2-氯乙醇及其代謝產物2-氯乙酸神經毒性機制之研究

Part I 2-chloroethanol (2-CE) is applied to hasten grapevines sprouting in Taiwan. Decrease of conscious level, hypoglycemia and deterioration of liver and renal function are noted during intoxication. However, the pathophysiological mechanism of this toxicity are not fully understood. Here, we reported a case of 2-CE intoxication which was the complicated with diffuse subcortical hemorrhage, hypoglycemia, and delay types of liver and kidney damages. Patient recovered by treated with fomepizole (4-methylpyrazole, an alcohol dehydrogenase inhibitor, loading dose of 15 mg / kg and maintain dose of 10 mg / kg every 12 hours for 8 days) and N-acetylcysteine (antioxidant, 150 mg / kg every 12hours for 14 days). However, he displayed with decline in the ability of memory, calculation, comprehension and language. These neurologic sequelae might be due to diffuse subcortical hemorrhage. part II 2-chloroethanol (2-CE) is a common and widespread in the industrial use of solvents and chemical raw materials. In Taiwan, farmers apply 2-CE on grape-vines to accelerate grape growth. It is very toxic and could induce multiple organ failure; but until now, the toxicological effects of 2-CE is still remain unclear. Alcohol-dehydrogenase, aldehyde-dehydrogenase and glutathione were hypothesized to be important in the metabolism of 2-CE. The metabolism of 2-CE, 2-chloroacetaldehyde(2-CAA) and 2-chloroacetic acid(2-CA) are the main causes of toxicity. Here, we found that 2-CA significantly decreased Neuro-2a cells viability, and increased reactive oxygen species(ROS), MDA formation and lipid peroxidation production. 2-CA also induced the increases in sub-G1 hypodiploids, annexin V-Cy3 binding, and caspase-3 and -7 activity in Neuro-2a cells, indicating that 2-CA could induce cell apoptosis. Moreover, 2-CA also caused JNK and p38-MAPK activation, mitochondria dysfunction (loss mitochondria membrane potential and cytochrome c release), up-regulation of p53 and down regulation of Bcl-2 and Mdm-2 mRNA expression, PARP and caspase cascades activations, which displayed features of mitochondria-dependent apoptotic signals. These responses could be effectively reversed by antioxidant N-acetylcysteine (NAC), and specific p38-MAPK inhibitor SB203580, but not that JNK inhibitor, could suppress 2-CA-induced apoptosis. In addition, exposure of Neuro-2a cells to 2-CA could trigger ER stress as indicated by the enhancement in ER stress-related molecules induction (such as GRP78, GRP94, CHOP, and XBP1), procaspase-12 cleavage, and calpain activation. NAC effectively inhibited 2-CA-induced ER stress-related markers expression, and transfecting cells with siRNA-GRP78 and siRNA-GRP94 also prevented 2-chloroacetic acid (2-CA) induced apoptosis. Taken together, these results demonstrated for the first that 2-CA-induced oxidative stress causes neuronal cells apoptosis via the mitochondria-dependent and ER stress-triggered apoptosis signaling pathways.