EVALUATION OF TC 99M MAG3 BIOCYTIN AS HEPATOBILIARY AGENT

TC 99M MAG3 生物细胞素作为肝胆药物的评价

• 批准号: 6161480
• 负责人: JORGE A. CARRASQUILLO
• 金额: --
• 依托单位: CLINICAL CENTER
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6161480
• 关键词: 6 thiopurine; autoradiography; chemoprevention; cytochrome P450; drug screening /evaluation; enzyme inhibitors; hepatitis; hepatotoxin; laboratory mouse; liver disorder chemotherapy; liver disorder diagnosis; liver metabolism; liver pharmacology; nonhuman therapy evaluation; radiopharmacology; technetium

Summary of Work: In the course of developing a Tc-99m radiopharmaceutical that incorporates an avidinbiotin system to detect tumors, we have synthesized Tc-99m mercaptoacetyltriglycine-lysine- biotin (Tc-99m MAG3-biocytin). This radiopharmaceutical was shown to be a promising hepatobiliary agent because its hepatic uptake was not affected by elevated levels of bilirubin. In contrast, Tc-99m disofenin, a biliary agent of choice in clinic, shows a decreased hepatic uptake in the presence of high levels of bilirubin, thereby making it difficult to detect hepatic disease caused by hepatocyte dysfunction. During FY 97, we have tested the utility of this new hepatobiliary agent to investigate the potential benefits of synthetic inhibitors of ethanol- inducible cytochrome P450 2E1 (CYP2E1) in an acute hepatitis model caused by a single oral administration of carbon tetrachloride (CC14) in Balb/c mice. it was previously reported that CYP2E1 is responsible for the metabolism of alcohol, fatty acids, acetaminophen and CC14, and that synthetic inhibitors such as isopropyl-2-(1,3-dithioetane-2- ylidene)-2-[N-(4-methylthiazol-2-yl)-carbamoyl] acetate (YH439) and chlormethiazole suppress CYP2E1 gene transcription. For the studies on acute hepatitis mice, the animals were treated with one dose of CC14 (0.25 ml/kg) 18 h before hepatobiliary scintigraphy. For the studies on the protective effects of YH439, mice were pretreated with two doses of YH439 (50 mg/kg/day) at 48 h and 24 h and one dose of CC14 at 18 h before the scintigraphy. The whole-body scintigraphic data were acquired over a course of 30 min. Time-activity curves were generated by drawing circular regions of interest over the upper left lobe of the liver, and also the head and neck area for the blood background. The physical parameters, such as peak liver/heart ratio (Rmax), peak hepatic uptake time (Tmax), and hepatic half-clearance time (HCT) were then determined from time-activity curves. In normal mice, Tc-99m MAG3-biocytin was taken up rapidly by liver and then excreted via biliary system (Rmax 8.3, Tmax 128 s, HCT 397 s). In mice with CC14-induced hepatotoxicity, dynamic images showed impaired hepatic uptake with prolonged blood background radioactivity (Rmax 1.5, Tmax 74 s, HCT 747 s). This altered scintigraphic result was consistent with typical centrilobular necrosis in histopathology. In contrast, treatment of YH439 not only prevented the centrilobular necrosis but also significantly improved the kinetic parameters (Rmax 6.2, Tmax 97 s, HCT 377 s). This study demonstrated that the hepatotoxicity was induced by CYP2E1-mediated reaction and its protection by CYP2E1 inhibitor could be studied in vivo using external scintigraphic imaging methods.

工作总结：在研制~(99m)Tc的过程中 放射性药物，结合了一个亲和素系统来检测 肿瘤，我们合成了~(99)m-巯基乙酰甘氨酸-赖氨酸- 生物素(~(99)m-MAG3-生物细胞素)。这种放射性药物被证明是 一种很有前途的肝胆剂，因为它的肝脏摄取不是 受胆红素水平升高的影响。相比之下，~(99m)Tc-异氰菊酯， 临床上选择的一种胆汁制剂，显示肝脏摄取减少 在胆红素水平较高的情况下，因此很难 检测由肝细胞功能障碍引起的肝病。在财年期间 97，我们已经测试了这种新的肝胆剂对 研究乙醇合成抑制剂的潜在好处- 急性肝炎模型中诱导型细胞色素P450 2E1的表达 由单次口服四氯化碳(CC14)引起 在Balb/c小鼠体内。此前有报道称，CYP2E1对此负责 对于酒精、脂肪酸、对乙酰氨基酚和CC14的代谢，以及 合成缓蚀剂，如异丙基-2-(1，3-二硫代乙烷-2- Ylidene)-2-[N-(4-methylthiazol-2-yl)-carbamoyl]乙酸酯(YH439)和 氯甲唑抑制细胞色素P4502基因转录。为了研究关于 急性肝炎小鼠，给小鼠一次性注射CC14。 肝胆核素扫描前18h注射0.25ml/kg。为了研究关于 YH439对小鼠的保护作用 YH439(50 mg/kg/d)，48小时和24小时，一次CC14，18小时 在闪光照相之前。采集全身核素扫描数据 超过30分钟的疗程。通过绘制时间-活动曲线 肝脏左上叶上的圆形感兴趣区，以及 还有头部和颈部的血迹背景。体能 参数，如最大肝脏/心脏比率(Rmax)、最大肝脏摄取量 然后测定时间(Tmax)和肝脏半清除时间(Hct 从时间-活动曲线。在正常小鼠中，~(99m)Tc-MAG3-生物细胞素 迅速被肝脏吸收，然后通过胆道系统排泄(Rmax 8.3，Tmax 128 S，Hct 397 S)。在CC14诱导的肝毒性小鼠中， 动态图像显示肝脏摄取受损，并伴有长时间的血液 背景放射性(Rmax 1.5，Tmax 74 S，Hct747 S)。这一点改变了 核素扫描结果与典型的小叶中心坏死一致 在组织病理学方面。相比之下，YH439的治疗不仅可以预防 小叶中心性坏死也明显改善了动力学 参数(Rmax 6.2，Tmax 97 S，Hct377 S)。这项研究证明 细胞色素P450_2E_1介导的肝毒性及其临床意义 细胞色素P450-2E1抑制剂的保护作用可在体内进行研究 闪光照相成像方法。