Devi Sachin S, Mehendale Harihara M
Department of Toxicology, College of Pharmacy, The University of Louisiana at Monroe, 700 University Ave, Sugar Hall # 306, Monroe, LA 71209-0470, USA.
Toxicol Appl Pharmacol. 2006 Apr 1;212(1):69-78. doi: 10.1016/j.taap.2005.09.004. Epub 2005 Nov 17.
It is well known that diabetes imparts high sensitivity to numerous hepatotoxicants. Previously, we have shown that a normally non-lethal dose of thioacetamide (TA, 300 mg/kg) causes 90% mortality in type 1 diabetic (DB) rats due to inhibited tissue repair allowing progression of liver injury. On the other hand, DB rats exposed to 30 mg TA/kg exhibit delayed tissue repair and delayed recovery from injury. The objective of this study was to investigate the mechanism of impaired tissue repair and progression of liver injury in TA-treated DB rats by using cDNA microarray. Gene expression pattern was examined at 0, 6, and 12 h after TA challenge, and selected mechanistic leads from microarray experiments were confirmed by real-time RT-PCR and further investigated at protein level over the time course of 0 to 36 h after TA treatment. Diabetic condition itself increased gene expression of proteases and decreased gene expression of protease inhibitors. Administration of 300 mg TA/kg to DB rats further elevated gene expression of proteases and suppressed gene expression of protease inhibitors, explaining progression of liver injury in DB rats after TA treatment. Inhibited expression of genes involved in cell division cycle (cyclin D1, IGFBP-1, ras, E2F) was observed after exposure of DB rats to 300 mg TA/kg, explaining inhibited tissue repair in these rats. On the other hand, DB rats receiving 30 mg TA/kg exhibit delayed expression of genes involved in cell division cycle, explaining delayed tissue repair in these rats. In conclusion, impaired cyclin D1 signaling along with increased proteases and decreased protease inhibitors may explain impaired tissue repair that leads to progression of liver injury initiated by TA in DB rats.
众所周知，糖尿病会使机体对多种肝毒性物质高度敏感。此前，我们已经表明，正常情况下非致死剂量的硫代乙酰胺（TA，300 mg/kg）会导致1型糖尿病（DB）大鼠90%的死亡率，这是由于组织修复受到抑制，使得肝损伤不断进展。另一方面，暴露于30 mg TA/kg的DB大鼠表现出组织修复延迟和损伤后恢复延迟。本研究的目的是通过使用cDNA微阵列来研究TA处理的DB大鼠组织修复受损和肝损伤进展的机制。在TA攻击后0、6和12小时检查基因表达模式，并通过实时RT-PCR对微阵列实验中选定的机制线索进行确认，并在TA处理后0至36小时的时间进程中进一步在蛋白质水平进行研究。糖尿病状态本身会增加蛋白酶的基因表达并降低蛋白酶抑制剂的基因表达。给DB大鼠施用300 mg TA/kg会进一步提高蛋白酶的基因表达并抑制蛋白酶抑制剂的基因表达，这解释了TA处理后DB大鼠肝损伤的进展。在DB大鼠暴露于300 mg TA/kg后，观察到参与细胞分裂周期的基因（细胞周期蛋白D1、胰岛素样生长因子结合蛋白-1、ras、E2F）表达受到抑制，这解释了这些大鼠组织修复受到抑制的原因。另一方面，接受30 mg TA/kg的DB大鼠表现出参与细胞分裂周期的基因表达延迟，这解释了这些大鼠组织修复延迟的原因。总之，细胞周期蛋白D1信号受损，以及蛋白酶增加和蛋白酶抑制剂减少，可能解释了导致TA引发的DB大鼠肝损伤进展的组织修复受损情况。
