Behavioral toxicity in the offspring of rats following maternal exposure to dichloromethane

Rats divided in four treatment groups were exposed to dichloromethane (DCM) (4500 ppm) or filtered air before and/or during gestation in order to assess the occurrence and extent of toxic effects on developing offspring. The progeny of dams exposed to DCM either prior to and/or during gestation exhibited altered rates of behavioral habituation to novel environments. No simple relationship between exposure period and behavioral outcome was observed. Each of the treatment groups showed effects as a function of age at testing and the behavioral task used. Treatment effects were detectable in offspring as early as 10 days of age and were still demonstrable in 150-day-old male rats. Treatment effects were observed in rats of both sexes in preweaning tests but were not seen in adult female rats. No effects of subacute DCM exposure were evident in growth rate, long-term food and water consumption, wheel running activity, or avoidance learning. This study, which should be viewed as preliminary, is cf interest since altered rates of habituation to novel environments were observed in the absence of overt maternal toxicity, or teratogenicity. The effects cannot be definitely attributed to a direct effect of DCM since elevated maternal carboxyhemoglobin (COHb)- or DCM-induced changes in maternal-litter interactions could have been contributing factors. The findings do suggest that the functional development of progency of DCM-exposed dams should be further investigated.     

甲胺磷对小鼠的行为致畸

实验选用多项行为检测指标及定量组织学方法,以对硫咪唑为阳性对照,研究了有机磷农药甲胺磷的小鼠行为致畸效应。结果表明小鼠围产期接触对硫咪唑和低剂量甲胺磷影响其仔代的躯体发育、反射发育及学习能力,并导致大脑皮质神经元密度增加。     

Differential gene expression in rats following subacute exposure to the anticonvulsant sodium valproate

Sodium valproate (VPA) is clinically employed as an anticonvulsant and, to a lesser extent, as a mood stabilizer. While the incidence of toxicity associated with the clinical use of valproate is low, serious hepatotoxicity makes up a significant percentage of these rare adverse effects, with fatalities occurring mainly in children receiving polypharmacy. Previous studies have highlighted the different pharmacological effects of acute valproate exposure, a combination of which are likely to underpin its observed broad-spectrum anticonvulsant efficacy. However, limited studies have been undertaken to investigate the subacute effects of this compound and how genomic effects may underlie the observed hepatotoxic effects. Investigation into the mild hepatoxicity observed in rats exposed to high doses of VPA may provide important information on the human situation. Male Sprague-Dawley rats were dosed with 500 mg/kg/day sodium valproate: after necropsy, mRNA was subjected to suppression PCR subtractive hybridization, identifying 8 up-regulated and 14 down-regulated mRNA species. The down-regulation of several mRNA species coding for enzymes involved in cellular energetics (e.g., succinate dehydrogenase, aldolase B) was of particular interest, as mitochondrial dysfunction is a key feature of valproate hepatotoxicity. In vitro studies were then undertaken to examine the dose and time dependence of these changes and also their effect on the overall energy levels within the cell. We demonstrate that, both in vivo and in vitro, valproate exposure in rats results in a significant decrease in pathways involved in cellular energy homeostasis. These changes may provide insight into the rare human hepatoxicity associated with this compound.     

Perinatal exposure to xenoestrogens affects pain in adult female rats

Estrogens have a variety of effects in addition to their action on reproductive structures, including permanent effects on the Central Nervous System (CNS). Therefore environmental chemicals with estrogenic activity (xenoestrogens) can potentially affect a number of CNS functions. In the present experiment, female rats receiving ethynylestradiol (EE) or methoxychlor (MXC) via the mothers during pregnancy (pre) or lactation (post) were tested in comparison with females born from mothers treated with OIL. The Object Recognition, Plantar and Formalin tests were carried out to evaluate the effects of these compounds on integrated functions such as memory and pain. Testosterone and estradiol plasma levels were determined by RIA. The results of the Object Recognition and Plantar tests did not differ among groups. However the groups differed in the Formalin test since flexing duration was higher in the EE- and MXC-pre groups than in the EE- and MXC-post and OIL groups. Estradiol plasma levels were higher in EE-pre than in the other groups.These results confirm the possibility that estrogen-like compounds (EE and MXC) can affect complex neural processes like pain when taken during critical stages of CNS development.     

Developmental neurotoxicity following premating maternal exposure to hexachlorobenzene in rats.

