Project description:Pregnant rats (Long-Evans) were dosed perinatally with 0 or 6 mg/kg/day of Aroclor 1254 from gestation day 6 through postnatal day (PND) 21. Gene expression in cerebellum and hippocampus from PND7 and PND14 animals was analyzed with an emphasis on developmental aspects. Changes in gene expression (≥ 1.5 fold) in control animals identified normal developmental changes. These basal levels of expression were compared to data from Aroclor 1254-treated animals to determine the impact of gestational PCB exposure on developmental parameters. The results indicate that the expression of a number of developmental genes related to cell cycle, synaptic function, cell maintenance, and neurogenesis is significantly altered from PND7 to PND14. Aroclor 1254 treatment appears to dampen the overall growth-related gene expression levels in both regions with the effect being more pronounced in the cerebellum. Functional analysis suggests that Aroclor 1254 delays maturation of the developing nervous system, with the consequences dependent on the ontological state of the brain area and the functional role of the individual gene. Keywords: time course, stress response
Project description:Chronic exposure of Sprague-Dawley (SD) rats to either 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or Aroclor 1254 results in female-selective induction of hepatic tumors. The relative potency of dioxins and PCB mixtures, such as Aroclor 1254, is often estimated using the internationally endorsed toxic equivalency (TEQ) approach. Comparing the genome wide changes in gene expression in both genders following exposure to toxic equivalent doses of these chemicals should identify critical sets of early response genes while further defining the concept of the TEQ of halogenated aromatic hydrocarbons. Aroclor 1254 at 0.6, 6.0 and 60 mg/kg body weight and TEQ doses of TCDD (0.3 and 3.0 µg/kg), calculated to match the top two Aroclor 1254 doses, were orally administered to SD rats for three consecutive days. Day 4 gene expression in hepatic tissue was determined using microarrays. A linear mixed-effects statistical model was developed to analyze the data in relation to treatment, gender, and gender*treatment (G*T) interactions. The genes most changed included 54 genes with and 51 genes without a significant model G*T term. The known aryl hydrocarbon receptor (AHR) battery genes (Cyp1a1, Cyp1a2, Cyp1b1, Aldh3a1), and novel genes, responded in a TEQ dose-dependent manner in both genders. However, an important observation was the apparent disruption of sexually dimorphic basal gene expression, particularly for female rats. Since many of these genes are involved in steroid metabolism, exposure to either TCDD or Aroclor 1254 could disrupt proliferative signals more in female rats as a possible consequence of altered estrogen metabolism. This study extends the findings of previous rodent bioassays by identifying groups of genes, other than the well-characterized AHR response genes, whose disruption may be important in the tumorigenic mechanism in this rat strain. Keywords: dose response, Multifactor Linear Model
Project description:Pregnant rats (Long-Evans) were dosed perinatally with 0 or 6Â mg/kg/day of Aroclor 1254 from gestation day 6 through postnatal day (PND) 21. Gene expression in cerebellum and hippocampus from PND7 and PND14 animals was analyzed with an emphasis on developmental aspects. Changes in gene expression (>= 1.5 fold) in control animals identified normal developmental changes. These basal levels of expression were compared to data from Aroclor 1254-treated animals to determine the impact of gestational PCB exposure on developmental parameters. The results indicate that the expression of a number of developmental genes related to cell cycle, synaptic function, cell maintenance, and neurogenesis is significantly altered from PND7 to PND14. Aroclor 1254 treatment appears to dampen the overall growth-related gene expression levels in both regions with the effect being more pronounced in the cerebellum. Functional analysis suggests that Aroclor 1254 delays maturation of the developing nervous system, with the consequences dependent on the ontological state of the brain area and the functional role of the individual gene. Experiment Overall Design: Pregnant rats (Long-Evans) were dosed perinatally with 0 or 6Â mg/kg/day of Aroclor 1254 from gestation day 6 through postnatal day (PND) 21. Gene expression in cerebellum and hippocampus from PND7 and PND14 animals was analyzed with an emphasis on developmental aspects.
Project description:In order to determine molecular rules for transcriptional regulation of targeted genes to explain in part the pleiotropic effect observed in animals and humans upon exposure to Aroclor 1254 we treated human hepatocytes with Aroclor1254 and analysed RNA expression using a Nimblegene human custom array. Keywords: Human hepatocytes, Aroclor1254 treatment, 20µM, 72h
Project description:In order to determine molecular rules for transcriptional regulation of targeted genes to explain in part the pleiotropic effect observed in animals and humans upon exposure to Aroclor 1254 we treated human hepatocytes with Aroclor1254 and analysed RNA expression using a Nimblegene human custom array. Human hepatocytes isolated from surgical material were treated with 20µM Aroclor1254 for 72h. Non-treated cells served as control. Total RNA was isolated using QIAGEN´s RNeasy total RNA isolation kit according to the manufacturerâs recommendations. Oligonucleotide microarrays were hybridized and washed according to the manufacturerâs recommendations.
Project description:Exposure to polychlorinated biphenyls (PCBs) and high fat diet (HFD) results in nonalcoholic steatohepatitis (NASH) in mice by altering intracellular signaling and inhibiting epidermal growth factor receptor (EGFR) signaling. Post-transcriptional chemical modification (PTM) of RNA regulates biological processes. This study tested the hypothesis that PCB exposure alters the global RNA epitranscriptome in HFD-fed male mouse liver. C57BL/6J male mice were fed a 42% milk fat diet (HFD) and exposed to Aroclor 1260 (20mg/kg), PCB 126 (20 µg/kg), both Aroclor 1260 and PCB 126, or vehicle control for 12 weeks. RNA modifications altered by PCB exposure were analyzed in comparison to the readers, writers, and erasers of these marks in the RNA transcriptome.