PARENT SESSION
PT2 - Endocrine Disruption
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P535) Effects of Natural and Synthetic Estrogens on Largemouth Bass Hepatic Oxidant Defense Pathways.

Hughes, Erin^*,1, Gallagher, Evan¹, ¹ Department of Physiological Sciences, University of Florida, Gainesville, Fl., USA

ABSTRACT- We are currently investigating the effects of in vivo exposure to natural and synthetic estrogens on hepatic detoxification pathways in largemouth bass (Micropterus salmoides), a predatory game fish found throughout the United States. Exposure to estradiol (E₂, 2 mg/kg, i.p.) elicited marked increases in serum vitellogenin levels, as well as initial rate glutathione S-transferase (GST) activities toward 1-chloro-2,4-dinitrobenzene and 5-androstene-3,17-dione. In addition, GST-mediated conjugative activity toward the mutagenic aldehyde 4-hydroxy-2-nonenal was increased in fish exposed to E,₂. Glutathione peroxidase-mediated reduction of cumene hydroperoxide, a function of GST-dependent and selenium-dependent GSH peroxidase activities, was also elevated in E₂-exposed fish. Quinone reductase (QR)-mediated reduction of 2,6-dichloroindophenol was unaffected by E₂. Interestingly, largemouth bass QR activities were not inhibited by dicumarol, a potent inhibitor of DT diaphorase (a major component of quinone reductase activity in rodents). Analysis of GST mRNA and protein expression will be compared to changes in enzymatic activity in bass exposed to E₂, and also to synthetic estrogens. Our results to date indicate that exposure to E₂ may modulate the ability of largemouth bass to detoxify electrophilic substrates. Supported by NIH P42 ES07375

Key words: largemouth bass, glutathione S-transferase, estrogen, oxidative stress