title: A proposed multigeneration protocol for Japanese medaka (Oryzias latipes) to evaluate effects of endocrine disruptors.
abstract: Definitive data on reproductive impairment of chronically exposed populations may be required to assess the appropriateness of the existing test methods for hazard identification and prioritization of endocrine modulators. Multigeneration toxicity testing protocols for wildlife receptors are lacking. To help address this gap we describe a multigeneration fish assay using the freshwater fish, Japanese medake (Oryzias latipes). This test species has been used for the evaluation of carcinogenic, teratogenic and reproductive effects and is sensitive to estrogen exposure producing ovo-testis, altered biochemical parameters and phenotypic characteristics. Due to the short life cycle, a multigeneration test with medaka can be conducted in 1 year. Endpoints evaluated include: survival, growth, sex ratio, fecundity, embryonic lesion occurrence, embryonic stage development, gonadal and hepatic somatic indices, histopathology and biochemical parameters. As new endpoints are developed they can be incorporated into the protocol. Results of a positive control (17 beta-estradiol) study are presented to give an indication of the baseline associated with various test endpoints and to highlight the importance of nutrition in the experimental design. 17 beta-Estradiol treatment induced vitellogenin production in male and female medaka, feminized males, and disrupted egg production. The proposed protocol provides researchers with an effective multigeneration fish test that can be used to examine potential effects of stressors at the population, individual, cellular and subcellular level.
authors.affiliation: Joint Graduate Program in Toxicology, Rutgers, State University of New Jersey, Piscataway 08901, USA. patyna@aesop.rutgers.edu
authors.forename: P J
authors.initials: PJ
authors.lastname: Patyna
authors.forename: R A
authors.initials: RA
authors.lastname: Davi
authors.forename: T F
authors.initials: TF
authors.lastname: Parkerton
authors.forename: R P
authors.initials: RP
authors.lastname: Brown
authors.forename: K R
authors.initials: KR
authors.lastname: Cooper
mesh_terms: D000818:Animals; D004032:Diet; D004702:Endocrine Glands / Q000187:drug effects*; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000008:administration & dosage / Q000633:toxicity*; D004958:Estradiol / Q000008:administration & dosage / Q000633:toxicity; D005260:Female; D005262:Feminization / Q000139:chemically induced; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009866:Oogenesis / Q000187:drug effects; D009990:Oryzias / Q000254:growth & development / Q000502:physiology; D013739:Testosterone / Q000378:metabolism; D014819:Vitellogenins / Q000096:biosynthesis
chemical_list: D004785:Environmental Pollutants; D014819:Vitellogenins; D013739:Testosterone; D004958:Estradiol