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Recently, we have provided evidence, suggesting that mice expressing the human apolipoprotein E3 (apoE3) are more prone to develop an obesity-like phenotype and a diabetic profile when subchronically fed a chlorpyrifos (CPF)-supplemented diet. The aim of the current study was to examine the underlying mechanisms through which CPF alters both insulin- and leptin-signalling pathways in an APOE-dependent manner. Both adult apoE3- and E4-targeted replacement and C57BL/6 mice were exposed to CPF at 0 or 2 mg/kg body weight/day through the diet for 8 consecutive weeks. We determined the expression of JAK2, p-JAK2, STAT3, p-STAT3, SOCS3, IRS-1, p-IRS-1, AKT, p-AKT, GSK3β, p-GSK3β, and apoE in the liver, as well as hepatic mRNA levels of pon1, pon2, and pon3. CPF markedly disrupted both leptin and insulin homeostasis, particularly in apoE3 mice. Indeed, only CPF-fed apoE3 mice exhibited an increased phosphorylation ratio of STAT3, as well as increased total SOCS3 protein levels. Similarly, the exposure to CPF drastically reduced the phosphorylation ratio of both AKT and GSK3β, especially in apoE3 mice. Overall, CPF reduced the expression of the three pon genes, principally in C57BL/6 and apoE3 mice. These results provide notable mechanistic insights on the metabolic effects of the pesticide CPF, and attest the increased vulnerability of apoE3 carriers to its metabolic-disruptor role.

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 200 mg/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. © 2016 Elsevier Inc.

Chlorpyrifos (CPF) is an organophosphorus pesticide widely and extensively used in agriculture in more than one hundred countries and found ubiquitously in the environment. The present study was aimed at providing a better understanding of the obesogenic potential of CPF and its metabolites, as well as to evaluate their effects on the adipocyte differentiation process. For it, during the initial differentiation process, 3T3-L1 mouse preadipocytes were exposed to different concentrations of CPF, CPF-oxon (CPO), or 3,5,6-trichloropyridinol (TCP), which did not affect cell survival. Results showed how CPF and, to a lesser extent, its metabolite TCP, had a positive metabolic influence over the adipogenic process by fostering an increase in the number of differentiated 3T3-L1 preadipocytes, and by enhancing the capacity to store lipid droplets. These processes seem to occur through the upregulation of the transcription factors CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ), which are related to a significant higher expression of the fatty acid-binding protein 4 (FABP4) adipokine. Based on this finding, CPF exposure could be one of the many factors that contributes to the worldwide increase in the incidence of obesity. However, additional investigations are clearly needed.

The aim was to determine the levels and activities of the oxidative stress markers in erythrocytes, plasma, and urine after a flat cyclist stage. Eight voluntary male professional trained-cyclists participated in the study. Exercise significantly increased erythrocyte, leukocyte, platelet, and reticulocyte counts. The exercise induced significant increases in the erythrocyte activities of catalase (19.8%) and glutathione reductase (19.2%), while glutathione peroxidase activity decreased significantly (29.3%). Erythrocyte GSSG concentration was significantly increased after exercise (21.4%), whereas GSH was significantly diminished (20.4%). Erythrocyte malondialdehyde levels evidenced a significant decrease 3 h after finishing the stage (44.3%). Plasma malondialdehyde, GSH and GSSG levels significantly decreased after 3 hr recovery (26.8%, 48.6%, and 31.1%, respectively). The exercise significantly increased the F2-isoprostane concentration in urine from 359 ± 71 pg/mg creatinine to 686 ± 139 pg/mg creatinine. In conclusion, a flat cycling stage induced changes in oxidative stress markers in erythrocytes, plasma, and urine of professional cyclists. Urine F2-isoprostane is a more useful biomarker for assessing the effects of acute exercise than the traditional malondialdehyde measurement.

