Maternal exposure to environmental tobacco smoke,GSTM1/T1 polymorphisms and oxidative stress

Environmental tobacco smoking (ETS) is known to be associated with adverse pregnancy outcomes. The purpose of this study was to investigate the relationship between maternal exposure to ETS and oxidative stress for neonates, as well as the effect of maternal genetic polymorphisms, glutathione-S-transferase M1 (GSTM1) and GSTT1, on this relationship.We used the radioimmunoassay to measure the urinary concentration of cotinine in 266 pregnant women who denied smoking cigarettes during pregnancy and in their singleton babies. In addition, the urinary concentration of malondialdehyde (MDA) and 8-hydroxy-2-deoxyguanosine (8-OH-dG) were assessed using high-performance liquid chromatography and enzyme-linked immunosorbent assay, respectively. We also extracted DNA from whole blood obtained from the mothers and then conducted polymerase chain reaction on the samples to determine the GSTM1 and GSTT1 genotypes.The maternal cotinine concentration was found to be significantly associated with the fetal cotinine concentration, particularly for mothers whose urine cotinine concentrations were above 120 μg/g cr (p < 0.01). The fetal urine cotinine concentration was also found to be significantly associated with the fetal urine MDA concentration (p < 0.01). When the null type maternal GSTM1 or the wild type GSTT1 was present, the maternal oxidative stress level increased significantly as the maternal continine concentration increased (MDA: p < 0.01; 8-OH-dG: p < 0.01). No significant relationships were found between maternal cotinine and fetal oxidative stress markers, however, the fetal MDA levels increased significantly as fetal cotinine levels increased.These results suggest that the maternal exposure to ETS affects the fetal urine cotinine concentration and induces production of maternal oxidative stress. In addition, maternal genetic polymorphisms of GSTM1 and GSTT1 may modify the oxidative stress by maternal exposure to ETS.     

Differential effects of chronic ethanol exposure on cytochrome P450 2E1 and the hypothalamic–pituitary–adrenal axis in the maternal–fetal unit of the guinea pig

BackgroundEthanol neurobehavioural teratogenicity is a leading cause of developmental mental deficiency, in which the hippocampus is a target site of injury. The multi-faceted mechanism of ethanol teratogenicity is not completely understood. This study tested the hypothesis that chronic ethanol exposure (CEE), via chronic maternal ethanol administration, increases cytochrome P450 2E1 (CYP2E1) expression and alters hypothalamic–pituitary–adrenal (HPA) axis activity in the maternal–fetal unit during the third-trimester-equivalent of gestation.MethodsPregnant Dunkin–Hartley-strain guinea pigs received daily oral administration of ethanol (4 g ethanol/kg maternal body weight) or isocaloric-sucrose/pair-feeding (control) throughout gestation (term, about gestational day (GD) 68). On GD 45, 55 and 65, pregnant animals were euthanized 2 h after the last daily dose. Maternal and fetal body weights and fetal hippocampal brain weight were determined. Maternal and fetal samples were collected for the determination of liver CYP2E1 enzymatic activity and plasma free cortisol and ACTH concentrations.ResultsCEE, with maternal blood ethanol concentration of 108–124 mg/dl at 2 h after the last dose, decreased fetal hippocampal weight only at GD 65 and had no effect on fetal body weight compared with control. CYP2E1 activity increased with gestational age in the fetal liver microsomal and mitochondrial fractions. CEE increased CYP2E1 activity in the microsomal and mitochondrial fractions of maternal liver at the three gestational ages and in both hepatic subcellular fractions of the GD 65 fetus compared with control. There was a gestational-age-dependent increase in maternal and fetal plasma free cortisol concentrations, but no effect of CEE compared with control. Maternal and fetal plasma ACTH concentrations were unaffected by CEE compared with control, and were virtually unchanged during the third-trimester-equivalent that was studied.ConclusionThese data demonstrate that, in the pregnant guinea pig, this CEE regimen increases liver CYP2E1 activity, without affecting HPA axis function, in the maternal–fetal unit during near-term gestation. The CEE-induced increase in liver CYP2E1 activity and potential oxidative stress in the maternal–fetal unit may play a role in the pathogenesis of ethanol teratogenicity.     

