Nannelli Annalisa, Rossignolo Francesco, Tolando Roberto, Rossato Paolo, Longo Vincenzo, Gervasi P Giovanni
Istituto di Fisiologia Clinica, CNR, via Moruzzi 1, 56100 Pisa, Italy.
Toxicology. 2009 Nov 30;265(3):69-79. doi: 10.1016/j.tox.2009.09.010. Epub 2009 Sep 26.
The constitutive and inducible expression of aryl hydrocarbon receptor (AhR) and of the AhR-regulated genes coding for CYP1A1, CYP1A2, CYP1B1, CYP2S1, and Nrf2 was investigated by real-time or traditional PCR in cerebral areas (cortex, cerebellum, midbrain, and hippocampus), blood-brain interfaces (meninges and brain microvessels) and liver obtained from control pigs and from pigs treated with beta-naphthoflavone (betaNF), a potent AhR agonist. The enzymatic activities of ethoxyresorufin-O-deethylase (EROD), and methoxyresorufin-O-deethylase (MEROD), marker for CYP1A1 and CYP1A2, the GST and various antioxidant enzymes (catalase, superoxide dismutase, GSSG-reductase, and GSH-peroxidase) were also determined in the same CNS regions. The AhR, CYP1A1, CYP1A2, CYP1B1, Nrf2 mRNAs were detected, although at different extent, in all the CNS regions, while CYP2S1 mRNA was detected only in midbrain. In the blood-brain interfaces, the constitutive basal expression of AhR and CYP1A1 was comparable to the hepatic one and even higher for CYP1B1 and Nrf2. The treatment with betaNF determined the induction of CYP1A1 and 1B1 (but not of AhR, CYP1A2, and Nrf2) mRNA levels in various CNS areas; notably, CYP1A1 mRNA was increased to about 300-fold in the microvessels. The analysis of enzymatic activities revealed that EROD, but not MEROD, was induced in microsomes but not in mitochondria of all the CNS areas. However, the mitochondrial EROD activities were comparable (in midbrain, meninges) or higher (in cortex, cerebellum, hippocampus) than the microsomal ones, suggesting an important metabolic function of CYP1A1 in this subcellular localization. The activities of GST and antioxidant enzymes were detected in all CNS tissues, with levels lower than the hepatic ones, but found quite evenly distributed and marginally affected by betaNF treatment. The high expression of metabolic enzymes found in blood-brain interfaces could represent a very important defence toward toxins of CNS.
通过实时或传统PCR，在来自对照猪以及用强效芳烃受体（AhR）激动剂β-萘黄酮（βNF）处理的猪的脑区（皮层、小脑、中脑和海马体）、血脑界面（脑膜和脑微血管）和肝脏中，研究了AhR以及编码CYP1A1、CYP1A2、CYP1B1、CYP2S1和Nrf2的AhR调控基因的组成型和诱导型表达。还在相同的中枢神经系统区域测定了乙氧异吩唑酮-O-脱乙基酶（EROD）和甲氧基异吩唑酮-O-脱乙基酶（MEROD）的酶活性，它们分别是CYP1A1和CYP1A2的标志物，以及谷胱甘肽S-转移酶（GST）和各种抗氧化酶（过氧化氢酶、超氧化物歧化酶、谷胱甘肽二硫化物还原酶和谷胱甘肽过氧化物酶）。在所有中枢神经系统区域均检测到了AhR、CYP1A1、CYP1A2、CYP1B1、Nrf2的mRNA，不过程度不同，而CYP2S1的mRNA仅在中脑检测到。在血脑界面，AhR和CYP1A1的组成型基础表达与肝脏中的相当，而CYP1B1和Nrf2的甚至更高。用βNF处理可诱导不同中枢神经系统区域中CYP1A1和1B1（但不包括AhR、CYP1A2和Nrf2）的mRNA水平；值得注意的是，微血管中CYP1A1的mRNA增加到约300倍。酶活性分析表明，所有中枢神经系统区域的微粒体中EROD被诱导，但MEROD未被诱导，线粒体中未诱导。然而，线粒体EROD活性与微粒体相当（中脑、脑膜）或更高（皮层、小脑、海马体），这表明CYP1A1在该亚细胞定位中具有重要的代谢功能。在所有中枢神经系统组织中均检测到了GST和抗氧化酶的活性，其水平低于肝脏中的，但分布相当均匀，且受βNF处理的影响较小。在血脑界面发现的代谢酶的高表达可能代表了对中枢神经系统毒素的非常重要的防御。
