Liver Transplantation Program and Department of Anesthesiology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, 123 Ta-Pei Rd., Niao-Sung, Kaohsiung 83305, Taiwan.
Phytomedicine. 2010 May;17(6):469-74. doi: 10.1016/j.phymed.2009.07.012. Epub 2009 Aug 15.
Although magnolol is cytoprotective against warm ischemia/reperfusion injury, its effect on cold preservation has not been fully investigated. This study aimed at examining whether magnolol maintains the liver graft integrity after cold preservation and elucidating the underlying mechanisms in terms of apoptotic signaling under both normothermic and hypothermic conditions. After being preserved in Ringer's lactate (RL) at 4 degrees C for 6h ex vivo, the magnolol-treated grafts demonstrated significantly higher AST, ALT, and LDH levels in perfusates than those from negative controls. TUNEL staining showed no difference in the number of apoptotic nuclei in both groups, whereas a more intense apoptotic signal in magnolol-treated grafts was shown as compared with the controls. In vitro data showed no significant difference in viability of RL-preserved clone-9 hepatocytes between the magnolol-treated and control groups, while magnolol pretreatment at 30min before cold preservation prominently induced hepatocyte cell death. RT-PCR and Western blotting analyses revealed a suppression in Bcl-2, but an up-regulation in Bax expression in clone-9 cells after magnolol treatment. Magnolol suppressed the ratios of NF-kappaB to I-kappaBalpha protein contents and I-kappaBalpha phosphorylation induced by TNF-alpha, and potentiated mitochondrial cytochrome c release and subsequent caspase-3 cleavage. Conversely, caspase-3 inhibitor attenuated magnolol-induced hepatotoxicity. We concluded that magnolol could not protect liver grafts from cold ischemia/reperfusion injury. High concentration of magnolol under serum-reduced conditions attenuates NF-kappaB-mediated signaling and induces intrinsic apoptotic pathway, thereby inducing in vitro hepatotoxicity.
尽管厚朴酚对热缺血/再灌注损伤具有细胞保护作用，但它对冷保存的影响尚未得到充分研究。本研究旨在探讨厚朴酚是否能在常温及低温条件下通过凋亡信号通路来维持冷保存后肝移植物的完整性，并阐明其潜在机制。在 4°C 的林格氏乳酸盐（RL）中离体保存 6 小时后，与阴性对照组相比，厚朴酚处理的供体肝组织在灌流液中的 AST、ALT 和 LDH 水平显著升高。TUNEL 染色显示两组供体肝组织凋亡核的数量无差异，而与对照组相比，厚朴酚处理的供体肝组织中凋亡信号更强。体外数据显示，在 RL 保存的 clone-9 肝细胞中，厚朴酚处理组和对照组之间的细胞活力无显著差异，而在冷保存前 30 分钟用厚朴酚预处理则显著诱导肝细胞死亡。RT-PCR 和 Western blot 分析显示，厚朴酚处理后 clone-9 细胞中的 Bcl-2 表达受到抑制，但 Bax 表达上调。厚朴酚抑制 TNF-α诱导的 NF-kappaB 与 I-kappaBalpha 蛋白含量的比值和 I-kappaBalpha 的磷酸化，并增强线粒体细胞色素 c 释放和随后的 caspase-3 切割。相反，caspase-3 抑制剂可减轻厚朴酚诱导的肝毒性。我们得出结论，厚朴酚不能保护肝移植物免受冷缺血/再灌注损伤。在血清减少的条件下，高浓度的厚朴酚减弱 NF-kappaB 介导的信号通路并诱导内在凋亡途径，从而导致体外肝毒性。
