title: Responses of the zebrafish hypothalamic-pituitary-gonadal-liver axis PCR array to prochloraz are dependent on timing of sampling.
abstract: A PCR array, based on expression of genes along the hypothalamic-pituitary-gonadal-liver (HPGL) axis of fish, has been suggested as a useful method for screening of endocrine-disrupting chemicals (EDCs). However, effects of circadian rhythm on responses of the HPGL axis to exposure to chemicals were unknown. In this study, profiles of expression of genes along the HPGL axis and concentrations of 17β-estradiol (E2) in blood plasma of female zebrafish were compared at two sampling times of day (8:00 AM and 7:00 PM). Prochloraz (PCZ) was selected as a model chemical to evaluate differences in responses of the HPGL axis at these two times of day. Profiles of responses of concentrations of E2 in plasma and expressions of genes along the HPGL axis genes were different between the two times of sampling. Concentrations of E2 were less, and abundances of mRNA for several genes along the HPGL axis were significantly greater or lesser when samples were collected at 7:00 PM than they were when samples were collected at 8:00 AM. Exposure to three concentrations of PCZ (3, 30 or 300μg/L) for 48h resulted in significantly lesser concentrations of plasma E2 and caused compensatory up-regulation of genes included in hypothalamus, pituitary and ovary. Expressions of genes along the HPGL were more responsive to PCZ at 8:00 AM than they were when samples were collected at 7:00 PM. Correlations among parameters in samples collected at the two times indicated the effects might be due to different concentrations of E2 in plasma due to exposure to PCZ.
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Dang
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Jianghua
authors.initials: J
authors.lastname: Wang
authors.affiliation: School of Biological Sciences, University of Hong Kong, Hong Kong Special Administrative Region, China; Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada; State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China.
authors.forename: John P
authors.initials: JP
authors.lastname: Giesy
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China; Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province, Hunan Changde 415000, China. Electronic address: liuchunshengidid@126.com.
authors.forename: Chunsheng
authors.initials: C
authors.lastname: Liu
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology; D052244:Endocrine Disruptors / Q000633:toxicity; D004703:Endocrine System / Q000187:drug effects*; D004958:Estradiol / Q000235:genetics / Q000378:metabolism; D005260:Female; D029941:Fish Proteins / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D006066:Gonads / Q000187:drug effects; D007031:Hypothalamus / Q000187:drug effects; D007093:Imidazoles / Q000633:toxicity*; D008099:Liver / Q000187:drug effects; D010053:Ovary / Q000187:drug effects; D010902:Pituitary Gland / Q000187:drug effects; D016133:Polymerase Chain Reaction; D014874:Water Pollutants, Chemical / Q000633:toxicity; D015027:Zebrafish / Q000502:physiology*
chemical_list: D052244:Endocrine Disruptors; D029941:Fish Proteins; D007093:Imidazoles; D014874:Water Pollutants, Chemical; D004958:Estradiol; C045362:prochloraz
keywords: Compensatory response; Expressions of genes; HPGL axis; PCR array; Prochloraz