title: Induction of oxidative stress in the tissues of rats after chronic exposure to TCDD, 2,3,4,7,8-pentachlorodibenzofuran, and 3,3',4,4',5-pentachlorobiphenyl.
abstract: The abilities of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), 3,3',4,4',5-pentachlorobiphenyl (PCB126), and mixtures of these xenobiotics (toxic equivalents, TEQs) to induce oxidative stress in hepatic and brain tissues of rats have been investigated after chronic (30 wk) exposure to these congeners. TCDD, PeCDF, PCB126, and TEQs were administered daily to groups of rats at doses that corresponded to their toxic equivalency factors (TEFs), and the biomarkers of oxidative stress, including the production of superoxide anion, lipid peroxidation, and DNA single-strand breaks (SSBs), were determined in hepatic and brain tissues at the end of the exposure period. The three chemicals caused similar dose-dependent increases in the production of superoxide anion, lipid peroxidation, and DNA SSBs, which plateaued at certain dose ranges, followed by secondary increases at the higher dose levels. Similar effects were also produced by the TEQs; however, the dose-dependent increases in the biomarkers of oxidative stress were continuous and never achieved plateau levels. Except for PCB126, where statistical analyses revealed greater productions of superoxide anion and lipid peroxidation in brain tissues as compared with hepatic tissues, no significant differences were revealed between the two tissues in response to the other xenobiotics or the TEQs. Nonsignificant differences were also revealed when comparing the effects induced by the TEQs with those induced by the individual chemicals.
authors.affiliation: College of Pharmacy, University of Toledo, Ohio 43606, USA. ehassou@utnet.utoledo.edu
authors.forename: Ezdihar A
authors.initials: EA
authors.lastname: Hassoun
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Ahmed
authors.initials: A
authors.lastname: Abushaban
authors.forename: Sidney J
authors.initials: SJ
authors.lastname: Stohs
mesh_terms: D000818:Animals; D001572:Benzofurans / Q000009:adverse effects*; D001921:Brain / Q000187:drug effects / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000009:adverse effects*; D004965:Estrogen Antagonists / Q000009:adverse effects*; D005260:Female; D008099:Liver / Q000187:drug effects / Q000473:pathology; D018384:Oxidative Stress; D011078:Polychlorinated Biphenyls / Q000009:adverse effects*; D000072317:Polychlorinated Dibenzodioxins / Q000009:adverse effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001572:Benzofurans; D004785:Environmental Pollutants; D004965:Estrogen Antagonists; D000072317:Polychlorinated Dibenzodioxins; D011078:Polychlorinated Biphenyls; C023035:3,4,5,3',4'-pentachlorobiphenyl; C038890:2,3,4,7,8-pentachlorodibenzofuran