Bouis P, Brouillard J F, Fischer V, Donatsch P, Boelsterli U A
Department of Toxicology, Sandoz Ltd, Basel, Switzerland.
Biochem Pharmacol. 1990 Jan 15;39(2):257-66. doi: 10.1016/0006-2952(90)90024-f.
This study was designed to examine the relationship between the extent of Sandimmun (cyclosporin A, SIM) metabolism and SIM-induced hepatotoxicity both in vivo and in primary cultures of rat hepatocytes. Firstly, SIM (50 mg/kg p.o.) was administered daily to male Wistar rats for 10 days with or without co-administration of Aroclor 1254. SIM-induced hepatotoxicity appeared after 4 days of treatment and was enhanced after 10 administrations of SIM. Total plasma proteins were decreased and hyperbilirubinemia as well as increased levels of plasma bile salts were prominent. Aroclor 1254 stimulated total hepatic cytochrome P-450 3.7-fold, and markedly increased the rate of SIM metabolism and plasma elimination as determined by both HPLC and RIA techniques. However, this induction did not change the degree of SIM-induced hepatotoxicity. Secondly, short-term cultures of hepatocytes obtained from normal rats and from rats pretreated with either Aroclor 1254 or dexamethasone, a specific inducer of the cytochrome P-450 III gene family responsible for the formation of the primary SIM metabolites M1, M17 and M21, were incubated with various concentrations of SIM for up to 17 hr. At 1 microM SIM, both inducers greatly increased the rate of SIM metabolism in vitro, producing, however, different metabolite patterns. In the hepatocyte cultures, SIM inhibited the incorporation of amino acids into proteins. In addition, a small fraction of [3H]-labeled SIM was covalently bound to hepatocellular macromolecules. Although the fraction of covalently bound SIM was markedly increased in cells from dexamethasone-treated rats, the degree of inhibition of hepatocellular protein synthesis was not changed in cells from induced rats. In contrast to SIM-induced nephrotoxicity, these results suggest that increased rates of SIM biotransformation by inducers of drug metabolism are not associated with an attenuation of hepatotoxicity both in vivo and in vitro.
本研究旨在探讨山地明（环孢素A，SIM）代谢程度与SIM诱导的肝毒性之间的关系，研究在体内和大鼠原代肝细胞培养中进行。首先，对雄性Wistar大鼠每日口服给予SIM（50mg/kg），持续10天，同时或不同时给予多氯联苯混合物1254。治疗4天后出现SIM诱导的肝毒性，在给予10次SIM后毒性增强。血浆总蛋白降低，高胆红素血症以及血浆胆汁盐水平升高显著。多氯联苯混合物1254使肝脏总细胞色素P-450增加3.7倍，并通过高效液相色谱法（HPLC）和放射免疫分析法（RIA）测定显著提高了SIM的代谢率和血浆清除率。然而，这种诱导并未改变SIM诱导的肝毒性程度。其次，将从正常大鼠以及用多氯联苯混合物1254或地塞米松预处理的大鼠获得的肝细胞进行短期培养，地塞米松是细胞色素P-450 III基因家族的特异性诱导剂，负责主要SIM代谢产物M1、M17和M21的形成，将其与不同浓度的SIM孵育长达17小时。在1μM SIM时，两种诱导剂均显著提高了体外SIM的代谢率，但产生了不同的代谢产物模式。在肝细胞培养物中，SIM抑制氨基酸掺入蛋白质。此外，一小部分[3H]标记的SIM与肝细胞大分子共价结合。虽然在地塞米松处理的大鼠细胞中，共价结合的SIM部分显著增加，但诱导大鼠细胞中肝细胞蛋白质合成的抑制程度并未改变。与SIM诱导的肾毒性相反，这些结果表明，药物代谢诱导剂使SIM生物转化速率增加与体内和体外肝毒性的减弱无关。
