Toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in developing red seabream (Pagrus major) embryo: an association of morphological deformities with AHR1, AHR2 and CYP1A expressions.
Toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in developing red seabream (Pagrus major) embryo: an association of morphological deformities with AHR1, AHR2 and CYP1A expressions.
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DOI：
10.1016/j.aquatox.2006.08.006
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发表时间：
2006-11
影响因子：
4.5
通讯作者：
Masanobu Yamauchi;Eun-Young Kim;H. Iwata;Y. Shima;S. Tanabe
中科院分区：
文献类型：
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作者：
Masanobu Yamauchi;Eun-Young Kim;H. Iwata;Y. Shima;S. Tanabe
二恶英类化合物（如2，3，7，8-四氯二苯并对二恶英（TCDD））的毒性主要由芳香烃受体（AHR）介导，该受体调控包括细胞色素P4501 A（CYP 1A）在内的多个靶基因。硬骨鱼具有至少两个不同的AHR，是生命早期对TCDD最敏感的脊椎动物之一。然而，鱼类多种AHRs的生理和毒理作用尚未完全了解，特别是在海洋鱼类。要了解AHR是负责TCDD毒性的海洋鱼类，我们的特点是早期生命阶段的毒性相关的表达AHRs和CYP 1A的红海鸟（真鲷）。用0-100μg/L TCDD处理受精后10 h的胚胎80 min。TCDD剂量依赖性地引起发育毒性，包括死亡、卵黄囊水肿、身体发育迟缓、脊柱畸形、心率降低、吻部缩短、鳍、心脏和下颌发育不全。有趣的是，出血和心包水肿，典型的TCDD发育缺陷，注意到在其他鱼类物种，没有发现在红海鸟，直到测试结束。卵黄囊水肿、鳍发育不全和脊柱畸形的ECegg 50分别为170、240和340 pg/g。其LC_（egg）为360 pg/g胚胎，是对TCDD毒性最敏感的鱼类之一。rsAHR 1、rsAHR 2和CYP 1A mRNA在不同发育阶段的表达水平也进行了测定。TCDD暴露后rsAHR 2 mRNA表达呈剂量依赖性增加，而rsAHR 1 mRNA水平无明显变化。在用最高剂量处理的胚胎中，通过两步实时PCR测量的rsAHR 2 mRNA水平比rsAHR 1高30倍。TCDD处理的胚胎中rsAHR 2和CYP 1A mRNA的时间模式相似，代表rsAHR 2和CYP 1A mRNA水平之间显著正相关，但rsAHR 1和CYP 1A之间不相关。比较TCDD诱导的AHRs和CYP 1A表达的时间趋势以及发育毒性，在TCDD毒性表现的最大发生率出现之前检测到rsAHR 2和CYP 1A mRNA的最高表达。这些结果表明，rsAHR 2可能主要参与CYP 1A的转录调控，并且一些TCDD缺陷依赖于rsAHR 2和/或rsAHR 2-CYP 1A信号通路的改变，这些信号通路通过其表达水平来控制。
The toxicity of dioxins such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is mainly mediated by the aryl hydrocarbon receptor (AHR), which regulates the multiple target genes including cytochrome P4501A (CYP1A). In general, bony fishes, which possess at least two distinct AHRs are one of the most sensitive vertebrates to TCDD in early life stage. However, the physiological and toxicological roles of piscine multiple AHRs are not fully understood, especially in marine fish. To understand which AHR is responsible for TCDD toxicity in a marine fish species, we characterized the early life stage toxicity related to the expression of AHRs and CYP1A in red seabream (Pagrus major). The embryos at 10h post-fertilization (hpf) were treated with 0–100μg/L TCDD for 80min waterborne exposure. TCDD dose-dependently elicited developmental toxicities including mortality, yolk sac edema, retarded body growth, spinal deformity, reduced heart rate, shortened snout, underdeveloped fin, heart, and lower jaw. Intriguingly, hemorrage and pericardium edema, typical TCDD developmental defects noticed in other fish species, were not found in red seabream until test termination. The ECegg50s for yolk sac edema, underdeveloped fin, and spinal deformity were 170, 240, and 340pg/g, respectively. The LCegg50 was 360pg/g embryo, indicating that this species is one of the most sensitive fishes to TCDD toxicity. The expression levels of rsAHR1, rsAHR2 and CYP1A mRNAs were also determined in different developmental stages. The rsAHR2 mRNA expression dose-dependently increased following TCDD exposure, while rsAHR1 mRNA level was not altered. Level of rsAHR2 mRNA measured by two-step real-time PCR was 30 times higher than rsAHR1 in embryos treated with the highest dose. Temporal patterns of rsAHR2 and CYP1A mRNAs were similar in TCDD-treated embryos, representing a significant positive correlation between rsAHR2 and CYP1A mRNA levels, but not between rsAHR1 and CYP1A. In comparison of temporal trends of TCDD-induced AHRs and CYP1A expression, and developmental toxicities, the highest expression of rsAHR2 and CYP1A mRNA were detected prior to the appearance of maximal incidence of TCDD toxic manifestations. These results suggest that rsAHR2 may be dominantly involved in the transcriptional regulation of CYP1A, and several TCDD defects are dependent on the alteration of rsAHR2 and/or rsAHR2-CYP1A signaling pathway that is controlled through their expression levels.