Developmental toxicity assessment of tanezumab,an anti-nerve growth factor monoclonal antibody,in cynomolgus monkeys (Macaca fascicularis)

Two intravenous studies with tanezumab, an anti-nerve growth factor monoclonal antibody, were conducted in pregnant cynomolgus monkeys to assess potential effects on pregnancy and pre- and postnatal development. Study 1 evaluated infants up to 12 months of age following weekly maternal dosing (0, 0.5, 4 or 30 mg/kg; 18 per group) from gestation day (GD) 20 through parturition. Study 2 evaluated infants 2 months postnatally following weekly maternal dosing (0, 0.5 or 30 mg/kg; 20–21 per group) from GD 20 through 48. In the absence of maternal toxicity, tanezumab increased stillbirth and post-birth infant mortality/morbidity, decreased infant growth and resulted in microscopic changes in the peripheral sympathetic and sensory nervous system of the infants at all doses. Decreased primary antibody responses and increased incidences in skin changes in infants were also observed. The no-observed-adverse-effect-level for maternal toxicity was 30 mg/kg and <0.5 mg/kg for developmental toxicity.     

Effects of maternal exposure to di-n-butyl phthalate during pregnancy and breastfeeding on ovarian development and function of F1 female rats

This study aimed to investigate the effects of maternal exposure to di-n-butyl phthalate (DBP) during pregnancy and breastfeeding on F1 ovarian development and function. A rat model of maternal exposure to DBP during pregnancy and breastfeeding was established by gavage feeding female Sprague Dawley rats with 0, 10, 100, or 600 mg/kg/day DBP from gestational day (GD) 12 to postnatal day (PND) 21. F1 offspring were weaned on PND21 and were not exposed to DBP afterward. The age of vaginal opening and estrus onset, estrous cyclicity, c-Kit-ligand expression on ovarian granulosa cells, and the weight of ovaries and uterus of F1 female offspring were not affected, whereas serum levels of estradiol and progesterone were increased significantly by maternal exposure to 10 mg/kg/day DBP from GD12 to PND21. Although F1 ovarian function may not be adversely affected by maternal exposure to DBP, the increased reproductive hormone levels may interfere in F1 rat fertility.     

Maternal and fetal blood and organ toluene levels in rats following acute and repeated binge inhalation exposure

Inhalation of organic solvents is a persistent form of drug abuse with particular concern being the abuse of inhalants by women of child-bearing age. While studies have begun assessing postnatal outcomes of offspring exposed prenatally to inhalants, relatively little is known about the distribution of toluene in blood and body tissues of pregnant, inhalant-abusing women, or in the fetuses. The present study assessed the tissue toluene levels attained following brief toluene exposures using a pre-clinical rat model of maternal inhalant abuse. Timed-pregnant Sprague–Dawley rats were exposed to toluene at 8000 or 12,000 parts per million (ppm) for 15, 30 or 45 min/exposure. Exposures occurred twice each day from gestational day 8 (GD8) through GD20. Immediately following the second exposure on GD8, GD14 and GD20 blood was taken from the saphenous vein of the dams. Following saphenous vein blood collection on GD20, dams were sacrificed and trunk blood was collected along with maternal tissue specimens from cerebellum, heart, lung, kidney and liver. The placenta, amniotic fluid and fetal brain were also collected. Results demonstrated that maternal saphenous blood toluene levels increased as the inhaled concentration of toluene and duration of exposure increased. The maternal cerebellum, heart, kidney and liver appeared to be saturated after 30 min on GD20 such that toluene levels in those organs were equivalent across all ambient concentrations of inhaled toluene. Toluene levels also increased in fetal brain as the inhaled concentration of toluene increased and in placenta and amniotic fluid as the duration of exposure increased. Toluene levels in all tissues at GD20, except maternal lung and amniotic fluid, were higher than in maternal saphenous blood suggesting that toluene concentrated in those organs. Measurement of toluene levels in blood and other tissues following repeated toluene exposure demonstrated that toluene readily reaches a variety of potential sites of action throughout the maternal–placental–fetal unit.     

