternal and developmental toxicity in mice. On gestation days 6-15, Al nitrate nonahydrate (398 mg/kg/day) was given by gavage to three groups of pregnant animals, which also received silicon in drinking water at concentrations of 0, 118 and 236 mg/l on days 7-18 of gestation. Three additional groups of pregnant mice received respectively: 270.6 mg/kg of sodium nitrate (gavage), and silicon in drinking water at 118 and 236 mg/l. Although silicon administration at 236 mg/l significantly reduced the percentage of Al-induced deaths, abortions and early deliveries, neither 118 nor 236 mg/l of silicon produced significant ameliorations on Al-induced foetotoxicity. Under the current experimental conditions dietary silicon was not effective in protecting against Al-induced developmental toxicity.

Enzymic evaluation of thiamin, riboflavin and pyridoxine status of parturient mothers and their newborn infants in a Mediterranean area of Spain

OBJECTIVE

To determine the biochemical status of thiamin, riboflavin and pyridoxine in parturient mothers and their newborn infants in a Mediterranean region.

DESIGN

Transveral study.

SETTING

St Joan University Hospital and Faculty of Medicine & Health Sciences, Universitat Rovira i Virgili, Reus, Spain.

SUBJECTS

131 healthy parturient mothers, with normal pregnancies and deliveries in St Joan University Hospital, and their newborn infants.

INTERVENTIONS

Erythrocyte haemolysates were prepared from maternal blood at delivery and infants' umbilical cord blood and used to measure micronutrient status using the transketolase, glutathione reductase and aspartate aminotransferase coenzyme stimulation tests.

RESULTS

Maternal and infant coenzyme activities were significantly correlated, but infant coenzyme status was better than maternal, with significantly higher basal and stimulated activity (P < 0.001) and significantly lower activation coefficients (P < 0.001). Inadequate thiamin, riboflavin or pyridoxine status occured in 38.2 62.6% (50-82) of the mothers and 3.1-37.4% (4 49) of the infants; 85.2% (46/54), 12.9% (4/31) and 24.1% (12/54) of infants born to mothers with biochemical deficiency of either thiamin, riboflavin or pyridoxine, respectively also had inadequate status. Maternal deficiencies in more than one vitamin further increased the risk of infant thiamin and pyridoxine deficiency. Maternal and infant riboflavin status were significantly correlated with fetal development (e.g. length at birth, P < 0.001). The incidence of thiamin deficiency in paturient mothers in Spain was the highest out of a 12-country comparison.

CONCLUSIONS

Inadequate status for each vitamin was evident in mothers and infants. Maternal status of each individual vitamin, but especially riboflavin, was affected by maternal status of the other vitamins. Infant thiamin status was the most adversely affected by maternal deficiencies in more than one vitamin. Infant riboflavin status, however, was apparently protected from adverse maternal status.

Silicon reduces aluminum accumulation in rats: relevance to the aluminum hypothesis of Alzheimer disease

In recent years, a possible relation between the aluminum and silicon levels in drinking water and the risk of Alzheimer disease (AD) has been established. It has been suggested that silicon may have a protective effect in limiting oral aluminum absorption. The present study was undertaken to examine the influence of supplementing silicon in the diet to prevent tissue aluminum retention in rats exposed to oral aluminum. Three groups of adult male rats were given by gavage 450 mg/kg/day of aluminum nitrate nonahydrate 5 days a week for 5 weeks. Concurrently, animals received silicon in the drinking water at 0 (positive control), 59, and 118 mg Si/L. A fourth group (-Al, - Si) was designated as a negative control group. At the end of the period of aluminum and silicon administration, urines were collected for 4 consecutive days, and the urinary aluminum levels were determined. The aluminum concentrations in the brain (various regions), liver, bone, spleen, and kidney were also measured. For all tissues, aluminum levels were significantly lower in the groups exposed to 59 and 118 mg Si/L than in the positive control group; significant reductions in the urinary aluminum levels of the same groups were also found. The current results corroborate that silicon effectively prevents gastrointestinal aluminum absorption, which may be of concern in protecting against the neurotoxic effects of aluminum.

