title: In vitro nuclear receptor activity and in vivo gene expression analysis in Murray-Darling rainbowfish (Melanotaenia fluviatilis) after short-term exposure to fluoxetine.
abstract: Fluoxetine (FLX) is one of numerous pharmaceuticals found in treated municipal wastewater discharged to the environment. In the present study, we investigated the effects of short-term (96h) waterborne FLX exposure (1μg/L or 100μg/L) on the expression of selected genes in brain, liver, and gonads of female Murray-Darling rainbowfish (Melanotaenia fluviatilis), a small-bodied teleost of ecotoxicological relevance in the Australasia region. Plasma 17β-estradiol (E2) levels were also determined. In the brain, no significant changes in mRNA levels were observed for the selected genes. In ovaries, 100μg/L FLX caused a 10-fold downregulation of aromatase A (cyp19a1a) mRNA and a 4-fold upregulation of estrogen receptor α (esr1) mRNA levels. In liver, mRNA levels for vitellogenin A (vtga) and choriogenin L (chgl) were downregulated by 50-fold and 18-fold compared with controls, respectively, in response to 100μg/L FLX. Concentrations of E2 in plasma were significantly lower than controls in response to 100μg/L FLX. This could be attributable to a decrease in estrogen biosynthesis as a result of the observed downregulation of cyp19a1a mRNA. To establish whether the observed changes in gene expression could be explained by the modulation of selected nuclear receptors by FLX, we employed panel of reporter gene assays in agonistic and antagonistic modes. Apart from minor activation of ERα after exposure to high concentrations (5μM), FLX did not activate or inhibit the nuclear receptors tested. Further study is required to determine whether the observed downregulation of ovarian aromatase expression and liver estrogen-regulated genes also occurs at environmentally relevant FLX concentrations over longer exposure periods.
authors.affiliation: Commonwealth Scientific and Industrial Research Organisation, Land and Water, Private Mail Bag 2, Glen Osmond, South Australia 5064, Australia. Electronic address: peter.bain@csiro.au.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Bain
authors.affiliation: Peninsular and Marine fish Genetic Resources Centre, National Bureau of Fish Genetic Resources, CMFRI Campus, Post Box No. 1603, Ernakulam North P.O., Kochi 682 018, Kerala, India.
authors.forename: V S
authors.initials: VS
authors.lastname: Basheer
authors.affiliation: Commonwealth Scientific and Industrial Research Organisation, Land and Water, Private Mail Bag 2, Glen Osmond, South Australia 5064, Australia.
authors.forename: Adrienne
authors.initials: A
authors.lastname: Gregg
authors.affiliation: National Bureau of Fish Genetic Resources, Canal Ring Road, P.O. Dilkusha, Lucknow 226 002, Uttar Pradesh, India.
authors.forename: J K
authors.initials: JK
authors.lastname: Jena
authors.affiliation: Commonwealth Scientific and Industrial Research Organisation, Land and Water, Private Mail Bag 2, Glen Osmond, South Australia 5064, Australia.
authors.forename: Anu
authors.initials: A
authors.lastname: Kumar
mesh_terms: D000818:Animals; D001141:Aromatase / Q000235:genetics / Q000378:metabolism; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000097:blood; D005260:Female; D029941:Fish Proteins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D005399:Fishes / Q000235:genetics* / Q000378:metabolism; D005473:Fluoxetine / Q000633:toxicity*; D005786:Gene Expression Regulation / Q000187:drug effects*; D017930:Genes, Reporter; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D010053:Ovary / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D018570:Risk Assessment; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D029941:Fish Proteins; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D014874:Water Pollutants, Chemical; D005473:Fluoxetine; D004958:Estradiol; D001141:Aromatase
keywords: Biomarkers; CALUX; Endocrine disruptors; Freshwater toxicology; Pharmaceuticals; Reporter gene assays; SSRI