Kinetics of selected di-n-butyl phthalate metabolites and fetal testosterone following repeated and single administration in pregnant rats

Human exposure to phthalic acid diesters occurs through a variety of pathways as a result of their widespread use in consumer products and plastics. Repeated doses of di-n-butyl phthalate (DBP) from gestation day (GD) 12 to 19 disrupt testosterone synthesis and male sexual development in the fetal rat. Currently little is known about the disposition of DBP metabolites, such as monobutyl phthalate (MBP) and its glucuronide conjugate (MBP-G), during gestation after repeated exposure to DBP. In order to gain a better understanding of the effect of repeated dosing on maternal and fetal metabolism and distribution, pregnant Sprague–Dawley rats were given a single dose of 500 mg/kg DBP on GD 19 or daily doses of 50, 100, and 500 mg/(kg day) from GD 12 to 19 via corn oil gavage. Dose–response evaluation revealed a non-linear increase in maternal and fetal plasma concentrations of MBP. Maternal and fetal MBP levels were slightly lower in animals after 8 days of dosing at 500 mg/(kg day). Fetal plasma MBP levels closely followed maternal plasma, while the appearance and elimination of MBP-G in fetal plasma were significantly delayed. MBP-G accumulated over time in the amniotic fluid. Inhibition of testosterone was rapid in fetal testes when exposed to DBP (500 mg/(kg day)) on GD 19. Within 24 h, the level of inhibition in the fetus was similar between animals exposed to a single or multiple daily doses of 500 mg/(kg day). Examination of testosterone time-course data indicates a rapid recovery to normal levels within 24 h post-dosing at DBP doses of 50 and 100 mg/(kg day), with a rebound to higher than normal concentrations at later time-points. MBP kinetics in fetal testes allows direct comparison of active metabolite concentrations and testosterone response in the fetal testes.     

The effects of early life lead exposure on the expression of insulin-like growth factor 1 and 2 (IGF1, IGF2) in the hippocampus of mouse pups

The present study was undertaken to investigate the effects of maternal lead exposure on expression of IGF1 and IGF2 in the hippocampus of mice offspring. Lead exposure initiated from beginning of gestation to weaning. Lead acetate administered in drinking solutions was dissolved in distilled deionized water at the concentrations of 0.1%, 0.5% and 1% groups respectively. On the 21st postnatal day, the learning and memory ability was tested by Water Maze test and the Pb levels were also determined by graphite furnace atomic absorption spectrometry. The expression of IGF1 and IGF2 in hippocampus was examined by immunohistochemistry and western blotting. The lead levels in blood and hippocampus of all lead exposure groups were significantly higher than that of the control group (P < 0.05). In Water Maze test, the performances of 0.5% and 1% lead exposure groupswere worse than that of the control group (P < 0.05). The expression of IGF1 and IGF2 was decreased in lead exposed groups than that of the control group (P < 0.05). The low expression of IGF1 and IGF2 in the hippocampus of pups may contribute to the impairment of learning and memory associated with maternal Pb exposure.     

Genetic modification of the effect of maternal household air pollution exposure on birth weight in Guatemalan newborns

Low birth weight is associated with exposure to air pollution during pregnancy. The purpose of this study was to evaluate whether null polymorphisms of Glutathione S-transferases (GSTs), specifically GSTM1 and GSTT1 genes in infants or mothers, modify the association between high exposures to household air pollution (HAP) from cooking fires and birth weight. Pregnant women in rural Guatemala were randomized to receive a chimney stove or continue to use open fires for cooking. Newborns were measured within 48 h of birth. 132 mother–infant pairs provided infant genotypes (n = 130) and/or maternal genotypes (n = 116). Maternal null GSTM1 was associated with a 144 g (95% CI, −291, 1) and combined maternal/infant null GSTT1 was associated with a 155 g (95% CI, −303, −8) decrease in birth weight. Although there was a trend toward higher birth weights with increasing number of expressed GST genes, the effect modification by chimney stove use was not demonstrated.     

