Single and combined exposure of microcystin-LR and nitrite results in reproductive endocrine disruption via hypothalamic-pituitary-gonadal-liver axis
Single and combined exposure of microcystin-LR and nitrite results in reproductive endocrine disruption via hypothalamic-pituitary-gonadal-liver axis
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微囊藻毒素-LR 和亚硝酸盐的单独和联合暴露会通过下丘脑-垂体-性腺-肝脏轴导致生殖内分泌干扰
DOI：
10.1016/j.chemosphere.2018.08.049
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发表时间：
2018
期刊：
影响因子：
8.8
通讯作者：
Zhang Xuezhen
中科院分区：
文献类型：
--
作者：
Lin Wang;Guo Honghui;Li Yufen;Wang Lingkai;Zhang D;an;Hou Jie;Wu Kueyang;Li Li;Li Dapeng;Zhang Xuezhen
微囊藻水华降解释放的微囊藻毒素-LR(MC-LR)通常与一种称为亚硝酸盐的化学物质共存，对水生生物造成严重危害。为了评价MC-LR和亚硝酸盐单独及联合作用对雄性斑马鱼生殖内分泌系统的影响，采用完全析因试验，将MC-LR(0，3，30 μg/L)和亚硝酸盐(0，2，20 mg/L)的9种处理组合暴露于成年雄性斑马鱼30 d，结果表明，MC-LR和亚硝酸盐均引起生长抑制、性腺指数下降以及睾丸细胞间隙增宽和生精上皮变性等浓度依赖性效应。MC-LR和亚硝酸盐联合染毒组小鼠睾丸病理改变与单独染毒组相似，但比单因素染毒组严重。同时，MC-LR或亚硝酸盐单独暴露可通过下调下丘脑-垂体-性腺-肝轴(HPGL轴)基因(GnRH2、LHR2、β、AR、LHR)的表达而显著降低T水平，且MC-LR与亚硝酸盐之间存在显著的交互作用。相反，随着MC-LR浓度的增加，E2水平以及cyp19a1b、cyp19a1a和vtg1的转录水平均表现出明显的诱导作用，表明MC-LR具有雌激素样作用。我们的研究结果表明，MC-LR和亚硝酸盐的共同暴露通过干扰雄性鱼类的HPGL轴而协同地导致生殖功能障碍，这促使我们更多地关注由于有毒蓝藻水华的广泛出现而对鱼类繁殖甚至种群动态造成的潜在风险。
Microcystin-LR (MC-LR) released byMicrocystisblooms degradation usually co-exists with a chemical called nitrite, posing a serious harm to aquatic organisms. To assess the single and combined effects of MC-LR and nitrite on the reproductive endocrine system, a fully factorial experiment was designed and adult male zebrafish (Danio rerio) were exposed to 9 treatment combinations of MC-LR (0, 3, 30 μg/L) and nitrite (0, 2, 20 mg/L) for 30 d. The results showed that both MC-LR and nitrite caused concentration-dependent effects including the growth inhibition, decreased gonad index as well as testicular injuries with widen intercellular spaces and seminiferous epithelium deteriorations. And testicular pathological changes in the co-exposure groups of MC-LR and nitrite were similar but more serious than those in single-factor exposure groups. Concurrently, exposure to MC-LR or nitrite alone could significantly decrease T levels by downregulating gene expressions (gnrh2,lhβ,ar,lhr) in the hypothalamic-pituitary-gonadal-liver-axis (HPGL-axis), and there were significant interactions between MC-LR and nitrite on them. In contrast, E2 levels as well as transcriptional levels ofcyp19a1b,cyp19a1aandvtg1showed significant inductions with increasing MC-LR concentrations, indicating an estrogen-like effect of MC-LR. Our findings illustrated that co-exposure of MC-LR and nitrite synergistically cause reproductive dysfunction by interfering with the HPGL axis in male fish, which prompt us to focus more on the potential risks in fish reproduction and even population dynamics due to the wide occurrence of toxic cyanobacterial blooms.