title: Oxidative stress and sex steroid levels in fish following short-term exposure to pulp-mill effluents.
abstract: This study investigates the relationship between oxidative stress and reproductive dysfunction in wild white sucker (Catostomus commersoni) with short-term exposures to pulp-mill effluent. Hepatic oxidative damage, as quantified using 2-thiobarbituric acid-reactive substances (TBARS), was often increased with effluent exposure within 4-8 d, but responses varied by species, sex, and effluent. Fatty acyl-coenzyme A (CoA) oxidase (FAO) and ethoxyresorufin O-deethylase (EROD) activities were also significantly induced between 4 and 8 d of exposure. There were marked species differences in oxidative stress, as TBARS, FAO, and EROD responses in white sucker differed dramatically from those of longnose sucker (Catostomus catostomus) exposed under identical conditions. Exposure for 8 d to pulp-mill effluent delayed ovulation in white sucker, and these delays were independent of changes in circulating testosterone and 17alpha,20beta-dihydroxy-4-pregnen-3-one titers. Evaluations of the effects of pulp mill effluent on in vivo plasma steroid levels and in vitro steroidogenic capacities were compromised due to caging stress. In vivo preexposure to pulp-mill effluent did not reduce in vitro ovarian follicle steroidogenic capacities when exposed to additional reactive oxygen species (ROS) generators. Endocrine and oxidative stress parameters may be interrelated, as the in vivo administration of ferric nitrilotriacetate (Fe(3+)NTA) significantly reduced circulating sex steroids. Administration of a superactive GnRH analog containing a dopamine inhibitor significantly increased TBARS within 24 h, indicating endocrine status is capable of modifying oxidative stress responses. This study provides new knowledge regarding the onset of oxidative stress and changes in reproductive endpoints in fish following pulp-mill effluent exposure.
authors.affiliation: Department of Zoology, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Ken D
authors.initials: KD
authors.lastname: Oakes
authors.forename: L Mark
authors.initials: LM
authors.lastname: Hewitt
authors.forename: Mark E
authors.initials: ME
authors.lastname: McMaster
authors.forename: Craig
authors.initials: C
authors.lastname: Wood
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Munkittrick
authors.forename: Glen J
authors.initials: GJ
authors.lastname: Van Der Kraak
mesh_terms: D000818:Animals; D003531:Cypriniformes / Q000502:physiology*; D019363:Cytochrome P-450 CYP1A1 / Q000494:pharmacology; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D007220:Industrial Waste; D008297:Male; D006080:Ovarian Follicle / Q000254:growth & development; D010060:Ovulation / Q000187:drug effects; D018384:Oxidative Stress; D010209:Paper; D017382:Reactive Oxygen Species / Q000032:analysis; D012098:Reproduction; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D012739:Gonadal Steroid Hormones; D007220:Industrial Waste; D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D019363:Cytochrome P-450 CYP1A1