On gestation day (GD) 6 to GD 19, pregnant Sprague Dawley rats were orally exposed to 0, 0.5, 1, and 2 mg/kg/day to one of the most prevalent polybrominated diphenyl ethers congeners found in humans, 2,2',4,4',5-pentaBDE (BDE-99). All dams were euthanized on GD 20, and live fetuses were evaluated for sex, body weight, and external, internal, and skeletal malformations and developmental variations. The liver from one fetus of each litter was excised for the evaluation of oxidative stress markers and the messenger RNA expression of multiple cytochrome P450 (CYP) isoforms. Exposure to BDE-99 during the gestational period produced delayed ossification, slight hypertrophy of the heart, and enlargement of the liver in fetuses. A transplacental effect of BDE-99, evidenced by the activation of nuclear hormones receptors that induce the upregulation of CYP1A1, CYP1A2, CYP2B1, and CYP3A2 isoforms, was also found in fetal liver. These isoforms are correlated with the activity level of the enzyme catalase and the levels of thiobarbituric acid reactive substances. However, teratogenic effects from BDE-99 exposure were not observed. Clear signs of embryo/fetal toxicity, due to a possible hormonal disruption, were evidenced by a large increase in the CYP system and the production of reactive oxygen species in fetal liver.

Polybrominated diphenyl ethers (PBDEs) are used as flame retardants. Although developmental neurotoxicity of PBDEs has been already investigated, little is still known about their potential neurotoxic effects in adulthood. In this study, we assessed the oxidative damage in brain sections and the possible behavioral effects induced by exposure to 2,2',4,4',5-pentabromodiphenyl ether (BDE-99). Adult male rats (10/group) received BDE-99 by gavage at single doses of 0, 0.6 or 1.2mg/kg/body weight. Forty-five days after exposure, the following behavioral tests were conducted: open-field activity, passive avoidance and Morris water maze. Moreover, cortex, hippocampus and cerebellum were processed to examine the following oxidative stress (OS) markers: reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT) and thiobarbituric acid reactive substances (TBARS). In cerebellum, BDE-99 significantly decreased SOD, CAT and GR activities at the highest BDE-99 dose. A decrease in CAT and SOD activities was also observed in cortex and hippocampus, respectively. In the behavioral tests, no BDE-99 effects were observed, while histopathological examination of the brain regions was normal. The current results show that the brain antioxidant capacity is affected by BDE-99 exposure, mainly in cerebellum. Oxidative damage could be a mechanism for BDE-99 neurotoxicity in adult rats.

Oral subchronic exposure to silver nanoparticles in rats DOI: 10.1016/j.fct.2016.04.010 Because of their extremely small size, silver nanoparticles (AgNPs) show unique physical and chemical properties, with specific biological effects, which make them particularly attractive for being used in a number of consumer applications. However, these properties also influence the potential toxicity of AgNPs. In this study, we assessed the potential toxic effects of an in vivo oral sub-chronic exposure to polyvinyl pyrrolidone coated AgNPs (PVP-AgNPs) in adult male rats. We also assessed if oral PVP-AgNPs exposure could alter the levels of various metals (Fe, Mg, Zn and Cu) in tissues. Rats were orally given 0, 50, 100 and 200 mg/kg/day of PVP-AgNPs. Silver (Ag) accumulation in tissues, Ag excretion, biochemical and hematological parameters, metal levels, as well as histopathological changes and subcellular distribution following PVP-AgNPs exposure, were also investigated. After 90 days of treatment, AgNPs were found within hepatic and ileum cells. The major tissue concentration of Ag was found in ileum of treated animals. However, all tissues of PVP-AgNPs-exposed animals showed increased levels of Ag in comparison with those of rats in the control group. No harmful effects in liver and kidney, as well as in biochemical markers were noted at any treatment dose. In addition, no hematological or histopathological changes were found in treated animals. However, significant differences in Cu and Zn levels were found in thymus and brain of PVP-AgNPs-treated rats.

The present study was aimed at providing a better understanding of the influence of silver nanoparticles (AgNPs) on the p53 tumor suppressor protein. Cell line A549 was exposed to a range of concentrations of AgNPs, and a time course (up to 72 h) of cell viability was determined. We also determined the time course of gene and protein expression of p53, p21, murine double minute 2 (MDM2) and caspase-3. The expression of all of these proteins was also determined after daily exposure of the cells to 10 µg/mL of AgNPs for 7 days, or after discontinuous exposure by treating the cells every 3 days, for 15 or 30 days. Moreover, epigenetic changes in the acetylation of the histone H3 protein and in global DNA methylation patterns were determined after 72 h of exposure. Results showed that daily exposure to low doses of AgNPs, or a single exposure to high concentrations for 72 h, decreased gene and protein expression of p53, p21, MDM2 and caspase-3 in A549 cells. In contrast, a discontinuous exposure to low doses or a single exposure to low concentrations for 72 h increased the levels of the active forms of p53 and caspase-3, as well as the p21 and MDM2 protein levels. In addition, exposure to high concentrations of AgNPs for 72 h induced higher levels of global DNA methylation and global histone H3 deacetylation in A549 cells. These results provide new information on the toxic action of AgNPs.

