Alharthy Khalid M, Albaqami Faisal F, Thornton Cammi, Corrales Jone, Willett Kristine L
Department of BioMolecular Sciences, Divisions of Pharmacology and Environmental Toxicology, School of Pharmacy, University of Mississippi, Mississippi.
Department of BioMolecular Sciences, Divisions of Pharmacology and Environmental Toxicology, School of Pharmacy, University of Mississippi, Mississippi
Toxicol Sci. 2017 Jan;155(1):135-147. doi: 10.1093/toxsci/kfw182. Epub 2016 Sep 14.
Benzo[a]pyrene (BaP) is a ubiquitous environmental contaminant that is both an endocrine disruptor and a carcinogen. Aromatase (CYP19) is a key enzyme in steroidogenesis that is responsible for conversion of androgens to estrogens and thus plays a key role in steroid homeostasis. We hypothesized that some of the adverse outcomes of early developmental exposure to BaP are the result of reduced Cyp19a1b activity. Our goal was to investigate the role of estrogen homeostasis during early development and determine the role of aromatase inhibition as a relevant mechanism in BaP's developmental toxicities. One-cell zebrafish embryos were injected with a Cyp19a1b-morpholino (MO) or control-MO. Other non-injected embryos were exposed to waterborne BaP, fadrozole (a Cyp19 inhibitor), estradiol (E2), BaP + E2, Cyp19a1b MO + E2, or fadrozole + E2 for 96 hours post-fertilization (hpf). Adverse outcomes were compared between treatments, and the ability of E2 co-exposure to rescue each observed dysmorphology was assessed. BaP significantly decreased cyp19a1b gene expression in 96 hpf zebrafish larvae homogenates. Concentrations of E2 in 48 hpf larvae were significantly decreased by BaP, fadrozole and Cyp19a1b-MO. Cumulative mortality of zebrafish larvae was significantly increased following BaP or fadrozole exposure or Cyp19a1b knockdown compared to controls. E2 co-treatment rescued mortality caused by 10 μg/L BaP, 10 μg/L fadrozole, or Cyp19a1b-MO. In a treatment-blinded morphological assessment of larvae at 96 hpf, several phenotypes were negatively impacted by BaP, fadrozole, or Cyp19a1b knockdown and rescued by exogenous E2 co-treatment; these included body length, optic vesicle size, swim bladder inflation, pericardial and abdominal edema, and incidence of normal larval tail shape. Abnormal pectoral fins were caused by BaP exposure only. Uninflated swim bladders were caused by all treatments including E2 alone. Our results indicate that certain BaP-mediated adverse developmental outcomes were mechanistically in accordance with BaP-mediated Cyp19a1b inhibition.
苯并[a]芘（BaP）是一种普遍存在的环境污染物，既是一种内分泌干扰物，也是一种致癌物。芳香化酶（CYP19）是类固醇生成中的关键酶，负责将雄激素转化为雌激素，因此在类固醇稳态中起关键作用。我们假设早期发育暴露于BaP的一些不良后果是Cyp19a1b活性降低的结果。我们的目标是研究早期发育过程中雌激素稳态的作用，并确定芳香化酶抑制作为BaP发育毒性相关机制的作用。将单细胞斑马鱼胚胎注射Cyp19a1b吗啉代寡核苷酸（MO）或对照MO。其他未注射的胚胎在受精后96小时（hpf）暴露于水性BaP、法倔唑（一种Cyp19抑制剂）、雌二醇（E2）、BaP + E2、Cyp19a1b MO + E2或法倔唑 + E2。比较各处理组之间的不良后果，并评估E2共同暴露对每种观察到的畸形的挽救能力。BaP显著降低了96 hpf斑马鱼幼虫匀浆中cyp19a1b基因的表达。BaP、法倔唑和Cyp19a1b-MO显著降低了48 hpf幼虫中E2的浓度。与对照组相比，BaP或法倔唑暴露或Cyp19a1b基因敲低后，斑马鱼幼虫的累积死亡率显著增加。E2联合治疗挽救了由10μg/L BaP、10μg/L法倔唑或Cyp19a1b-MO引起的死亡率。在对96 hpf幼虫进行的治疗盲态形态学评估中，几种表型受到BaP、法倔唑或Cyp19a1b基因敲低的负面影响，并通过外源性E2联合治疗得到挽救；这些表型包括体长、视泡大小、鳔充气、心包和腹部水肿以及正常幼虫尾形的发生率。异常胸鳍仅由BaP暴露引起。未充气的鳔由所有处理引起，包括单独使用E2。我们的结果表明，某些BaP介导的不良发育后果在机制上与BaP介导的Cyp19a1b抑制一致。
