title: Mechanistic Investigations Into the Developmental Toxicity of Nitrated and Heterocyclic PAHs.
abstract: Nitrated polycyclic aromatic hydrocarbons (NPAHs) and heterocyclic PAHs (HPAHs) are recognized environmental pollutants. However, the health risks of NPAHs and HPAHs to humans and environmental systems are not well-studied. The developmental zebrafish (Danio rerio) model was used to evaluate the toxicity of a structurally diverse set of 27 NPAHs and 10 HPAHs. The individual activity of each compound towards the aryl hydrocarbon receptor (AHR), including the role of the AHR in observed toxicity, and genetic markers of oxidative stress and cardiac toxicity were evaluated. Zebrafish embryos were exposed from 6 to 120 hours post fertilization (hpf), to a broad concentration range of individual compounds, and evaluated for 22 developmental endpoints. The potential role of AHR was determined using the transgenic Tg(cyp1a:nls-egfp) reporter zebrafish line. All compounds were screened computationally through molecular docking using a previously developed AHR models of zebrafish isoforms 1A, 1B, and 2. Some compounds did not induce observable developmental toxic responses, whereas others produced statistically significant concentration-dependent toxicity. The tested compounds also exhibited a range of predicted AHR binding and cyp1a/GFP induction patterns, including cyp1a expression in the liver, vasculature, skin, and yolk, which we determined to be due to distinct isoforms of the AHR, using morpholino oligonucleotide knockdown. Furthermore, we investigated mRNA expression of oxidative and cardiac stress genes at 48 and 120 hpf, which indicated several potential mechanisms-of-action for NPAHs. Overall, we observed a range of developmental toxicities, cyp1a/GFP expression patterns, and gene expression profiles, suggestive of several potential mechanisms of action.
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon, USA.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Chlebowski
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon, USA.
authors.forename: Gloria R
authors.initials: GR
authors.lastname: Garcia
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon, USA.
authors.forename: Jane K
authors.initials: JK
authors.lastname: La Du
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon, USA.
authors.forename: William H
authors.initials: WH
authors.lastname: Bisson
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Truong
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon, USA.|Department of Chemistry, Oregon State University, Corvallis, Oregon, USA.
authors.forename: Staci L
authors.initials: SL
authors.lastname: Massey Simonich
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Tanguay
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics; D055785:Gene Knockdown Techniques; D006571:Heterocyclic Compounds / Q000633:toxicity*; D006844:Hydrocarbons, Cyclic / Q000737:chemistry / Q000633:toxicity*; D009566:Nitrates / Q000737:chemistry*; D018384:Oxidative Stress / Q000187:drug effects; D018336:Receptors, Aryl Hydrocarbon / Q000187:drug effects / Q000235:genetics; D013312:Stress, Physiological / Q000187:drug effects; D013723:Teratogens / Q000633:toxicity*; D015027:Zebrafish
chemical_list: D006571:Heterocyclic Compounds; D006844:Hydrocarbons, Cyclic; D009566:Nitrates; D018336:Receptors, Aryl Hydrocarbon; D013723:Teratogens; D019363:Cytochrome P-450 CYP1A1
keywords: aryl hydrocarbon receptor; heterocyclic polycyclic aromatic hydrocarbon; nitrated polycyclic aromatic hydrocarbon; zebrafish