Effect of Carbendazim on Cytochrome P450s in Rats

貝芬替是廣泛且具有系統性的殺菌劑，用來控制植物發霉、腐爛和枯萎。貝芬替和相關的benzimidazoles在大鼠中顯示出具有生殖毒性和內分泌干擾作用。細胞色素P450在代謝上是屬於第一級的酵素系統，對藥物、致癌物、類固醇類的賀爾蒙和環境汙染物的代謝功能。本研究的主要目的是探討貝芬替在大鼠肝、腎、肺和睪丸細胞色素P450及抗氧化酵素的調控。雄性大鼠以腹腔注射貝芬替，處理劑量分別為10、50、100 mg/kg，1天1次進行4天，造成睪丸的精子數目呈劑量效應的下降關係。在肝臟微粒體中，貝芬替處理增加P450 content、NADPH-cytochrome P450 reductase、7-ethoxyresorufin O-deethylase (EROD)、methoxyresorufin O-demethylase (MROD)、pentoxyresorufin O-dealkylase和7-ethoxycoumarin O-deethylase (ECOD)酵素活性。在腎臟微粒體中，貝芬替增加P450 content、EROD和ECOD酵素活性。在肺臟微粒體中，貝芬替處理增加EROD酵素活性。在睪丸微粒體中，貝芬替增加NADPH-cytochrome P450 reductase 酵素活性。貝芬替增加肝臟細胞液中的glutathione S-transferase (GST)、catalase酵素活性以及在睪丸細胞液中的GST和superoxide dismutase酵素活性。此殺菌劑會降低腎臟中的glutathione content和睪丸組織中的脂質過氧化。口服400 mg/kg 貝芬替7天會增加肝臟微粒體中MROD酵素活性。在西方點墨法和RT-PCR分析中，在肝臟組織中CYP1A1/2和CYP2B的蛋白量和mRNA皆增加；在腎臟和肺臟中則是CYP1A1的蛋白量和mRNA增加。在目前的研究中發現，貝芬替是大鼠中CYP1A1/2和CYP2B的誘導物。在酵素活性上經貝芬替顯著誘導的細胞色素P450需要再進一步的探討。Carbendazim (methyl-2-benzimidazole carbamate) is a broad spectrum and systemic fungicide for the control of molds, rots, and blight. Carbendazim and related benzimidazoles show marked reproductive toxicity and endocrine-disrupting activity in rats. Cytochrome P450 (CYP) is the primary enzyme system in metabolism and is responsible for the metabolism of drugs, carcinogens, steroid hormones, and environmental pollutants. CYP genes are markedly responsive to the stimulatory and inhibitory effects of xenobiotics and provide a powerful tool to investigate gene-environment interaction. The major objective of the present study was to investigate the ability of carbendazim to modulate CYP-dependent monooxygenases and antioxidant enzymes in rat liver, kidney, lung, and testis. Treatment of male rats with 10, 50, and 100 mg/kg carbendazim intraperitoneally once daily for 4 days decreased testis spermatid density dose-dependently. In liver microsomes, the carbendazim treatment increased P450 content, NADPH-cytochrome c reductase, 7-ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), pentoxyrsorufin O-dealkylase, and 7-ethoxycoumarin O-deethylase (ECOD) activities. In kidney microsomes, carbendazim increased P450 content and EROD and ECOD activities. In lung microsomes, the treated increased EROD activity. In testis microsomes, the treatment increased NADPH-cytochrome c reductase activity. Carbendazim increased glutathione S-transferase (GST) and catalase activities in liver cytosol and GST and superoxide dismutase activities in testis cytosol. The fungicide decreased glutathione content in the kidneys and lipid peroxidation in the testes. Oral administration of 400 mg/kg carbendazim for 7 days increased MROD activity in liver microsomes. The results of immunoblot and RT-PCR analyses showed that carbendazim induced CYP1A1/2 and CYP2B proteins and mRNA in the liver and CYP1A1 protein and mRNA in kidneys and lungs. These present findings show that carbendazim is an inducer of CYP1A1/2 and CYP2B in rats. The significance of carbendazim induction of CYP in metabolic activation warrants further investigations.目錄 中文摘要----------------------------------------------------------------------------------------------1 英文摘要----------------------------------------------------------------------------------------------2 第一章、研究背景 第一節、農藥使用量現況--------------------------------------------------------------------------3 第二節、Benzimidazole類的農藥----------------------------------------------------------------3 第三節、生物體內代謝酵素-----------------------------------------------------------------------5 第四節、貝芬替對細胞色素P450影響---------------------------------------------------------6 第二章、研究方法與步驟 第一節、實驗材料 i. 實驗動物----------------------------------------------------------------------------------9 ii. 藥品----------------------------------------------------------------------------------------9 iii. 劑量效應關係實驗----------------------------------------------------------------------9 第二節、實驗方法 i. 細胞微粒體及細胞液的製備----------------------------------------------------------9 ii. 微粒體蛋白含量測定------------------------------------------------------------------10 iii. 細胞液蛋白質含量測定---------------------------------------------------------------10 iv. 