Polymorphisms of endothelin 1 (G5665T and T-1370G) and endothelin receptor type A (C+70G and G-231A) in Graves' disease

PurposeEndothelin 1 (EDN1) is a strong angiogenic and mitogenic factor, playing a key role in hypervascularization, thyroid follicle cell hyperplasia, and lymphocyte infiltration in the thyroid gland of patients with Graves’ disease (GD). EDN1 induces angiogenesis and mitogenesis via endothelin receptor type A (EDNRA). This study examined the possible association of EDN1 (G5665T and T-1370G) and EDNRA (C + 70G and G-231A) single nucleotide polymorphisms (SNPs) with the occurrence of GD, and evaluates the relationship between genotypes and clinical/laboratory manifestations of GD.Materials and methodsWe analyzed genotype and allele distributions of EDN1 and EDNRA polymorphisms in 165 patients with GD and 181 healthy controls by real-time PCR combined with melting curve analysis.ResultsNo significant associations between GD and variant alleles of the studied polymorphisms were observed. However, the anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) levels in EDN1 G5665T GG genotype were higher than those in T allele carriers (GT + TT) (p = 0.001 and p = 0.026, respectively). In addition, anti-TPO levels in EDN1 T-1370G wild-type homozygous patients were found to be higher than in mutant gene carrying patients (GT + GG) (p = 0.006). The presence of EDNRA + 70G allele was associated with 3.37-fold increased risk for development of ophthalmopathy in GD patients (p = 0.009).ConclusionAlthough there were no associations between EDN1 (G5665T and T-1370G) and EDNRA (C + 70G and G-231A) SNPs and susceptibility to GD, EDN1 G5665T and T-1370G polymorphisms were related to alterations of autoantibody production and EDNRA C + 70G polymorphism is related with increased risk for ophthalmopathy in GD patients.     

Indole-3-carbinol attenuates the deleterious gestational effects of bisphenol A exposure on the prostate gland of male F1 rats

Bisphenol A (BPA) is a chemical that has been investigated for it potential to cause prostate diseases. In this study, pregnant Sprague-Dawley rats were treated with 25 or 250 μg/kg BPA from gestational day (GD) 10 to GD21 with or without concurrent indole-3-carbinol (I3C) feeding. I3C is a phytochemical, and it affords chemoprotection against many types of neoplasia. Male F1 rats from different litters were euthanized on post-natal day (PND) 21 and PND180. BPA-treated groups showed a significant increase in histopathological lesions, but I3C feeding reversed many of these changes, mainly at PND180. Maternal I3C feeding increased prostate epithelial apoptosis in the BPA-treated groups and across age groups. Furthermore, I3C induced partial normalization of the prostate histoarchitecture. The results pointed to a protective effect of maternal I3C feeding during pregnancy in the BPA-exposed male offspring, thereby indicating reduction in the harmful effects of gestational BPA imprinting on the prostate.     

Assessment of fetal exposure risk following seminal excretion of a therapeutic IgG4 (T-IgG4) monoclonal antibody using a rabbit model

Studies were conducted in New Zealand White rabbits to assess the seminal transfer, vaginal absorption, and placental transfer of a therapeutic monoclonal antibody (T-IgG4). T-IgG4 was administered by intravenous injection (IV) in males and by IV and intravaginal routes in females. Low levels of T-IgG4 were excreted into seminal plasma (100- to 370-fold lower than serum concentrations) and absorbed following vaginal dosing (three orders of magnitude lower than IV administration). On gestation day 29 (GD29), fetal serum T-IgG4 levels were 1.5-fold greater than maternal levels following IV dosing. The fetal T-IgG4 exposure ratio for seminal transfer vs. direct maternal IV dosing was estimated to be 1.3 × 10⁻⁸. Applying human serum T-IgG4 exposure data to the model, the estimated human T-IgG4 serum concentration from seminal transfer was 3.07 × 10⁻⁷ μg/mL, an exposure level at least 1000-fold lower than the T-IgG4-ligand dissociation constant (K_d) and at least seven orders of magnitude lower than the in vivo concentration producing 20% inhibition of the target (EC₂₀). These data indicate that excretion of a T-IgG4 into semen would not result in a biologically meaningful exposure risk to the conceptus of an untreated partner.     