The maternal transfer of hexachlorobenzene (HCB) may place the developing organism at risk. The present study assessed the developmental neurotoxicity of HCB using a battery of behavioral tests. Two weeks prior to breeding, maternal rats were exposed via gavage to either 10 or 100 mg HCB/kg body weight. Behaviors evaluated in pups exposed maternally to HCB included the negative geotaxic reflex on postnatal day (PND) 6, 8, and 10, olfactory discrimination (PND 9-11), and the development of exploratory behavior (PND 15-20). Significant effects in these three tests indicated hyperactivity in HCB-exposed pups. No significant effects on learning (swim T-maze) or motor activity were detected in older offspring (PND 40 and 50 respectively). The acoustic startle response (ASR) revealed apparent age-related effects of maternal HCB exposure. On PND 23 pups from the high treatment group demonstrated significantly reduced ASR amplitude, whereas these same animals, tested on PND 90 (using a reflex modification design), showed elevated ASR amplitude relative to the controls. This work demonstrates that HCB is a behavioral teratogen, and suggests that human fetuses and suckling infants may be at risk from the neurotoxic effects of HCB.     

Toxicity of gestational aluminum exposure to the maternal rabbit and offspring

To assess aluminum toxicity to the Al-exposed pregnant female and her developing offspring, pregnant rabbits received 20 sc Al lactate injections (0, 25, 100, or 400 mumol Al/kg/inj) between Days 2 and 27 of gestation. Fifty-eight percent perinatal mortality resulted from the highest dose. At 2 days postpartum litters were culled to six offspring. Three of the offspring of Al-treated does were cross-fostered to a non-Al-treated doe in exchange for three of the non-Al-treated doe's offspring. Tissue Al concentrations in 0- to 2-day-old offspring positively correlated with their does' Al exposure, but were lower than Al concentrations in placental tissue or in does 5 weeks postpartum, suggesting that the placenta partially protects the fetus from Al. Offspring of 25 mumol group does gained body weight faster than controls, whereas 400 mumol group does and their offspring gained weight less rapidly than controls. The weight of milk consumed by offspring inversely correlated with their does' Al exposure. Learning a classically conditioned reflex was facilitated by lower and impaired by higher Al exposure in offspring conditioned at 7 and 11 weeks of age. Offspring receiving higher Al exposure also showed impaired memory of the learned reflex. Aluminum appears to distribute into the developing fetus where it accumulates and can produce delayed effects which may be beneficial following lower but detrimental following higher exposure concentrations.     

Silver nanoparticle exposure in pregnant rats increases gene expression of tyrosine hydroxylase and monoamine oxidase in offspring brain

Context: Maternal exposure to silver nanoparticles (AgNPs) affects neurobehavioral reflexes and spatial memory formation in offspring. Although the transmission of AgNPs into the brain has been reported, its toxic effect on dopamine metabolism in the brain of offspring has not been studied so far. Objective: The aim of the present study was to investigate the expression levels of tyrosine hydroxylase (TH) and monoamine oxidase A (MAO-A) genes in the brain of offspring exposed in utero to various concentrations of AgNPs. Materials and methods: Time mated pregnant adult rats were assigned into three groups including control, low dose of AgNPs (0.2?mg/kg) and high dose of AgNPs (2?mg/kg). AgNPs were subcutaneously (SC) injected at days of 1, 4, 7, 10, 13, 16 and 19 of pregnancy. Gene expression of TH and MAO-A was analyzed in the brain of offspring (male and female) at days of 1, 7, 14 and 21 after birth. Results: Administration of AgNPs to pregnant rats in a time- and dose-dependent manner increased the expression levels of TH in the brain of male and female pups at all tested days after birth (p?p?Discussion and conclusions: Results obtained here demonstrated that the exposure of pregnant rats to AgNPs increases the expression of genes involved in dopamine metabolism in the brain of offspring.     