The pro-oxidant activity of uranium (U) was assessed in kidney and testes of male rats, tissues in which toxic effects of this metal are well established. Eight groups of Sprague-Dawley rats received uranyl acetate dihydrate (UAD) in the drinking water at 0, 10, 20, and 40 mg/kg day for 3 months. Rats in four groups were concurrently subjected to restraint during 2 h/day throughout the study. Histopathological examination of the kidneys revealed an angiomatose transformation in U-treated animals. In kidney, thiobarbituric acid-reactive substances (TBARS) levels and oxidized glutathione (GSSG) activity were correlated with U exposure. The superoxide dismutase (SOD) activity was significantly enhanced in both kidney and testis. Oral UAD administration induced a decrease of glutathione reductase (GR) and reduced glutathione (GSH) in the male reproductive tract. The results of this study suggest that graded doses of U elicit depletion of the antioxidant defence system of the rat and induce oxidative stress in testes and kidneys. Although at the current U doses, restraint stress scarcely showed additional adverse effects, its potential influence should not be underrated.

The influence of restraint stress on uranium (U)-induced behavioral effects was assessed in adult male rats. Eight groups of animals received uranyl acetate dihydrate (UAD) in the drinking water at doses of 0, 10, 20 and 40 mg/kg/day during 3 months. Rats in four groups were concurrently subjected to restraint during 2 h per day throughout the study. At the end of the period of uranium exposure, the following behavioral tests were carried out: open-field activity, passive avoidance and Morris water maze. Uranium concentrations in brain were also determined. At 10 and 20 mg/kg/day of UAD restraint significantly affected the total distance traveled in the open-field during the first and third periods tested, respectively, while no significant differences between groups were observed on the passive avoidance test. In the Morris water maze test, the influence of restraint was only significant on the latency time measured on Day 3 in rats exposed at 10 mg/kg/day. Restraint stress did not affect significantly the uranium levels in brain of rats. Although the results of the present study scarcely show uranium-induced behavioral effects at the oral doses of UAD here administered, these effects, as well as the slight influence of restraint stress noted in some tests should not be underrated.

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.

Background Since deferiprone can be an effective chelating agent for the treatment of aluminum (Al) overload, in the present study we investigated whether this chelator could protect against Al-induced maternal and developmental toxicity in mice. Methods A single oral dose of Al nitrate nonahydrate (1,327 mg/kg) was given on gestation day 12, the most sensitive time for Al-induced maternal and developmental toxic effects in mice. At 2, 24, 48, and 72 hr thereafter, deferiprone was given by gavage at 0 and 24 mg/kg. Cesarean sections were performed on day 18 of gestation and fetuses were examined for malformations and variations. Results Aluminum-induced maternal toxicity was evidenced by significant reductions in body weight gain, corrected body weight change, and food consumption. Developmental toxicity was evidenced by a significant decrease in fetal weight per litter and an increase in the total number of fetuses and litters showing bone retardation. No beneficial effects of deferiprone on these adverse effects could be observed. By contrast, a more pronounced decrease in maternal weight gain and corrected body weight change, as well as a higher number of litters with fetuses showing skeletal variations was noted in the group exposed to Al nitrate and treated with deferiprone at 24 mg/kg. Conclusions According to the current results, deferiprone would not be effective to prevent Al-induced maternal and embryo/fetal toxicity in mice.

The aim of this study was to assess in mice the potential influence of maternal restraint stress and aluminum (Al) on the postnatal development and behavior of the offspring. On Days 6–15 of gestation, two groups of pregnant mice received intraperitoneal injections of AlCl3 at 75 mg/kg/day. One of these groups was also subjected to restraint for 2 h per day during the same days of gestation. Control groups included restrained and unrestrained pregnant mice nonexposed to Al. No significant differences between the groups were noted on maternal food consumption, total body weight change, maternal body weight at termination, or length of gestation. All the animals were allowed to deliver and wean their offspring. The pups were evaluated for physical development and neuromotor maturation. Moreover, open-field activity, motor resistance and coordination, and passive avoidance were also determined on postnatal Days 22, 30, and 60, respectively. The results show that, although an influence of maternal restraint on Al-induced postnatal developmental effects could be observed, the behavior of the offspring was not significantly affected.