Alteration of serum sex hormonal profile in male gasoline filling station workers in respect to their polymorphism of glutathione S-transferase M1

Alterations in offspring sex ratio at birth and level of serum testosterone in filling-station workers have been reported. To determine the association of glutathione S-transferase M1 (GSTM1) polymorphism with serum levels of total testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) of male filling-station workers, the present study was carried out on 114 gasoline workers and 100 age- and sex-matched controls with no occupational exposure to gasoline. We have found no significant difference between the workers and controls for levels of sex hormones in the presence of active GSTM1 genotype. Among subjects with the GSTM1 null genotype, there was significant difference between exposed and unexposed subjects for the concentration of testosterone (t = 4.37, df = 97, P < 0.001). To investigate whether one null genotype could be compensated by an active genotype for the other isoenzyme, the mean concentrations of sex hormones was compared between the exposed and control groups with respect to their combinations of the GSTM1 and GSTT1 genotypes. The exposed group having either “null GSTM1/positive GSTT1” (t = 2.76, df = 72, P = 0.007) or “null GSTM1/null GSTT1” (t = 4.91, df = 23, P < 0.001) combinations had a lower testosterone compared with the controls. It seems that GSTM1 polymorphism has more effect on serum testosterone compared to the GSTT1 polymorphism, in exposed workers.     

In vivo preliminary investigations of the effects of the benzimidazole anthelmintic drug flubendazole on rat embryos and fetuses

Flubendazole, in a new formulation with high systemic bioavailability, has been proposed as a macrofilaricide against filarial diseases.To investigate embryotoxic activity, the new flubendazole formulation was administered orally to Sprague Dawley rats at 2, 3.46, 6.32 mg/kg/day on gestation day (GD) 9.5 and 10.5. Embryos/fetuses were evaluated on GD 11.5, 12.5 or 20.At 6.32 mg/kg/day (C_max = 0.801 μg/mL after single administration), flubendazole initially induced an arrest of embryonic development followed by a generalized cell death that led to 100% embryolethality by GD 12.5.At 3.46 mg/kg/day (C_max = 0.539 μg/mL after single administration), flubendazole markedly reduced embryonic development by GD 12.5 without causing cell death. On GD 20, 80% of fetuses showed malformations.At 2 mg/kg/day (C_max = 0.389 μg/mL after single administration), it did not interfere with rat embryofetal development.     

Safety profile of Hoodia gordonii extract: Mouse prenatal developmental toxicity study

Hoodia gordonii extract (0, 5, 15 or 50 mg/kg body weight/day, n = 24 mice/group) was orally administered by gavage to female CD-1 mice from gestation days 5–17. On gestation day 18 the females were euthanized and examined. Treatment at 50 mg/kg/day caused a marked reduction in feed intake and body weight gain. Feed consumption was sporadically reduced at 15 mg/kg/day. At 50 or 15 mg/kg/day fetal weights, ossification of some bones and full and empty uterus weights were reduced. There were no clear maternal or fetal effects at 5 mg/kg/day. Reproductive indices were unaffected at all doses and there were no treatment-related malformations, anomalies or variations. The overall study no-observed-adverse-effect level was set at 5 mg/kg/day.In summary, at doses that reduced maternal feed consumption, H. gordonii extract delayed fetal development. The fetal effects seen could be consequent to reduced maternal feed consumption, the desired biological activity of the test item.     