Concentrations of some essential elements in the brain of aluminum-exposed rats in relation to the age of exposure

This study evaluated the influence of age on the aluminum (Al) interaction with calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) in the brain of rats. Since both Al and aging have been associated with neurobehavioral deficits in mammals, the brain was chosen to assess that influence. Male young (21 day), adult (8 months), and old (16 months) rats were given 0, 50, and 100 mg/kg per day of aluminum administered as aluminum nitrate in drinking water for 6.5 months. During that period, citric acid (0, 355 and 710 mg/kg per day) was also added to the drinking water. After 6.5 months of Al exposure, Al, Ca, Mg, Fe, Mn, Cu and Zn concentrations were determined in brain tissue as well as in a number of cerebral regions: cortex, hippocampus, striatum, cerebellum, thalamus, olfactory bulb, and rachidical bulb. While no significant age-related differences were found for Ca concentrations in the seven cerebral regions analyzed, most Mg, Fe, Mn and Zn levels were significantly higher in young than in adult and old rats. In turn, Al concentrations were mostly higher in the cerebral regions of young rats than in the same regions of adult and old rats. In contrast, Cu levels were lower in most brain regions of old animals than in those of young rats. According to the results of the present study, the age-related changes in brain Al, Ca, Mg, Fe, Mn, Cu and Zn concentrations induced by Al and aging would not suggest any influence on Al-induced neurobehavioral deficits.

The effect of age on aluminum retention in rats

The present study was designed to assess potential changes in aluminum (Al) retention during advanced age. Young (21 day old), adult (8 months), and old (16 months) rats were exposed to 0, 50, and 100 mg Al/kg/day administered as aluminum nitrate in drinking water for a period of 6.5 months. Urinary Al levels were measured after 3 and 6.5 months of Al exposure. Organ weights and tissue Al concentrations were examined at 6.5 months of Al administration. Differences in the tissue accumulation of Al with age included higher liver, kidneys, spleen, bone and testes levels in old rats than in tissues of both young or adult animals. In contrast, brain concentrations were higher in young rats. Urinary Al levels of young, adult or old Al-exposed rats showed different trends at 6.5 months of Al exposure: compared with young values adult values declined, while those of old rats tended to increase further. The current results show that tissue Al retention patterns may be significantly altered depending on the age at Al exposure. This finding may be of concern for future investigations on the potential role of Al in certain neurological disorders.

Effects of aluminium on the mineral metabolism of rats in relation to age

The present study was conducted to assess in rats the effects of chronic aluminium (Al) exposure on calcium (Ca), magnesium (Mg), manganese (Mn), copper (Cu), zinc (Zn) and iron (Fe) accumulation and urinary excretion in relation to the age of the animals. Male young (21 day old), adult (8 months), and old (16 months) rats were orally exposed to 0, 50, or 100 mg Al/kg/day for a period of 6.5 months. Urinary levels of essential elements were determined after 3 and 6.5 months of exposure, whereas tissue Ca, Mg, Mn, Cu, Zn and Fe concentrations were examined after 6.5 months of Al administration. A number of age-related changes in tissue accumulation and urinary excretion of essential elements following chronic exposure to Al were found. Concentrations of essential elements in most tissues of young Al-exposed rats were generally lower than those of adult and old rats. The highest levels of essential elements were found in old animals. Liver, testes and spleen were the tissues that showed the most remarkable increases in relation to the levels found in those tissues of young rats. Adult rats showed a pattern comparable to that of old animals for mineral metabolism in brain, whereas in bone and testes the pattern of accumulation was closer to that of young rats. While the urinary levels of Ca were generally reduced in the Al-exposed groups, no Al-associated changes were noted for Mg, Mn, Cu and Zn. In turn, after 6.5 months of Al administration Fe excretion was increased in Al-treated adult and old rats. The results of this study suggest that early stages of life cycle should be of special concern for Al-induced changes in the metabolism of essential elements.

Assessment of the protective activity of monisoamyl meso-2,3-dimercaptosuccinate against methylmercury-induced maternal and embryo/fetal toxicity in mice

The protective activity of monoisoamyl meso-2,3-dimercaptosuccinate (Mi-ADMS), a new monoester of 2,3-dimercaptosuccinic acid (DMSA), on methylmercury-induced maternal and developmental toxicity was assessed in mice. A series of four Mi-ADMS injections was given s.c. at 0.25, 6, 24, and 48 h after oral administration of 25 mg/kg of methylmercury chloride (MMC) given on day 10 of gestation. Mi-ADMS effectiveness was tested at 0, 23.8, 47.6 and 95 mg/kg. Cesarean sections were performed on gestation day 18. All live fetuses were examined for external, internal, and skeletal abnormalities. Oral MMC administration resulted in an increase in the number of resorptions, and a decrease in fetal body weight, whereas the incidence of cleft palate, micrognathia, and skeletal variations was also increased in the fetuses of the MMC-treated groups. Although significant amelioration of MMC-induced embryolethality by Mi-ADMS was not noted at any dose, MMC-induced fetotoxicity was reduced by administration of this agent at 23.8, 47.6, and 95 mg/kg. However, the intrinsic toxicity of Mi-ADMS would be a restrictive factor for the possible therapeutic use of this chelator in pregnant women exposed to organic mercury.