Effects of maternal high-fat diet and sedentary lifestyle on susceptibility of adult offspring to ozone exposure in rats

Epidemiological and experimental data suggest that obesity exacerbates the health effects of air pollutants such as ozone (O₃). Maternal inactivity and calorically rich diets lead to offspring that show signs of obesity. Exacerbated O₃ susceptibility of offspring could thus be manifested by maternal obesity. Thirty-day-old female Long-Evans rats were fed a control (CD) or high-fat (HF) (60% calories) diet for 6 wks and then bred. GD1 rats were then housed with a running wheel (RW) or without a wheel (SED) until parturition, creating four groups of offspring: CD-SED, CD-RW, HF-SED and HF-RW. HF diet was terminated at PND 35 and all offspring were placed on CD. Body weight and %fat of dams were greatest in order; HF-SED?>?HF-RW?>?CD-SED?>?CD-RW. Adult offspring were exposed to O₃ for two consecutive days (0.8?ppm, 4?h/day). Glucose tolerance tests (GTT), ventilatory parameters (plethysmography), and bronchoalveolar fluid (BALF) cell counts and protein biomarkers were performed to assess response to O₃. Exercise and diet altered body weight and %fat of young offspring. GTT, ventilation and BALF cell counts were exacerbated by O₃ with responses markedly exacerbated in males. HF diet and O₃ led to significant exacerbation of several BALF parameters: total cell count, neutrophils and lymphocytes were increased in male HF-SED versus CD-SED. Males were hyperglycemic after O₃ exposure and exhibited exacerbated GTT responses. Ventilatory dysfunction was also exacerbated in males. Maternal exercise had minimal effects on O₃ response. The results of this exploratory study suggest a link between maternal obesity and susceptibility to O₃ in their adult offspring in a sex-specific manner.     

孕期LPS刺激对子代6周龄大鼠血管结构的影响

目的研究孕期炎症刺激剂脂多糖(lipopolysaccharides,LPS)刺激对子代大鼠6周龄时血管结构的影响。方法 12只Sprague dawley(SD)孕鼠随机分为3组:对照组(control,Con)、LPS刺激组、LPS刺激加二硫代氨基四氢呋喃(pyrrolidinedithiocarbamate,PDTC)干预组(L+P),分别在孕8~14 d腹腔注射生理盐水、LPS(0.79 mg·kg~(-1))或LPS加PDTC(100 mg·kg~(-1)),LPS于孕d 8、10、12给药;生理盐水及PDTC于d 8~14每天给药。子代出生6周测体质量;透射电镜观察血管超微结构;实时荧光定量PCR检测仔鼠胸主动脉连接蛋白(connexin,Cx)Cx37、Cx40、Cx43、Cx45的mRNA表达水平;Western blot和免疫荧光检测仔鼠胸主动脉Cx37、Cx40、Cx43、Cx45的蛋白表达水平。结果与Con组相比,LPS组子代大鼠在6周时♂♀体质量均明显增加(P<0.01);L+P组♂鼠明显低于LPS组(P<0.05),而♀鼠差异无显著性。LPS组内皮受损,内皮细胞间可见明显缝隙连接(gap junction,GJ),相对于Con组较长且多见;L+P组内皮损伤程度较LPS组稍有改善。LPS组Cx43 mRNA及蛋白表达均明显低于Con组(P<0.05),L+P组则明显高于LPS组(P<0.05);Cx37、Cx40和Cx45各组间mRNA及蛋白表达差异无统计学意义。LPS组Cx43荧光强度及荧光点数明显比Con组降低,而L+P组明显比LPS组高,各组间Cx37、Cx40和Cx45荧光强度和荧光点数并无明显差异。结论孕期LPS刺激可致子代大鼠在6周龄时出现血管结构损伤,这种损伤可能持续于新生儿期,并与其成年发生高血压密切相关。     

Cardiovascular gene expression profiles of dioxin exposure in zebrafish embryos.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a widespread environmental contaminant that causes altered heart morphology, circulatory impairment, edema, hemorrhage, and early life stage mortality in fish. TCDD toxicity is dependent, in large part, on the aryl hydrocarbon receptor (AHR), but understanding of the molecular mechanism of cardiovascular embryotoxicity remains incomplete. To identify genes potentially involved in cardiovascular effects, we constructed custom cDNA microarrays consisting of 4896 zebrafish adult heart cDNA clones and over 200 genes with known developmental, toxicological and housekeeping roles. Gene expression profiles were obtained for 3-day-old zebrafish after early embryonic exposure to either 0.5 or 5.0 nM TCDD. In all, 516 clones were significantly differentially expressed (p < 0.005) under at least one treatment condition; 123 high-priority clones were selected for further investigation. Cytochromes P450 1A and 1B1, and other members of the AHR gene battery, were strongly and dose-dependently induced by TCDD. Importantly, altered expression of cardiac sarcomere components, including cardiac troponin T2 and multiple myosin isoforms, was consistent with the hypothesis that TCDD causes dilated cardiomyopathy. Observed increases in expression levels of mitochondrial energy transfer genes also may be related to cardiomyopathy. Other TCDD-responsive genes included fatty acid and steroid metabolism enzymes, ribosomal and signal-transduction proteins, and 18 expressed sequence tags (ESTs) with no known protein homologs. As the first broad-scale study of TCDD-modulated gene expression in a non-mammalian system, this work provides an important perspective on mechanisms of TCDD toxicity.     

