College of Fisheries, Huazhong Agricultural University, Wuhan 430070, PR China.
Donghu Experimental Station of Lake Ecosystems, State Key Laboratory for Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China.
Ecotoxicol Environ Saf. 2017 May;139:27-35. doi: 10.1016/j.ecoenv.2017.01.025.
Recent studies have documented that microcystins (MCs) have potential toxic effects on growth and reproduction in fish. However, no systematic data exist on whether MCs cause gonadal development retardation through disrupting the growth hormone/insulin-like growth factors (GH/IGFs) system. To this end, zebrafish hatchlings (5 d post-fertilization) were exposed to 0, 0.3, 3 and 30µg/L microcystin-LR (MC-LR) for 90 d until they reached sexual maturity. Life-cycle exposure to MC-LR caused delayed ovarian maturation and sperm development along with ultrapathological lesions in the brain and liver. Moreover, the retarded gonadal development was accompanied by an inhibition of the GH/IGFs system, which was characterized by significant decreases in the transcriptional levels of brain gh (males only), hepatic igf2a and igf2b as well as gonadal igf1 (males only), igf3 and igf2r. These findings for the first time point to the influence of MC-LR on fish gonadal development via the GH/IGFs system. Also, sex-differential impairments suggested that gonadal development of males is more vulnerable than that of female to MC-LR. Our results provide evidence that MC-LR at environmentally relevant concentrations is able to induce impairments on fish gonadal development.
最近的研究记录表明，微囊藻毒素（MCs）对鱼类的生长和繁殖具有潜在的毒性作用。然而，目前尚无系统数据表明 MCs 是否通过破坏生长激素/胰岛素样生长因子（GH/IGFs）系统导致性腺发育迟缓。为此，本研究采用斑马鱼幼鱼（受精后 5 天）进行 90 天的暴露实验，暴露浓度分别为 0、0.3、3 和 30μg/L 的微囊藻毒素-LR（MC-LR），直至其达到性成熟。MC-LR 的生命周期暴露导致卵巢成熟和精子发育延迟，并伴有脑和肝的超微病理损伤。此外，性腺发育迟缓伴随着 GH/IGFs 系统的抑制，其特征是脑 gh（仅雄性）、肝 igf2a 和 igf2b 以及性腺 igf1（仅雄性）、igf3 和 igf2r 的转录水平显著降低。这些发现首次表明，MC-LR 通过 GH/IGFs 系统对鱼类性腺发育产生影响。此外，性别差异损伤表明，与雌性相比，雄性的性腺发育对 MC-LR 更为敏感。我们的研究结果提供了证据，表明在环境相关浓度下，MC-LR 能够诱导鱼类性腺发育损伤。
