title: Subacute microcystin-LR exposure alters the metabolism of thyroid hormones in juvenile zebrafish (Danio Rerio).
abstract: Microcystin-LR (MC-LR) has been detected extensively in the aquatic environment and has the potential to disturb the thyroid endocrine system. However, limited information is available on the effects of subacute MC-LR exposure on fish thyroid hormone (TH) metabolism. In the present study, juvenile zebrafish (Danio rerio) were exposed to MC-LR at environmentally relevant concentrations (0, 1, 5, and 25 μg/L) for 28 days. Whole-body TH content and thyroid follicle histology were used as direct endpoints to assess thyroid disruption. The activities of iodothyronine deiodinases (IDs) and the transcription of selected genes associated with TH synthesis were also investigated to study the underlying mechanisms of endocrine disruption. Exposure of zebrafish to MC-LR significantly increased whole-body thyroxine (T4) content but decreased whole-body triiodothyronine (T3) content. We also observed hypertrophy and hyperplasia of the thyroid follicle epithelial cells, as well as up-regulation of corticotropin-releasing hormone (CRH), thyroid-stimulating hormone (TSH), thyroid peroxidase (TPO), and transthyretin (TTR) genes. The decreases in ID1 and ID2 activities coupled with an increase in ID3 activity were observed in MC-LR treatment groups. These results demonstrate that exposure to MC-LR at environmental concentrations results in the disturbance of TH homeostasis by disrupting the synthesis and conversion of THs.
authors: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China. liuzidong0202@163.com.|Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China. liuzidong0202@163.com.|Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, China. liuzidong0202@163.com.
authors: Zidong
authors: Z
authors: Liu
authors: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China. tangrong@mail.hzau.edu.cn.|Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China. tangrong@mail.hzau.edu.cn.|Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, China. tangrong@mail.hzau.edu.cn.
authors: Rong
authors: R
authors: Tang
authors: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China. ldp@mail.hzau.edu.cn.|Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China. ldp@mail.hzau.edu.cn.|Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, China. ldp@mail.hzau.edu.cn.|Life Science College, Hunan University of Arts and Science, Changde 415000, China. ldp@mail.hzau.edu.cn.
authors: Dapeng
authors: D
authors: Li
authors: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China. huqinggw@webmail.hzau.edu.cn.|Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China. huqinggw@webmail.hzau.edu.cn.|Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, China. huqinggw@webmail.hzau.edu.cn.
authors: Qing
authors: Q
authors: Hu
authors: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China. wyingale@gmail.com.
authors: Ying
authors: Y
authors: Wang
mesh_terms: D000818:Animals; D000458:Cyanobacteria / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D052244:Endocrine Disruptors / Q000633:toxicity*; D004784:Environmental Monitoring; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008387:Marine Toxins; D052998:Microcystins / Q000633:toxicity*; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D013963:Thyroid Hormones / Q000235:genetics / Q000378:metabolism*; D059467:Transcriptome / Q000187:drug effects; D015027:Zebrafish / Q000254:growth & development / Q000378:metabolism*
chemical_list: D052244:Endocrine Disruptors; D008387:Marine Toxins; D052998:Microcystins; D013963:Thyroid Hormones; C057862:cyanoginosin LR
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