Effects of monoisoamyl meso-2,3-dimercaptosuccinate on arsenite-induced maternal and developmental toxicity in mice

The therapeutic efficacy of monoisoamyl meso-2,3-dimercaptosuccinate (Mi-ADMS), on arsenite-induced maternal and developmental toxicity was evaluated in the pregnant mouse. Sodium arsenite (12 mg/kg) was intraperitoneally injected into Swiss mice on day 9 of gestation, whereas Mi-ADMS was given subcutaneously at 0.25, 5, 24, and 48 hr after arsenite exposure. Amelioration by Mi-ADMS of arsenite-induced maternal and embryofetal toxicity was assessed at 23.8, 47.5, and 95 mg/kg/day. Controls received 0.9% saline with or without arsenite. Cesarean sections were performed on gestation day 18. In the positive control group (treated with arsenite only), 20.8% of the pregnant animals died, whereas 37.5% of the dams were carrying completely resorbed litters. No arsenite-induced maternal lethality was seen following treatment with Mi-ADMS at 23.8, 47.5 and 95 mg/kg/day. Also, administration of the drug at these doses significantly reduced the embryolethality, as well as the incidence of some skeletal variations provoked by sodium arsenite. Although based on these findings, Mi-ADMS might be suggested as a potential antidote to prevent the arsenite-induced maternal and developmental toxicity, due to their reduced toxicity compared to Mi-ADMS, DMSA and DMPS would probably be more advisable for pregnant women exposed to arsenite.

Relative efficacy of chelating agents on excretion and tissue distribution of manganese in mice

The effect of repeated parenteral administration of a number of structurally diverse chelating agents on the excretion and tissue distribution of manganese was assessed in mice following 4 weeks of manganese exposure. Males Swiss mice received s.c. injections of manganese(II) chloride tetrahydrate (8.9 mg Mn kg-1 body wt.) for 4 weeks (5 days per week). After the end of this exposure period, cyclohexanediaminetetraacetic acid (CDTA), ethyleneglycol-bis-(beta-aminoethylether)-N,N-tetraacetic acid (EGTA), N-(2-hydroxyethyl)ethylenediamine triacetic acid (HEDTA), isonicotinyl hydrazine (INH), L-dopa, sodium 4.5-dihydroxy-1.3-benzenedisulphonate (Tiron), p-aminosalicylic acid (PAS) or 0.9% saline (control group) were given i.p. for five consecutive days. The doses of the chelators were approximately equal to one-eighth of their respective LD50 values. Urine and faeces were daily collected for 5 days. Twenty-four hours after the final chelator injection, mice were killed and manganese concentrations were determined in various tissues. Although CDTA, EGTA and HEDTA significantly enhanced the elimination of manganese into urine, none of the chelators increased faecal excretion. Tissue concentrations of manganese were significantly reduced only by CDTA. According to these results, among the compounds tested only CDTA would mobilize effectively manganese in manganese-loaded mice.

Developmental toxicity of cyclohexanediaminetetraacetic acid (CDTA) in mice

Cyclohexanediaminetetraacetic acid (CDTA), an effective antagonist for the treatment of zinc, lead, and manganese poisoning was evaluated for maternal and developmental toxicity in pregnant Swiss mice. CDTA was given intraperitoneally on gestation days 6-15 at doses of 0, 270, 540, and 1080 mg/kg/day. On gestational day 18, the fetuses were examined for external, visceral, and skeletal malformations and variations. Treatment with CDTA at 1080 mg/kg/day resulted in a high level of maternal deaths, as well as less severe clinical signs (significant reduction in weight gain and food consumption). Increased resorptions, fetal deaths, and decreased number of live fetuses per litter were observed at 1080 mg/kg/day. Mean fetal body weights were also significantly decreased in this group. At 1080 mg/kg/day, CDTA caused external malformations, while the development of skeletal tissues was less affected. The no observable adverse effect level (NOAEL) for maternal and developmental toxicity of CDTA in mice was 540 mg/kg/day. Analyses of maternal and fetal tissues revealed only slight effects of CDTA on concentrations of calcium, magnesium, zinc, copper and iron. According to these results, the alterations in mineral metabolism should not be the major reason for CDTA-induced developmental toxicity.