Adverse effects of diisooctyl phthalate on the male rat reproductive development following prenatal exposure

In a first study, rats were given diisooctyl phthalate (DIOP, CAS 27554-26-3) at 0, 0.1, 0.5, and 1 g/kg/day, by gavage, on gestation days 6–20 (GD). There was a significant increase in resorptions at 1 g/kg/day and a reduction in fetal weights at 0.5 and 1 g/kg/day. Malpositioned testes were observed in fetuses at 1 g/kg/day, and supernumerary lumbar ribs and ossification delay at 0.5 and 1 g/kg/day. In a follow-up study, DIOP administered on GD 12–19 reduced fetal testicular testosterone at 0.1 g/kg/day and above. Finally, postnatal reproductive assessment was conducted in adult male offspring prenatally exposed to DIOP on GD 12–21. Abnormalities of reproductive system (e.g. hypospadias, non scrotal testes, and hypospermatogenesis) were observed in a few adult males at 0.5 g/kg/day, and with a high incidence at 1 g/kg/day. Thus, DIOP displayed an antiandrogenic activity and disrupted the male reproductive development.     

Estrogenicity of food-associated estrogenic compounds in the fetuses of female transgenic mice upon oral and IP maternal exposure

The present study investigated to what extent seven food-associated in vitro estrogenic compounds can induce estrogenic effects in the fetuses of pregnant female mice with an estrogen receptor (ER)-mediated luciferase (luc) reporter gene system. The luc-induction was determined either 8 h after maternal dosing with a single intraperitoneal (IP) dose or 24 h after the last of a series of 8 daily oral dosages. Three known estrogens, 17β-estradiol (E₂), 17α-ethynylestradiol (EE) and 17β-estradiol 3,17-dipropionate (EP) were used as positive controls at 1 mg/kg bw and DMSO as solvent control. The food-associated estrogenic compounds tested were: bisphenol A (BPA), nonylphenol (NP) both at 50 mg/kg bw, dichlorodiphenyldichloroethylene (p,p′-DDE) at 50 mg/kg bw, quercetin at 16.6 mg/kg bw, and di-isoheptyl phthalate (DIHP), di-(2-ethylhexyl) phthalate (DEHP) and di-(2-ethylhexyl) adipate (DEHA) all at 100 mg/kg bw. Exposure to E₂, EE and EP resulted in significant luc inductions upon both oral and/or IP dosing in a variety of tissues including liver, tibia and femurs, and upon IP dosing also in fetuses.BPA, NP, DEHA, DEHP, DIHP, DDE and quercetin were unable to significantly induce luc activity in fetuses. However, after maternal oral exposure during gestation to NP, BPA and DIHP placental luc activity was significantly lowered.The results indicate that at the current levels of exposure to food-associated estrogenic compounds, estrogenic effects to the fetus are not expected. The significant luc reduction in the placenta, should be further studied for its significance for fetal development and relevance for the human situation.     

Inhibition of vascular endothelial growth factor-mediated angiogenesis involved in reproductive toxicity induced by sesquiterpenoids of Curcuma zedoaria in rats

The use of herbal medicine has rapidly increased in recent decades, prompting an increase in toxicity concerns. Here we investigated whether and how essential oil of Curcuma zedoaria may induce reproductive and developmental toxicity. Whole embryo culture in rats revealed that the essential oil produced a concentration-dependent toxicity ex vivo in the embryos on gestation Day 9.5 (GD9.5). Weight loss, abnormal hematological and biochemical effects on dams and embryos were also observed in GD17 pregnant rats orally administrated with 100 mg kg⁻¹ or 200 mg kg⁻¹ essential oil from GD7 onward. Induction of embryotoxicity may be related to placental calcification attributed to inhibition of vascular endothelial growth factor (VEGF)-mediated angiogenesis. Analysis by gas chromatography–mass spectrometry demonstrated that the main toxic compounds in essential oil were sesquiterpenoids. Our results suggest that the reproductive toxicity of C. zedoaria may be caused by sesquiterpenoids in the essential oil blocking VEGF-mediated angiogenesis.     