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.

Recent studies have shown that oral vanadate (V5+) administration results in behavioral toxicity in rats. The chelating agent Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate) is an effective antidote in the removal of vanadium from vanadium-loaded rats. In this study, the protective activity of Tiron on vanadate-induced behavioral toxicity was evaluated in adult rats. Intraperitoneal treatment with Tiron at 235 or 470 mg/kg was initiated after 6 wk of oral sodium metavanadate administration (16 mg/kg/d) and continued for 2 wk. Although vanadate exposure did not result in a significant reduction in the general activity of the animals in an open field, a lower active avoidance acquisition could be observed. However, the vanadate-induced behavioral deficit was reverted by Tiron administration at 470 mg/kg. The present results suggest that Tiron may protect, at least in part, against metavanadate-induced behavioral toxicity.

The maternal and developmental toxicity of combined exposure to restraint stress and caffeine was assessed in mice. On Day 9 of gestation, six groups of pregnant mice were treated (p.o.) with a single dose of 30, 60, or 120 mg/kg of caffeine. Immediately after caffeine administration, three of these groups were subjected to restraint for 14 hr. Control groups included unrestrained and restrained pregnant mice not exposed to caffeine. An additional group of animals (unrestrained and not exposed to caffeine) was deprived of food for 14 hr. A two-way (caffeine dose x restraint) analysis of variance revealed an overall effect (reduction) of restraint and caffeine exposure on maternal body weight gain and food consumption on gestation Days 9-11. Significant reductions were also observed in body weight at termination and corrected body weight change of dams concurrently exposed to 120 mg/kg of caffeine and restraint. By contrast, no significant effects of caffeine, restraint, or caffeine plus restraint on embryo/fetal development were noted. The doses of caffeine administered here are much higher than those usually consumed by the general population. Under the current experimental conditions, caffeine alone or combined with restraint stress was not embryotoxic or teratogenic in mice.

SANCHEZ, D. J., M. T. COLOMINA AND J. L. DOMINGO. Effects of vanadium on activity and learning in rats. PHYSIOL BEHAV 63(3) 345–350, 1998.—The effects of vanadate administration on activity and learning were assessed in rats. Four groups of adult male rats were given by gavage 0, 4.1, 8.2, and 16.4 mg/kg/day of sodium metavanadate for eight consecutive weeks. Three weeks after the cessation of the treatment, general motor activity of all animals was measured in an open-field. Rats were also tested for two-way shock avoidance learning in an automatic reflex conditioner. At the end of the testing period, rats were killed and vanadium concentration was determined in a number of tissues. Vanadium exposure caused an observable but not significant effect on body weight gain, while a persistent presence of vanadium was observed in all tissues measured. The results of the behavioral testing show that oral vanadate administration resulted in significant reductions in both general activity and learning.

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 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.

Exposure of pregnant women to polybrominated diphenyl ethers (PBDEs) may mean serious health risks. The main goal of the present study was to examine the neurobehavioral changes in rat offspring that were perinatally exposed to one of the most prevalent PBDEs congeners found in humans, 2,2',4,4',5-pentaBDE (BDE-99). Rat dams were exposed to 0, 1 and 2mg/kg/day of BDE-99 from gestation day 6 to post-natal day 21. When pups were weaning, cortex and hippocampal gene expressions of brain-derived neurotrophic factor (BDNF) of the different isoforms of the thyroid hormone (TH) receptors (TRs) were evaluated. Serum TH levels were also determined. The remaining pups were assessed by neurobehavioral testing for learning and memory function. The results showed that maternal transference of BDE-99 produced a delay in the spatial learning task in the water maze test. Moreover, the open-field test revealed a significant dose-response anxiolytic effect. It was also found that the serum levels of triiodothyronine (T3), tetraiiodothyronine (T4) and free-T4 (FT4) decreased. Although no effect on the gene expression of the different isoforms of TRs was observed, the expression of the TH-mediated gene BDNF was down-regulated in the hippocampus. These results indicate a clear signal disruption of TH and reinforce previous studies in which neurotoxic effects of PBDEs in animal research were observed at levels comparable to those found in humans.

