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Gene expression profiles following exposure to a developmental neurotoxicant, Aroclor 1254: Pathway analysis for possible mode(s) of action.
Citation:
ROYLAND, J. E. AND PRASADA RAO S. KODAVANTI. Gene expression profiles following exposure to a developmental neurotoxicant, Aroclor 1254: Pathway analysis for possible mode(s) of action. TOXICOLOGY AND APPLIED PHARMACOLOGY. Academic Press Incorporated, Orlando, FL, 231(2):179-196, (2008).
Impact/Purpose:
Support criteria for MYP
Description:
Epidemiological studies indicate that low levels of polychlorinated biphenyl (PCB) exposure can adversely affect neurocognitive development. In animal models, perturbations in calcium signaling, neurotransmitters, and thyroid hormones have been postulated as potential mechanisms for PCB-induced developmental neurotoxicity. In order to understand the role of these proposed mechanisms and to identify other mechanisms in PCB-induced neurotoxicity, we have chosen a global approach utilizing oligonucleotide microarrays to examine gene expression profiles in the brain following developmental exposure to Aroclor 1254 (0 or 6 mg/kg/day from gestation day 6 through postnatal day (PND) 21) in Long Evans rats. Gene expression levels in the cerebellum and hippocampus from PND7 and 14 animals were determined on Affymetrix rat 230A_2.0 chips. In the cerebellum, 87 transcripts were altered at PND7 compared to 27 transcripts at PND14 by Aroclor 1254 exposure, with only one transcript affected at both ages. In hippocampus, 175 transcripts and 50 transcripts were altered at PND7 and PND14, respectively, by Aroclor 1254 exposure with five genes commonly affected. Functional analysis suggests that pathways related to calcium homeostasis (Gng3, Ryr2, Trdn, Cacna1a), intracellular signaling (Camk2d, Stk17b, Pacsin2, Ryr2, Trio, Fert2, Ptk2b), axonal guidance (Lum, Mxd3, Akap11, Gucy1b3), aryl hydrocarbon receptor signaling (Nfia, Col1a2), and transcripts involved in cell proliferation (Gspt2, Cdkn1c, Ptk2b) and differentiation (Ifitm31, Hpca, Zfp260, Igsf4a, Hes5) leading to the development of nervous system were significantly altered by Aroclor 1254 exposure. Of the two brain regions examined, Aroclor 1254-induced genomic changes were greater in the hippocampus than the cerebellum. The genomic data support our hypothesis that PCB-induced neurotoxic effects were due to disruption of normal ontogenetic pattern of nervous system growth and development by altering intracellular signaling pathways.
