Project description:To identify liver transcripts differentially expressed between control samples and animals exposed to PBDE-47, we collected RNA from male pups at postnatal day 4 (PND4) after the Wistar Han dams were exposed to 0, 0.1, 15, or 50 mg/kg PBDE-47. These samples were interrogated with the Affymetrix Rat Genome 230 2.0 GeneChip array. A total of 7, 50, and 149 gene transcripts were differentially expressed between control samples and 0.1, 15, and 50 mg/kg PBDE-47 (using a false discovery rate (FDR) threshold of 0.05). These transcripts were mapped to 2, 40, and 139 genes using Ingenuity Pathway Analysis.
Project description:Pentabromodiphenyl ethers (PBDE) are found in human tissue, in household dust, and in the environment, and a particular concern is the potential for the induction of cancer pathways from these fat-soluble persistent organic pollutants. Only one PBDE cancer study has been conducted and that was for a PBDE mixture (DE-71). Because it is not feasible to test all PBDE congeners in the environment for cancer potential, it is important to develop a set of biological endpoints that can be used in short-term toxicity studies to predict disease outcome after long-term exposures. In this study, PBDE-47 was selected as the test PBDE congener to evaluate and compare toxicity to that of the carcinogenic PBDE mixture. The toxicities of PBDE-47 and the PBDE mixture were evaluated at PND 22 in Wistar Han rat (Crl: WI (Han)) pups after in utero/postnatal exposure (0, 0.1, 15, or 50 mg/kg; dams, GD6-21; pups, PND 12-PND 21; oral gavage daily dosing). By PND 22, PBDE-47 caused centrilobular hypertrophy and fatty change in liver, and reduced serum thyroxin (T4) levels; similar effects were also observed after PBDE mixture exposure. Transcriptomic changes in the liver included induction of cytochrome p450 transcripts and up-regulation of Nrf2 antioxidant pathway transcripts and ABC membrane transport transcripts. Decreases in other transport transcripts (ABCG5 & 8) provided a plausible mechanism for lipid accumulation, characterized by a treatment-related liver fatty change after PBDE-47 and PBDE mixture exposure. The benchmark dose calculation based on liver transcriptomic data was generally lower for PBDE-47 than for the PBDE mixture. The up-regulation of the Nrf2 antioxidant pathway and changes in metabolic transcripts after PBDE-47 and PBDE mixture exposure suggest that PBDE-47, like the PBDE mixture (NTP 2016, TR 589), could be a liver toxin/carcinogen after long-term exposure.
Project description:To identify liver transcripts differentially expressed between control samples and animals exposed to DE-71, we collected RNA from male pups at postnatal day 4 (PND4) after the Wistar Han dams were exposed to 0, 0.1, 15, or 50 mg/kg DE-71. These samples were interrogated with the Affymetrix Rat Genome 230 2.0 GeneChip array A total of 0, 15, and 162 gene transcripts were differentially expressed between control samples and 0.1, 15, and 50 mg/kg DE-71, respectively (using a false discovery rate (FDR) threshold of 0.05). These transcripts were mapped to 0, 13, and 161 genes using Ingenuity Pathway Analysis.
Project description:Test articles used: DE-71 (Pentabromodiphenyl Ether Mixture [Technical Grade), CAS Number 32534-81-9, DTXSID2024246); PBDE-47 (CAS Number 5436-43-1); PB (Phenobarbital, CAS Number 50-06-6 ); PCB (PCB126, CAS Number 57465-28-8)
Project description:Polybrominated diphenyl ethers (PBDEs) are legacy compounds with continued widespread human exposure. Despite this, developmental toxicity studies of DE-71, a mixture of PBDEs, are scarce and its potential for endocrine disrupting effects in vivo is not well covered. To address this knowledge gap, we carried out a developmental exposure study with DE-71. Pregnant Wistar rat dams were exposed to 0, 40 or 60 mg/kg bodyweight/day from gestation day 7 to postnatal day 16, and both sexes were examined. Developmental exposure affected a range of reproductive toxicity endpoints. Effects were seen for both male and female anogenital distances (AGD), with exposed offspring of either sex displaying around 10% shorter AGD compared to controls. Both absolute and relative prostate weights were markedly reduced in exposed male offspring, with about 40% relative to controls. DE-71 reduced mammary gland outgrowth, especially in male offspring. These developmental in vivo effects suggest a complex effect pattern involving anti-androgenic, anti-estrogenic and maybe estrogenic mechanisms depending on tissues and developmental stages. Irrespective of the specific underlying mechanisms, these in vivo results corroborate that DE-71 causes endocrine disrupting effects and raises concern for the effects of PBDE-exposure on human reproductive health, including any potential long-term consequences of disrupted mammary gland development.
Project description:Liver gene transcripts patterns were used to characterize toxicity from exposure to polybrominated diphenyl ethers (PBDEs), flame retardant components. In this study, Wistar Han dams were exposed by gavage to the PBDE mixture (DE71) starting at gestation day 6 (GD 6) and continuing to weaning on postnatal day 21 (PND 21). Offspring from the dams began PBDE direct dosing on PND 12 and were dosed daily through PND 21. After weaning, they were dosed 5 days per week for another 13 weeks. Liver samples were collected at PND 22 and week 13 for liver gene expression analysis and interrogated with the Affymetrix Rat Genome 230 2.0 Array. PBDE treatment induced 1,066 liver gene transcript changes in females and 1,200 transcriptional changes in males at PND 22 (false discovery rate (FDR) < 0.01), but only 263 liver transcriptional changes at 13 weeks in male rats (FDR <0.05). No significant differences in dose response were found between male and female pups.
