title: Microcystin-RR exposure results in growth impairment by disrupting thyroid endocrine in zebrafish larvae.
abstract: Recent studies have shown that cyanobacteria-derived microcystins (MCs) have the potential to disrupt endocrine systems. However, the effects of microcystin-RR (MC-RR) and their underlying mechanisms are poorly resolved in fish. In this study, MC-RR exposure through submersion caused serious developmental toxicity, such as growth delay and depressed heart rates in zebrafish larvae. We also detected decreased levels of thyroid hormones (THs), suggesting that MC-RR-triggered thyroid endocrine disruption might contribute to the growth impairment observed in developing zebrafish. To further our understanding of mechanisms of MC-RR-induced endocrine toxicity, quantitative real-time PCR (QPCR) analysis was performed on hypothalamic-pituitary-thyroid (HPT) axis related genes, i.e., corticotropin-releasing factor (CRF), thyroid-stimulating hormone (TSH), sodium/iodide symporter (NIS), thyroglobulin (TG), thyroid receptors (TRα and TRβ) and iodothyronine deiodinases (Dio1 and Dio2), of developing zebrafish embryos exposed to 0, 0.3, 1.0 or 3.0mgL(-1) MC-RR until 96h post-fertilization. Our results showed that transcription pattern of HPT axis related genes were greatly changed by MC-RR exposure, except TG gene. Furthermore, western blot was used to validate the results of gene expression. The results showed protein synthesis of TG was not affected, while that of NIS was significantly up-regulated, which are in accordance with gene expression. The overall results indicated that exposure to MC-RR can induce developmental toxicity, which might be associated with thyroid endocrine disruption in developing zebrafish larvae.
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing 210008, China.
authors.forename: Liqiang
authors.initials: L
authors.lastname: Xie
authors.affiliation: Institute of Agricultural Quality Standards & Testing Technology, Hubei Academy of Agricultural Sciences, Wuhan 430064, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Yan
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Liqin
authors.initials: L
authors.lastname: Yu
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Jianghua
authors.initials: J
authors.lastname: Wang
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China. Electronic address: ligy2001@163.com.
authors.forename: Guangyu
authors.initials: G
authors.lastname: Li
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China. Electronic address: chennan@mail.hzau.edu.cn.
authors.forename: Nan
authors.initials: N
authors.lastname: Chen
authors.affiliation: Robert B. Annis Water Resources Institute, Grand Valley State University, 740 West Shoreline Drive, Muskegon, MI 49441, USA.
authors.forename: Alan D
authors.initials: AD
authors.lastname: Steinman
mesh_terms: D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000235:genetics; D052244:Endocrine Disruptors / Q000633:toxicity; D004703:Endocrine System / Q000187:drug effects*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D007453:Iodide Peroxidase / Q000235:genetics; D008387:Marine Toxins; D052998:Microcystins / Q000633:toxicity*; D013961:Thyroid Gland / Q000187:drug effects; D037042:Thyroid Hormone Receptors beta / Q000235:genetics; D013963:Thyroid Hormones / Q000235:genetics; D013972:Thyrotropin / Q000235:genetics; D014874:Water Pollutants, Chemical / Q000633:toxicity; D015027:Zebrafish / Q000254:growth & development*
chemical_list: D052244:Endocrine Disruptors; D008387:Marine Toxins; D052998:Microcystins; D037042:Thyroid Hormone Receptors beta; D013963:Thyroid Hormones; D014874:Water Pollutants, Chemical; D013972:Thyrotropin; D003346:Corticotropin-Releasing Hormone; C063855:microcystin RR; D007453:Iodide Peroxidase
keywords: Developing zebrafish; Growth impairment; Hypothalamic–pituitary–thyroid axis; MC-RR