The embryotoxic and teratogenic effects of methylmercury in experimental animals have been established by several investigators. The protective activity of 2,3-dimercaptopropanol (BAL) and sodium 2,3-dimercaptopropane-1-sulfonate (DMPS, a chelator used in the treatment of inorganic and organic mercury) on methylmercury chloride (MMC)-induced maternal and developmental toxicity in mice has been evaluated in the present study. BAL and DMPS were administered subcutaneously or by gavage to pregnant mice immediately after a single oral administration of 30 mg MMC/kg given on day 10 of gestation and at 24, 48, and 72 h thereafter. Amelioration by BAL and DMPS of MMC embryo/fetotoxicity was assessed at 15, 30, and 60 mg/kg/day and at 90, 180, and 350 mg/kg/day, respectively. Treatment with BAL did not ameliorate the maternal toxicity or the developmental toxicity of MMC observed in the mouse. In contrast, DMPS at 90, 180, and 360 mg/kg/day significantly reduced the maternal lethality of MMC, whereas treatment with 180 and 360 mg DMPS/kg/day showed significant protective activity against MMC-induced embryotoxicity and teratogenicity. Based on the present findings, DMPS might be a useful chelator against the maternal and developmental toxicity induced by methylmercury.

The protective role of exogenous melatonin on U-induced nephrotoxicity was investigated in rats. Animals were given single doses of uranyl acetate dihydrate (UAD) at 5 mg/kg (subcutaneous), melatonin at 10 or 20 mg/kg (intraperitoneal), and UAD (5 mg/kg) plus melatonin (10 or 20 mg/kg), or vehicle (control group). In comparison with the UAD-treated group only, significant beneficial changes were noted in some urinary and serum parameters of rats concurrently exposed to UAD and melatonin. The increase of U excretion after UAD administration was accompanied by a significant reduction in the renal content of U when melatonin was given at a dose of 20 mg/kg. Melatonin also reduced the severity of the U-induced histological alterations in kidney. In renal tissue, the activity of the superoxide dismutase (SOD) and the thiobarbituric acid reactive substances (TBARS) levels increased significantly as a result of UAD exposure. Following UAD administration, oxidative stress markers in erythrocytes showed a reduction in SOD activity and an increase in TBARS levels, which were significantly restored by melatonin administration. In plasma, reduced glutathione (GSH) and its oxidized form (GSSG) were also altered in UAD-exposed rats. However, only the GSSG/GSH ratio was restored to control levels after melatonin treatment. Oxidative damage was observed in kidneys. Melatonin administration partially restored these adverse effects. It is concluded that melatonin offers some benefit as a potential agent to treat acute U-induced nephrotoxicity.

Metal toxicity may be associated with increased rates of reactive oxygen species (ROS) generation within the central nervous system (CNS). Although the kidney is the main target organ for uranium (U) toxicity, this metal can also accumulate in brain. In this study, we investigated the modifications on endogenous antioxidant capacity and oxidative damage in several areas of the brain of U-exposed rats. Eight groups of adult male rats received uranyl acetate dihydrate (UAD) in the drinking water at 0, 10, 20, and 40 mg/kg/day for 3 months. Animals in four groups were concurrently subjected to restraint stress during 2h/day throughout the study. At the end of the experimental period, cortex, hippocampus and cerebellum were removed and processed to examine the following stress markers: reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), thiobarbituric acid reactive substances (TBARS), as well as U concentrations. The results show that U significantly accumulated in hippocampus, cerebellum and cortex after 3 months of exposure. Moreover, UAD exposure promoted oxidative stress in these cerebral tissues. In cortex and cerebellum, TBARS levels were positively correlated with the U content, while in cerebellum GSSG and GSH levels were positively and negatively correlated, respectively, with U concentrations. In hippocampus, CAT and SOD activities were positively correlated with U concentration. The present results suggest that chronic oral exposure to UAD can cause progressive perturbations on physiological brain levels of oxidative stress markers. Although at the current UAD doses restraint scarcely showed additional adverse effects, its potential influence should not be underrated.

The influence of stress on postnatal development and behavior was assessed in the offspring of male rats exposed to uranium (U). Eight groups of adult animals received uranyl acetate dihydrate (UAD) in the drinking water at doses of 0, 10, 20 and 40 mg/kg/day during 3 months. One half of rats in each group were concurrently subjected to restraint stress during 2 h per day throughout the study. At the end of the experimental period, male rats were mated with untreated females (1:2). On gestation day 14, one half of pregnant rats were euthanized in order to evaluate maternal toxicity and gestational parameters. The remaining dams were allowed to deliver and wean their offspring. Pups were evaluated for physical development, neuromotor maturation, as well as for behavioral effects. Restraint significantly increased the gravid uterine weight at 40 mg/kg/day. However, no significant interactions between restraint and U could be established in the remaining parameters of maternal toxicity. In the offspring, no remarkable effects of U, restraint or their combination were noted on developmental landmarks, or in the passive avoidance and water maze test. It is concluded that at the current U doses, restraint stress did not enhance the few uranium-induced physical, neuromotor and behavioral changes in the offspring of UAD-exposed male rats.

