title: Transcriptional profiling of the mouse hippocampus supports an NMDAR-mediated neurotoxic mode of action for benzo[a]pyrene.
abstract: Benzo[a]pyrene (BaP) is a genotoxic carcinogen and a neurotoxicant. The neurotoxicity of BaP is proposed to arise from either genotoxicity leading to neuronal cell death, or perturbed expression of N-methyl-d-aspartate receptor (NMDAR) subunits. To explore these hypotheses, we profiled hippocampal gene expression of adult male Muta(™) Mouse administered 0, 1, 35, or 70 mg BaP/kg bw per day by oral gavage for 3 days. Transcriptional profiles were examined by RNA-sequencing (RNA-seq), DNA microarrays, and real-time quantitative reverse transcription polymerase chain reaction (RT-PCR). BaP-DNA adducts in the cerebellum were quantified by (32) P-post-labeling to measure genotoxicity. RNA-seq revealed altered expression of 0, 260, and 219 genes (P-value < 0.05, fold-change ≥ ± 1.5) following exposure to the low, medium, and high doses, respectively; 54 genes were confirmed by microarrays. Microarray and RT-PCR analysis showed increased expression of NMDAR subunits Grina and Grin2a. In contrast, no effects on DNA-damage response genes were observed despite comparable BaP-DNA adduct levels in the cerebellum and in the lungs and livers of mice at similar BaP doses in previous studies. The results suggest that DNA-damage response does not play a major role in BaP-induced adult neurotoxicity. Meta-analysis revealed that BaP-induced transcriptional profiles are highly correlated with those from the hippocampus of transgenic mice exhibiting similar neurotoxicity outcomes to BaP-exposed mice and rats (i.e., defects in learning and memory). Overall, we suggest that BaP-induced neurotoxicity is more likely to be a consequence of NMDAR perturbation than genotoxicity, and identify other important genes potentially mediating this adverse outcome. Environ. Mol. Mutagen. 57:350-363, 2016. © 2016 Her Majesty the Queen in Right of Canada. Environmental and Molecular Mutagenesis © 2016 Environmental Mutagen Society.
authors.affiliation: Environmental Health Science and Research Bureau, Environmental and Radiation Health Sciences Directorate, HECSB, Health Canada, Ottawa, Ontario, Canada, K1A 0K9.
authors.forename: Nikolai L
authors.initials: NL
authors.lastname: Chepelev
authors.affiliation: Environmental Health Science and Research Bureau, Environmental and Radiation Health Sciences Directorate, HECSB, Health Canada, Ottawa, Ontario, Canada, K1A 0K9.
authors.forename: Alexandra S
authors.initials: AS
authors.lastname: Long
authors.affiliation: Environmental Health Science and Research Bureau, Environmental and Radiation Health Sciences Directorate, HECSB, Health Canada, Ottawa, Ontario, Canada, K1A 0K9.
authors.forename: Wayne J
authors.initials: WJ
authors.lastname: Bowers
authors.affiliation: Environmental Health Science and Research Bureau, Environmental and Radiation Health Sciences Directorate, HECSB, Health Canada, Ottawa, Ontario, Canada, K1A 0K9.
authors.forename: Rémi
authors.initials: R
authors.lastname: Gagné
authors.affiliation: Environmental Health Science and Research Bureau, Environmental and Radiation Health Sciences Directorate, HECSB, Health Canada, Ottawa, Ontario, Canada, K1A 0K9.
authors.forename: Andrew
authors.initials: A
authors.lastname: Williams
authors.affiliation: Environmental Health Science and Research Bureau, Environmental and Radiation Health Sciences Directorate, HECSB, Health Canada, Ottawa, Ontario, Canada, K1A 0K9.
authors.forename: Byron
authors.initials: B
authors.lastname: Kuo
authors.affiliation: Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King's College London, London, SE1 9NH, United Kingdom.
authors.forename: David H
authors.initials: DH
authors.lastname: Phillips
authors.affiliation: Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King's College London, London, SE1 9NH, United Kingdom.
authors.forename: Volker M
authors.initials: VM
authors.lastname: Arlt
authors.affiliation: Environmental Health Science and Research Bureau, Environmental and Radiation Health Sciences Directorate, HECSB, Health Canada, Ottawa, Ontario, Canada, K1A 0K9.
authors.forename: Paul A
authors.initials: PA
authors.lastname: White
authors.affiliation: Environmental Health Science and Research Bureau, Environmental and Radiation Health Sciences Directorate, HECSB, Health Canada, Ottawa, Ontario, Canada, K1A 0K9.
authors.forename: Carole L
authors.initials: CL
authors.lastname: Yauk
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000378:metabolism / Q000633:toxicity*; D018736:DNA Adducts / Q000378:metabolism; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D020869:Gene Expression Profiling; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008815:Mice, Inbred Strains; D020258:Neurotoxicity Syndromes / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome
chemical_list: D018736:DNA Adducts; D016194:Receptors, N-Methyl-D-Aspartate; C056612:benzo(a)pyrene-DNA adduct; D001564:Benzo(a)pyrene
keywords: glutamate receptor; human health risk assessment; learning and memory; mode of action; toxicogenomics