Arg25Pro (c.915G>C) polymorphism of transforming growth factor β1 gene increases the risk of developing Graves' disease

BackgroundGraves' disease (GD) arises due to complex interactions between genetic and environmental factors. Transforming growth factor β1 (TGFβ1) is required to maintain immune homeostasis, and is implicated in lymphocyte infiltration, thyroid follicular cell hyperplasia, and production of autoantibody in the thyroid gland of patients with GD.AimThe aim of the present study was to investigate the possible association of Leu10Pro (c.869T>C) and Arg25Pro (c.915G>C) single nucleotide polymorphisms (SNPs) of TGFβ1 gene with the occurrence of GD.MethodsWe analyzed the genotype and allele frequencies of these SNPs in 171 patients with GD and 197 healthy controls using PCR-restriction fragment length polymorphism (RFLP).ResultsThe distribution of Leu10Pro (c.869T>C) genotype and allele frequencies in the control and GD groups were not significantly different. However, there was a significant increase of Arg25Pro (c.915G>C) C allele frequency in patients with GD compared with healthy controls (p < 0.0001, OR = 4.77, 95% CI = 3.32–7.03). In addition, C allele carrying subjects (CG + CC) had 5.31-fold increased risk for developing GD according to GG homozygotes (p < 0.0001, 95% CI = 3.43–8.44). No association between polymorphisms and GD phenotypes was observed.ConclusionThis study indicates that the Arg25Pro (c.915G>C) polymorphism of TGFβ1 gene may be related to occurrence of GD.     

Developmental toxicity of hexachloronaphthalene in Wistar rats. A role of CYP1A1 expression

Hexachloronaphthalene (HxCN) is one of the most toxic congeners of polychlorinated naphthalenes (PCNs). This study assesses the prenatal toxicity of HxCN after daily administration at doses of 0.1–1.0 mg/kg b.w. to pregnant Wistar rats during organogenesis. We evaluated also the expression of CYP1A1 mRNA and protein in the livers of dams and fetuses, as well as the placenta. The results indicate that 0.3 mg/kg b.w. was the lowest HxCN toxic dose for dams (LOAEL) while a dose of 0.1 mg/kg b.w. was sufficient to impair the intrauterine development of embryos/fetuses without maternal toxicity. Regardless of the applied dose, HxCN generated embryotoxic effects. Dose-dependent fetotoxic effects were associated with HxCN exposure. HxCN was found to be a strong inducer of maternal and fetal CYP1A1. Expression of CYP1A1 mRNA in the placenta appears to be the most sensitive marker of HxCN exposure.     

Mercury modulates the cytochrome P450 1a1, 1a2 and 1b1 in C57BL/6J mice: in vivo and in vitro studies

In the current study C57BL/6J mice were injected intraperitoneally with Hg^2 + in the absence and presence of TCDD. After 6 and 24 h the liver was harvested and the expression of Cyps was determined. In vitro, isolated hepatocytes were incubated with TCDD in the presence and absence of Hg^2 +. At the in vivo level, Hg^2 + significantly decreased the TCDD-mediated induction of Cyps at 6 h while potentiating their levels at 24 h. In vitro, Hg^2 + significantly inhibited the TCDD-mediated induction of Cyp1a1 in a concentration- and time-dependent manner. Interestingly, Hg^2 + increased the serum hemoglobin (Hb) levels in mice treated for 24 h. Upon treatment of isolated hepatocytes with Hb alone, there was an increase in the AhR-dependent luciferase activity with a subsequent increase in Cyp1a1 protein and catalytic activity levels. Importantly, when hepatocytes were treated for 2 h with Hg^2 + in the presence of TCDD, then the medium was replaced with new medium containing Hb, there was potentiation of the TCDD-mediated effect. In addition, Hg^2 + increased heme oxygenase-1 (HO-1) mRNA, which coincided with a decrease in the Cyp1a1 activity level. When the competitive HO-1 inhibitor, tin mesoporphyrin was applied to the hepatocytes there was a partial restoration of Hg^2 +-mediated inhibition of Cyp1a1 activity. In conclusion, we demonstrate for the first time that there is a differential modulation of the TCDD-mediated induction of Cyp1a1 by Hg^2 + in C57BL/6J mice livers and isolated hepatocytes. Moreover, this study implicates Hb as an in vivo specific modulator of Cyp1 family.