title: Validation of a genomics-based hypothetical adverse outcome pathway: 2,4-dinitrotoluene perturbs PPAR signaling thus impairing energy metabolism and exercise endurance.
abstract: 2,4-dinitrotoluene (2,4-DNT) is a nitroaromatic used in industrial dyes and explosives manufacturing processes that is found as a contaminant in the environment. Previous studies have implicated antagonism of PPARα signaling as a principal process affected by 2,4-DNT. Here, we test the hypothesis that 2,4-DNT-induced perturbations in PPARα signaling and resultant downstream deficits in energy metabolism, especially from lipids, cause organism-level impacts on exercise endurance. PPAR nuclear activation bioassays demonstrated inhibition of PPARα signaling by 2,4-DNT whereas PPARγ signaling increased. PPARα (-/-) and wild-type (WT) female mice were exposed for 14 days to vehicle or 2,4-DNT (134 mg/kg/day) and performed a forced swim to exhaustion 1 day after the last dose. 2,4-DNT significantly decreased body weights and swim times in WTs, but effects were significantly mitigated in PPARα (-/-) mice. 2,4-DNT decreased transcript expression for genes downstream in the PPARα signaling pathway, principally genes involved in fatty acid transport. Results indicate that PPARγ signaling increased resulting in enhanced cycling of lipid and carbohydrate substrates into glycolytic/gluconeogenic pathways favoring energy production versus storage in 2,4-DNT-exposed WT and PPARα (-/-) mice. PPARα (-/-) mice appear to have compensated for the loss of PPARα by shifting energy metabolism to PPARα-independent pathways resulting in lower sensitivity to 2,4-DNT when compared with WT mice. Our results validate 2,4-DNT-induced perturbation of PPARα signaling as the molecular initiating event for impaired energy metabolism, weight loss, and decreased exercise performance.
authors.affiliation: Army Engineer Research and Development Center, Vicksburg, Mississippi 39180 mitchell.s.wilbanks@usace.army.mil.
authors.forename: Mitchell S
authors.initials: MS
authors.lastname: Wilbanks
authors.affiliation: Army Engineer Research and Development Center, Vicksburg, Mississippi 39180.
authors.forename: Kurt A
authors.initials: KA
authors.lastname: Gust
authors.affiliation: University of Louisiana at Monroe, Monroe, Louisiana 71201.
authors.forename: Sahar
authors.initials: S
authors.lastname: Atwa
authors.affiliation: University of Mississippi Medical Center, Jackson, Mississippi 39216.
authors.forename: Imran
authors.initials: I
authors.lastname: Sunesara
authors.affiliation: Army Engineer Research and Development Center, Vicksburg, Mississippi 39180 Conestoga-Rovers & Associates, Dallas, Texas 75234.
authors.forename: David
authors.initials: D
authors.lastname: Johnson
authors.affiliation: Badger Technical Services, San Antonio, Texas 71286.
authors.forename: Choo Yaw
authors.initials: CY
authors.lastname: Ang
authors.affiliation: University of Louisiana at Monroe, Monroe, Louisiana 71201.
authors.forename: Sharon A
authors.initials: SA
authors.lastname: Meyer
authors.affiliation: Army Engineer Research and Development Center, Vicksburg, Mississippi 39180.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Perkins
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004136:Dinitrobenzenes / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects / Q000235:genetics*; D004785:Environmental Pollutants / Q000633:toxicity*; D023281:Genomics; D006003:Glycogen / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D047493:PPAR alpha / Q000235:genetics / Q000378:metabolism*; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism*; D010807:Physical Endurance / Q000187:drug effects / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013550:Swimming
chemical_list: D004136:Dinitrobenzenes; D004785:Environmental Pollutants; D047493:PPAR alpha; D047495:PPAR gamma; C016403:2,4-dinitrotoluene; D006003:Glycogen
keywords: PPAR; adverse outcome pathway; dinitrotoluene; energy