Department of Pharmacology, Weill Cornell Medical College, New York, NY.
Drug Metab Dispos. 2014 Feb;42(2):294-300. doi: 10.1124/dmd.113.055368. Epub 2013 Dec 5.
The environmental toxin and carcinogen 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) binds and activates the transcription factor aryl hydrocarbon receptor (AHR), inducing CYP1 family cytochrome P450 enzymes. CYP1A2 and its avian ortholog CYP1A5 are highly active arachidonic acid epoxygenases. Epoxygenases metabolize arachidonic acid to four regioisomeric epoxyeicosatrienoic acids (EETs) and selected monohydroxyeicosatetraenoic acids (HETEs). EETs can be further metabolized by epoxide hydrolases to dihydroxyeicosatrienoic acids (DHETs). As P450-arachidonic acid metabolites affect vasoregulation, responses to ischemia, inflammation, and metabolic disorders, identification of their production in vivo is needed to understand their contribution to biologic effects of TCDD and other AHR activators. Here we report use of an acetonitrile-based extraction procedure that markedly increased the yield of arachidonic acid products by lipidomic analysis over a standard solid-phase extraction protocol. We show that TCDD increased all four EETs (5,6-, 8,9-, 11,12-, and 14,15-), their corresponding DHETs, and 18- and 20-HETE in liver in vivo and increased 5,6-EET, the four DHETs, and 18-HETE in heart, in a chick embryo model. As the chick embryo heart lacks arachidonic acid-metabolizing activity, the latter findings suggest that arachidonic acid metabolites may travel from their site of production to a distal organ, i.e., heart. To determine if the TCDD-arachidonic acid-metabolite profile could be altered pharmacologically, chick embryos were treated with TCDD and the soluble epoxide hydrolase inhibitor 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA). Cotreatment with AUDA increased hepatic EET-to-DHET ratios, indicating that the in vivo profile of P450-arachidonic acid metabolites can be modified for potential therapeutic intervention.
环境毒素和致癌物质 2,3,7,8-四氯二苯并对二恶英（TCDD，二恶英）与转录因子芳烃受体（AHR）结合并使其激活，诱导 CYP1 家族细胞色素 P450 酶。CYP1A2 和其禽类同源物 CYP1A5 是高度活跃的花生四烯酸环加氧酶。环加氧酶将花生四烯酸代谢为四种区域异构体环氧二十碳三烯酸（EETs）和选定的单羟基二十碳四烯酸（HETEs）。EETs 可进一步被环氧化物水解酶代谢为二羟基二十碳三烯酸（DHETs）。由于 P450-花生四烯酸代谢物影响血管调节、对缺血、炎症和代谢紊乱的反应，因此需要确定其在体内的产生，以了解其对 TCDD 和其他 AHR 激活剂的生物学效应的贡献。在这里，我们报告了一种基于乙腈的提取程序的使用，该程序通过脂质组学分析大大提高了脂类产物中花生四烯酸产物的产量，超过了标准固相萃取方案。我们表明，TCDD 增加了所有四种 EETs（5,6-，8,9-，11,12-和 14,15-）、它们相应的 DHETs 以及 18-和 20-HETE 在体内的肝脏中，并增加了 5,6-EET、四种 DHETs 和 18-HETE 在鸡胚模型中的心脏中。由于鸡胚心脏缺乏花生四烯酸代谢活性，后一种发现表明，花生四烯酸代谢物可能从其产生部位运输到远端器官，即心脏。为了确定 TCDD-花生四烯酸代谢物谱是否可以通过药理学改变，鸡胚用 TCDD 和可溶性环氧化物水解酶抑制剂 12-（3-金刚烷-1-基-脲基）-十二烷酸（AUDA）处理。与 AUDA 共同处理增加了肝 EET 对 DHET 的比值，表明 P450-花生四烯酸代谢物的体内谱可以进行修饰以进行潜在的治疗干预。