The effects of stress on the potential reproductive toxicity of long-term exposure to uranyl acetate dihydrate (UAD) were assessed in adult male rats. Six groups of animals were given UAD at 10, 20, and 40 mg/kg/day in the drinking water during 3 months. Animals in three of these groups were also subjected to restraint for 2 h/day during the same period. Control groups included restrained and unrestrained male rats not exposed to UAD. To evaluate the fertility, male rats were mated with untreated females for 2 weeks. Although body weight was not affected by uranium at any dose, there was a significant (not dose-related) decrease in the pregnancy rate. Moreover, spermatid number/testis was significantly decreased by uranium administration. Histopathological examination of the testes in rats killed after 3 months of treatment revealed few differences in the tubule and interstitial alterations (focal atrophy, binucleated cells) between control and uranium-exposed animals. The results of this investigation show that at the current UAD doses, restraint stress did not enhance the uranium-induced adverse effects on reproduction in male rats.

The influence of restraint stress on uranium (U)-induced behavioral effects was assessed in adult male rats. Eight groups of animals received uranyl acetate dihydrate (UAD) in the drinking water at doses of 0, 10, 20 and 40 mg/kg/day during 3 months. Rats in four groups were concurrently subjected to restraint during 2 h per day throughout the study. At the end of the period of uranium exposure, the following behavioral tests were carried out: open-field activity, passive avoidance and Morris water maze. Uranium concentrations in brain were also determined. At 10 and 20 mg/kg/day of UAD restraint significantly affected the total distance traveled in the open-field during the first and third periods tested, respectively, while no significant differences between groups were observed on the passive avoidance test. In the Morris water maze test, the influence of restraint was only significant on the latency time measured on Day 3 in rats exposed at 10 mg/kg/day. Restraint stress did not affect significantly the uranium levels in brain of rats. Although the results of the present study scarcely show uranium-induced behavioral effects at the oral doses of UAD here administered, these effects, as well as the slight influence of restraint stress noted in some tests should not be underrated.

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.

Background Stress can result in an increased use of substances such as caffeine and aspirin. The effect of maternal stress on concurrent exposure to caffeine and aspirin on prenatal development was assessed in mice. Methods On gestational day 9, mice were assigned to three treatment groups orally exposed to caffeine (30 mg/kg), aspirin (250 mg/kg), or a combination of caffeine (30 mg/kg) and aspirin (250 mg/kg). Three additional groups of pregnant animals received similar caffeine and aspirin doses and were immediately subjected to restraint for 14 hr. Control groups included unrestrained and restrained pregnant mice not exposed to caffeine or aspirin. All dams were euthanized on gestational day 18. Live fetuses were evaluated for sex, body weight, and external, internal, and skeletal malformations and variations. Results A single oral dose of caffeine or aspirin did not cause significant maternal toxicity. However, coadministration of these drugs with restraint produced some adverse maternal effects (i.e., reduction in maternal weight gain and food consumption on gestational days 9–11). In relation to embryo/fetal toxicity, the incidence of some skeletal defects was significantly increased after exposure to caffeine, aspirin, or maternal restraint, and their binary and ternary combinations. Conclusions Although caffeine and aspirin were given in a single dose in this study, the results suggest that prenatal stress could slightly exacerbate the maternal and developmental toxicity of the combination of these drugs in mice. Teratology 63:144–151, 2001. © 2001 Wiley-Liss, Inc.

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.