Behavioral and neurochemical alterations in the offspring of rats after maternal or paternal inhalation exposure to the industrial solvent 2-methoxyethanol

The industrial solvent 2-methoxyethanol (2ME) has antifertility effects in male rats at 300 ppm and is tetragenic in rats and rabbits at 50 ppm. The present research investigated if exposure of paternal or maternal animals to 25 ppm 2ME, the current U. S. permissible occupational exposure limit, would produce detectable effects in the offspring. Eighteen male young-adult Sprague-Dawley rats were exposed to 25 ppm 2ME 7 hr/day, 7 days/week for 6 weeks; they were then mated with untreated females which were allowed to deliver and rear their young. In addition, groups of 15 pregnant rats were exposed 7 hr/day on gestation days 7–13 or 14–20 and allowed to deliver and rear their young. At birth, litters were culled to 4 females and 4 males for behavioral testing of neuromotor function, activity, and simple learning ability on days 10 through 90. In addition, brains from new born and 21-day-old offspring were analyzed for neurochemical deviations from controls. No effects on paternal or maternal animals, nor on the number or weight of live offspring, were noted. Behavioral testing revealed significant differences from controls only in avoidance conditioning of offspring of mothers exposed on days 7–13. In contrast, neurochemical deviations were observed in brains from 21-day-old offspring from the paternally exposed group as well as from both maternally exposed groups; changes were numerous in the brainstem and cerebrum but were fewer in the cerebellum and midbrain. Thus it appears that both paternal and maternal inhalation of 25 ppm 2ME produces some effect which is reflected in neurochemical deviations in the offspring.     

Effects of maternal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on fetal brain growth and motor and behavioral development in offspring rats

The effects of maternal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during pregnancy on fetal brain growth and neurobehavioral development in early developmental stages were investigated using rat offspring. TCDD in corn-oil (0.1microg/kg) was orally administrated to the dams from the 9th to 19th gestational day. When TCDD effects on the fetal brain weight were analyzed on the 19th gestational day, weight ratio of the brain to the whole body, and that of the forebrain without the cerebral cortex to the whole brain were larger in the exposed group than those of the control group, suggesting premature fetal brain development. TCDD effects on motor functions were investigated using newborns in an inclined plane task. Motor development assessed by righting response on an inclination was delayed in the exposed offspring in the 8th-12th postnatal day, especially in male. Also, TCDD effects on active avoidance behavior in a shuttle box were investigated using the offspring after weaning. Latency in the active avoidance learning was longer, and locomotor activity was reduced in the exposed male offspring in the 41st-44th postnatal day. The results demonstrated that maternal TCDD exposure delayed fetal brain growth and neurodevelopment of the offspring in early stage, especially in male rats.     

Perinatal exposure to xenoestrogens impairs mammary gland differentiation and modifies milk composition in Wistar rats

The current study examined the consequences of perinatal (gestation+lactation) exposure to Bisphenol A (BPA) or diethylstilbestrol (DES) on F1 mammary gland (MG) differentiation. BPA (0, 0.7 or 64 μg/kg bw/day) or DES (6 μg/kg bw/day) was administered in the drinking water of F0 rats from gestational day 9 (GD9) until weaning. F1 females were bred, MG samples obtained on GD18 and GD21, and, during lactation, milk yield and milk protein composition were assessed. On GD18, there was a decrease in α-lactalbumin and β-casein levels that was accompanied by reduced prolactin receptor and Stat5a/b expression. On GD21, delayed histological MG differentiation was observed. β-Casein levels remained decreased on GD21 and in milk samples. Moreover, the BPA- and DES-exposed groups had an altered milk yield pattern during lactation. The long-lasting effects of perinatal exposure to low doses of xenoestrogens included delayed MG differentiation, altered milk yield and modified milk composition.     