Maternal and developmental toxicity of manganese in the mouse

Manganese (II) chloride tetrahydrate was investigated in Swiss mice for maternal and developmental toxicity after subcutaneous (s.c.) exposure to doses of 0, 2, 4, 8 and 16 mg/kg per day from gestation day 6 through 15. Females were sacrificed on gestation day 18, and fetuses were examined for external, visceral, and skeletal abnormalities. Maternal toxicity included significant reductions in weight gain and food consumption at 8 and 16 mg/kg/day, as well as several treatment-related deaths in the high dose-group. There were no treatment-related effects on the number of total implants, early resorptions, dead fetuses or sex ratio, whereas a significant increase in the number of late resorptions was found in the 4, 8, and 16 mg/kg/day groups. Fetotoxicity, consisting primarily of reduced fetal body weight and an increased incidence of morphological defects was also observed at 8 and 16 mg/kg/day. There were no differences between control and manganese-treated groups in the incidence of individual or total malformations. The no observable adverse effect level (NOAEL) for maternal toxicity of MnCl2 x 4H(2)0 in mice was 4 mg/kg/day, while the NOAEL for embryo/fetal toxicity was 2 mg/kg/day.

Embryotoxic and teratogenic effects of intraperitoneally administered metavanadate in mice

Metavanadate was evaluated for developmental toxicity in pregnant Swiss mice. Sodium metavanadate (NaVO3) was administered intraperitoneally on d 6-15 of gestation at doses of 0, 2, 4, or 8 mg/kg/d. On gestation d 18, all live fetuses were examined for external, visceral, and skeletal malformations and variations. Maternal toxicity was observed at 2, 4, and 8 mg/kg/d as evidenced by decreased weight gain during treatment. Increased resorptions and dead fetuses, increased percentage postimplantation loss, and reduced fetal body weight per litter were observed at 4 and 8 mg/kg/d. There were no significant increases in the type or incidence of external and skeletal anomalies, but a significant increase in the incidence of cleft palate was detected at 8 mg/kg/d. The lowest-observed-adverse-effect level (LOAEL) for maternal toxicity was 2 mg NaVO3/kg/d, while 2 mg/kg/d was also the no-observed-adverse-effect level (NOAEL) for significant developmental toxicity.

Developmental toxicity evaluation of gallium nitrate in mice

Gallium nitrate, a drug with antitumor activity, is presently undergoing clinical trials as a chemotherapeutic agent for the treatment of certain malignancies. Since there are very limited published animal toxicity data available, this study was conducted to investigate the potential adverse developmental effects of this drug. Pregnant Swiss mice were administered intraperitoneally gallium nitrate at 12.5, 25, 50, and 100 mg/kg/day on days 6, 8, 10, 12, and 14 of gestation. Monitors for maternal toxicity were body weight, food consumption and clinical signs. At sacrifice (day 18) maternal weight, liver and kidney weights, and gravid uterine weights were measured. Gestational parameters monitored were numbers of total implants, resorptions, postimplantation losses, and dead fetuses. Live fetuses were sexed, weighted, and examined for external, internal and skeletal malformations and variations. Maternal toxicity was noted in all the gallium nitrate-treated groups. Embryo/fetal toxicity was evidenced by a decrease in the number of viable implants, a reduction in fetal weight, and an increase in the number of skeletal variations (12.5, 25, 50 and 100 mg/kg). No significant increase in the incidence of malformations was observed at 12.5, 25, or 50 mg/kg. The no-observable-adverse-effect level (NOAEL) for both maternal and developmental toxicity of gallium nitrate was less than 12.5 mg/kg.

Developmental toxicity evaluation of tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate) in mice

Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate), a chelating agent used in the treatment of experimental metal poisoning, was evaluated for developmental toxicity in pregnant Swiss mice. Tiron was administered intraperitoneally on gestational days 6 through 15 at doses of 0, 750, 1500, or 3000 mg/kg/day. Cesarean sections were performed on gestation day 18. All fetuses were examined for external, visceral, and skeletal malformations and variations. Treatment with Tiron resulted in maternal toxicity at 3000 mg/kg/day as evidenced by a high number of deaths, reduced body weight during gestation and increased relative liver and kidney weights. There were no significant differences between treated and control animals on the number of total implants, dead fetuses, or sex ratio. However, embryo fetotoxicity was evidenced at 3000 mg/kg/day by a significant increase in the number of resorptions per litter, and a significant decrease in the average fetal body weight. There were no significant changes in the incidence of abnormalities (expressed as total, individual, external, visceral, or skeletal). The no observable adverse effect level (NOAEL) for maternal and developmental toxicity was 1500 mg Tiron/kg/day.