title: Life-cycle exposure to microcystin-LR interferes with the reproductive endocrine system of male zebrafish.
abstract: Recently, MC-LR reproductive toxicity drew great attention. Limited information was available on endocrine-disrupting effects of MC-LR on the reproduction system in fish. In the present study, zebrafish hatchlings (5 d post-fertilization) were exposed to 0, 0.3, 3 and 30μg/L MC-LR for 90 d until they reached sexual maturity. Male zebrafish were selected, and changes in growth and developmental parameters, testicular histological structure as well as the levels of gonadal steroid hormones were studied along with the related-gene transcriptional responses in the hypothalamic-pituitary-gonadal axis (HPG-axis). The results, for the first time, show a life cycle exposure to MC-LR causes growth inhibition, testicular damage and delayed sperm maturation. A significant decrease in T/E2 ratio indicated that MC-LR disrupted sex steroid hormones balance. The changes in transcriptional responses of HPG-axis related genes revealed that MC-LR promoted the conversion of T to E2 in circulating blood. It was also noted that vtg1 mRNA expression in the liver was up-regulated, which implied that MC-LR could induce estrogenic-like effects at environmentally relevant concentrations and long-term exposure. Our findings indicated that a life cycle exposure to MC-LR causes endocrine disruption with organic and functional damage of the testis, which might compromise the quality of life for the survivors and pose a potent threat on fish reproduction and thus population dynamics in MCs-contaminated aquatic environments.
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, PR China; Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, PR China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, PR China.
authors.forename: Yujing
authors.initials: Y
authors.lastname: Su
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, PR China; Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, PR China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, PR China. Electronic address: foreverlili78@mail.hzau.edu.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, PR China; Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, PR China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, PR China.
authors.forename: Jie
authors.initials: J
authors.lastname: Hou
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, PR China; Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, PR China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, PR China.
authors.forename: Ning
authors.initials: N
authors.lastname: Wu
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, PR China; Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, PR China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, PR China.
authors.forename: Wang
authors.initials: W
authors.lastname: Lin
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, PR China; Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, PR China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, PR China.
authors.forename: Guangyu
authors.initials: G
authors.lastname: Li
mesh_terms: D000818:Animals; D004703:Endocrine System / Q000187:drug effects* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D004958:Estradiol / Q000097:blood; D008018:Life Cycle Stages; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008387:Marine Toxins; D052998:Microcystins / Q000633:toxicity*; D012333:RNA, Messenger / Q000378:metabolism; D012098:Reproduction / Q000187:drug effects; D013737:Testis / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013739:Testosterone / Q000097:blood; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish / Q000502:physiology; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D008387:Marine Toxins; D052998:Microcystins; D012333:RNA, Messenger; D014874:Water Pollutants, Chemical; D029961:Zebrafish Proteins; D013739:Testosterone; D004958:Estradiol; C057862:cyanoginosin LR
keywords: Endocrine-disrupting effect; Hypothalamic-pituitary-gonadal axis; Microcystin-LR; Reproductive toxicity; Sex steroid hormone