Mixed function oxidase activities in lactating rats and their offspring following dietary exposure to polybrominated biphenyls.

Exposure of pregnant rats to diet containing 50 ppm polybrominated biphenyls (PBBs) from day 8 of gestation to day 15 postpartum caused significant increases in hepatic and extrahepatic microsomal mixed function oxidase activity. Hepatic arylhydrocarbon hydroxylase (AHH), epoxide hydratase (EH), hexobarbital hydroxylase (hex-OH), and the 2- and 4-hydroxylation of biphenyl (2-OHBP, 4-OHBP) were increased 10, 3, 3, 23, and 6-fold respectively in animals fed diet containing PBBs. The hex-OH, 2-OHBP, and 4-OHBP activities were not detectable in the S9 fraction from maternal mammary glands of control or PBB-fed rats; however, exposure to PBBs increased mammary AHH 2.5-fold and decreased EH activity 45%. Renal AHH activity was increased 7-fold but renal EH activity was unaltered by feeding PBBs. Pups from control and PBB-exposed mothers were crossfostered at birth to give offspring which received PBB exposure prenatally, postnatally (via mothers milk), or both pre- and postnatally. Each type of exposure produced increases in hepatic AHH and EH activities over those found in pups born to and raised by mothers which received no PBBs. The results demonstrate that PBBs induce hepatic and extrahepatic mixed function oxidase activity in nursing rats and that the extrahepatic effects of the mixture are different from the hepatic effects. Furthermore, PBBs were effective stimulators of hepatic enzymes in 15-day-old rats when the neonates were exposed transplacentally and/or via the mothers' milk. The results suggest potential toxic interaction between PBBs and other agents which are of importance to both mother and young.     

Effects in rats of maternal exposure to raspberry leaf and its constituents on the activity of cytochrome p450 enzymes in the offspring

The goal of our study was to determine whether maternal exposure to red raspberry leaf (RRL) and its constituents can permanently alter biotransformation of fluorogenic substrates by cytochrome P450 (CYP) in the livers of male and female offspring. Nulliparous female rats received vehicle, raspberry leaf, kaempferol, quercetin, or ellagic acid orally once breeding had been confirmed until parturition. Hepatic microsomes were prepared from animals at birth (postnatal day 1 [PND1]), weaning (PND21), PND65, and PND120 to determine the biotransformation of 8 fluorogenic substrates. The pattern of biotransformation of all but 2 of the substrates was gender specific. Maternal consumption of RRL increased biotransformation of 3 substrates by female offspring at PND120 resulting in a more masculine profile. Kaempferol and quercetin had a similar effect to RRL. These results suggest that maternal consumption of either RRL or some of its constituents leads to long-term alterations of CYP activity in female offspring.     

Fetal and offspring arrhythmia following exposure to nicotine during pregnancy

Although recent studies have demonstrated prenatal nicotine can increase cardiovascular risk in the offspring, it is unknown whether exposure to nicotine during pregnancy also may be a risk for development of arrhythmia in the offspring. In addition, in previous studies of fetal arrhythmia affected by smoking, only two patterns, bradycardia and tachycardia, were observed. The present study examined acute effects of maternal nicotine on the fetal arrhythmia in utero, and chronic influence on offspring arrhythmia at adult stage following prenatal exposure to nicotine. Nicotine was administered to pregnant ewes and rats. In the fetal sheep, intravenous nicotine not only induced changes of fetal heart rate, but also caused cardiac cycle irregularity, single and multiple dropped cardiac cycles. Although maternal nicotine had no influence on fetal blood pH, lactic acid, hemocrit, Na⁺, K⁺ levels and plasma osmolality, fetal blood PO₂ levels were significantly decreased following maternal nicotine in ewes. In offspring rats at 4–5 months after birth, prenatal exposure to nicotine significantly increased heart rate and premature ventricular contraction in restraint stress. In addition, arrhythmias induced by injection of nicotine were higher in the offspring prenatal exposure to nicotine in utero. The results provide new evidence that exposure to nicotine in pregnancy can cause fetal arrhythmia in various patterns besides tachycardia and bradycardia, the possible mechanisms for nicotine‐induced fetal arrhythmia included in utero hypoxia. Importantly, following exposure to nicotine significantly increased risk of arrhythmia in the adult offspring. The finding offers new insight for development of cardiac rhythm problems in fetal origins. Copyright © 2009 John Wiley & Sons, Ltd.