The present study was conducted to assess in rats the effects of oral aluminum (Al) exposure on calcium (Ca), magnesium (Mg), manganese (Mn), copper (Cu), zinc (Zn), and iron (Fe) accumulation and urinary excretion. Three groups of plug-positive Sprague-Dawley (SD) rats were given by gavage 0, 200, and 400 mg/kg/d of Al(OH)3 on gestational days 1–20. Three groups of nonpregnant female SD rats of the same age received Al(OH)3 by gavage at the same doses for 20 consecutive days. At the end of the treatment period, 24-h urine samples were collected for analysis of Al and essential elements. Subsequently, all animals were sacrificed and samples of liver, bone, spleen, kidneys, and brain were removed for metal analyses. With some exceptions, the urinary amounts of Al, Mn, and Cu excreted by pregnant animals as well as the urinary levels of Al excreted by nonpregnant rats were higher in the Al-treated groups than in the respective control groups. Although higher Al levels were found in the liver of pregnant rats, the concentrations of Al in the brain of these animals were lower than those found in the same tissues of nonpregnant rats. With regard to the essential elements, tissue accumulation was most affected in pregnant than in nonpregnant animals. In pregnant rats, the hepatic and renal concentrations of Ca, Mg, Mn, Cu, Zn, and Fe, as well as the levels of Ca in bone, and the concentrations of Cu in brain were significantly higher in the Al-exposed groups than in the control group. According to the current results, oral Al exposure during pregnancy can produce significant changes in the tissue distribution of a number of essential elements.

The influence of restraint stress on potential aluminum (Al)-induced behavioral changes was assessed in CD-1 mice. Three groups of adult mice were given 0, 300 and 600 mg Al/kg body weight per day in drinking water for 2 weeks. One-half of the animals in each group were concurrently subjected to restraint stress during 1 h per day throughout the study. After cessation of treatment, open-field activity, active avoidance learning, and motor resistance and coordination of the animals were evaluated. At the end of the behavioral testing period, mice were killed and Al concentrations were determined in a number of tissues. There were no remarkable effects of Al, restraint stress or their combined administration on either open-field activity or on the number of avoidances in an automatic reflex conditioner. However, a lower motor resistance and coordination in a rotarod were observed following exposure to Al at 600 mg/kg/day, restraint alone or concurrent administration of Al (300 and 600 mg/kg/day) plus restraint stress. The levels of Al in whole brain and cerebellum were significantly enhanced in mice exposed to Al plus restraint. Although the present results scarcely show Al-induced neurobehavioral effects, the influence of restraint stress on Al levels in whole brain and cerebellum can be the basis for further studies on the potential role of this element in certain neurological disorders.

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.

The possible use of vanadium compounds in the treatment of diabetic patients is now being evaluated. However, previously to establish the optimal maximum dose for diabetes therapy, it should be taken into account that vanadium is a highly toxic element to man and animals. The toxic effects of vanadium are here reviewed. The tissue vanadium accumulation, which would mean an additional risk of toxicity following prolonged vanadium administration is also discussed. Recently, it has been shown that coadministration of vanadate and TIRON, an effective chelator in the treatment of vanadium intoxication, reduced the tissue accumulation of this element, decreasing the possibility of toxic side effects derived from chronic vanadium administration without diminishing the hypoglycemic effect of vanadium. However, previously to assess the effectiveness of this treatment in diabetic patients, a critical reevaluation of the antidiabetic action of vanadium and its potential toxicity is clearly needed.

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-(β-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 LD 50 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.

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.

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.

Although the disruption of thyroid hormone (TH) signaling can largely explain the neurotoxic effects of polybrominated diphenyl ethers (PBDEs), there are still many unknowns about how this interference occurs. In this study, we expose a primary culture of rat cerebellar granule neurons (CGNs) to a 25μM concentration of one of the most prevalent PBDE congeners in humans, 2,2',4,4',5-pentaBDE (BDE-99). The main goal was to investigate the time course of BDE-99 toxicity in relation to the disruption of thyroid receptor (TR) function over 24h. In a first stage, we found that BDE-99 directly down-regulated the transcription of the isoforms TR-alpha1 and TR-alpha2, which may be a consequence of a hypothetical state that mimics hyperthyroidism. In a later stage, BDE-99 disrupted the expression of triiodothyronine (T3)-responsive genes, possibly as an effect of its metabolism. A down-regulation of the expression of the T3-mediated neurotrophin brain-derived neurotrophic factor (BDNF) and the anti-apoptotic Bcl-2 protein was also observed. Down-regulation of these two proteins was correlated with an increase in the production of reactive oxygen species (ROS). It was also found that expression of the TR-beta1 isoform, which is normally transcriptionally repressed by T3 in CGNs, was up-regulated. This up-regulation could compensate the down-regulation of the TR-alpha1 isoform, and thus slow down cell death. The dually disruptive action of BDE-99 might provide a better understanding of the potentially neurotoxic mechanism of PBDEs.