組織均質液蛋白質含量測定---------------------------------------------------------10 v. P450含量測定--------------------------------------------------------------------------11 vi. Cytochrome b5含量的測定-----------------------------------------------------------11 vii. NADPH-cytochrome P450 reductase活性測試------------------------------------11 viii. 7-Ethoxyresorufin O-deethylase Activity Assay------------------------------------12 ix. Methoxyresorufin O-demethylase Activity Assay----------------------------------12 x. Pentoxyresorufin O-dealkylase Activity Assay-------------------------------------13 xi. 7-Ethoxycoumarin O-deethylase Activity Assay-----------------------------------13 xii. Aniline Hydroxylase Activity Assay-------------------------------------------------14 xiii. Erythromycin N-demethylase Activity Assay---------------------------------------14 xiv. Glutathione S-Transferase Activity Assay-------------------------------------------15 xv. Superoxide Dismutase Activity Assay-----------------------------------------------15 xvi. Catalase Activity Assay----------------------------------------------------------------15 xvii. Lipid Peroxidation Assay--------------------------------------------------------------16 xviii. Total Glutathione Determination-----------------------------------------------------16 xix. Glutathione Disulfided Determination-----------------------------------------------17 xx. Sperm Density---------------------------------------------------------------------------17 xxi. 組織RNA萃取-------------------------------------------------------------------------17 xxii. 反轉錄聚合鏈反應---------------------------------------------------------------------18 xxiii. 聚合酶連鎖反應以及引子序列及反應條件---------------------------------------18 xxiv. 聚丙烯醯胺膠電泳（Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, SDS-PAGE）及Immunoblot分析---------------------------------19 xxv. 統計分析---------------------------------------------------------------------------------20 第三章、結果 第一節、貝芬替對雄大鼠體重影響-------------------------------------------------------------21 第二節、貝芬替對睪丸精子數目影響----------------------------------------------------------21 第三節、貝芬替對肝臟細胞色素P450的影響-----------------------------------------------21 第四節、貝芬替對腎臟、肺臟細胞色素P450影響-----------------------------------------22 第五節、貝芬替對抗氧化酵素的影響----------------------------------------------------------22 第六節、貝芬替對脂質過氧化、total GSH、GSSG的影響-----------------------------------23 第七節、外加貝芬替對肝臟7-ethoxyresorufin O-deethylase、7-ethoxycoumarin O-deethylase的影響--------------------------------------------------------------------23 第八節、大鼠口服貝芬替對肝臟微粒體的影響----------------------------------------------23 第九節、貝芬替對細胞色素P450蛋白量的影響--------------------------------------------23 第十節、貝芬替對細胞色素P450 mRNA的影響--------------------------------------------24 第四章、討論---------------------------------------------------------------------------------------25 參考文獻---------------------------------------------------------------------------------------------29 表目錄 表1. 處理貝芬替對雄性大鼠器官重量之影響----------------------------------------------35 表2. 處理貝芬替對雄性大鼠器官相對重量之影響----------------------------------------36 表3. 處理貝芬替對大鼠肝臟微粒體細胞色素P450單氧酶之影響--------------------37 表4. 處理貝芬替對大鼠腎臟、肺臟和睪丸微粒體細胞色素P450單氧酶之影響--38 表5. 處理貝芬替對大鼠肝和腎細胞液中抗氧化酵素之影響----------------------------39 表6. 處理貝芬替對大鼠肺臟和睪丸細胞液中抗氧化酵素之影響----------------------40 表7. 處理貝芬替對大鼠肝臟、腎臟和睪丸脂質過氧化、glutathione含量之影響--41 表8. 外加不同濃度的貝芬替對大鼠微粒體中7-ethoxyresorufin O-deethylase和7-ethoxycoumarin O-deethylase活性之影響------------------------------------------42 表9. 大鼠口服貝芬替對肝臟微粒體中細胞色素P450單氧酶之影響-----------------43 表10. 細胞色素P450 RT-PCR分析之引子序列和溫度條件-----------------------------44 表11. 使用西方點墨法偵測處理貝芬替的大鼠肝臟微粒體中細胞色素P4501A1/2、2B、2E和3A以及腎臟和肺臟微粒體中的細胞色素P450 1A1-----------------45 表12. 使用RT-PCR偵測處理貝芬替的大鼠肝臟中細胞色素P450 mRNA 1A1/2和2B以及腎臟和肺臟中細胞色素P450 1A1-------------------------------------------46 圖目錄 圖1. 貝芬替對雄性大鼠睪丸精子數目之影響----------------------------------------------47 圖2. 使用西方點墨法偵測處理貝芬替的大鼠肝臟微粒體中細胞色素P450 1A1/2、2B、2E、3A--------------------------------------------------------------------------------48 圖3. 使用西方點墨法偵測處理貝芬替的大鼠腎臟和肺臟微粒體中的細胞色素P450 1A1------------------------------------------------------------------------------------------50 圖4. 使用RT-PCR偵測處理貝芬替的大鼠肝臟中細胞色素P450 mRNA 1A1/2和2B--------------------------------------------------------------------------------------------51 圖5. 使用RT-PCR偵測處理貝芬替的大鼠腎肺中細胞色素P450 mRNA 1A1-------5