| Summary: | 碩士 === 國立陽明大學 === 藥理學研究所 === 96 === Glucose and oxygen are essential nutrients for the brain’s neurons to survive and function normally. During stroke, deficiency of glucose and oxygen induces sub- cellular damage (e.g., mitochondria) and production of large amounts of free radicals, finally leading to neuronal death that is a crucial deleterious consequence of ischemia. So far, there is no effective and safe drug available for stroke treatment in the clinic. Therefore, it’s very important to find out novel drug(s) for the treatment of ischemic stroke. In this study, an in vitro experimental ischemia-induced neuronal damage was performed by glucose and oxygen deprivation (OGD) in cultured human dopaminergic-like neuroblastoma cell line (SH-SY5Y) to screen potent protective drugs and to determine the underlying mechanism(s), as well as the efficacy in stroke animal model. Among 12 drugs screened, trolox, a vitamin E analogue, displayed the most potent neuronal protective property. The OGD induced around 70% of cell death and significant amount of apoptosis as revealed by the upregulation of cleavage poly (ADP-ribose) polymerase (PARP) and annexin V staining. Using DCFH2-DA and JC-1 as markers for the measurement of intracellular reactive oxygen species (ROS) production and the changes of mitochondria membrane potential, respectively, in the presence of NADPH oxidase (NOX) inhibitors (DPI and apocynin) or p38 activity inhibitor (SB203580), I found OGD triggered a large amount of intracellular ROS production, possibly through impairment of mitochondria function and activation of NOX, through activation of p38 signaling. Trolox (250 to 500 �嵱) concentration dependently rescued cell from OGD induced damage by suppression of ROS production and preservation of the mitochondria potential, as well as reducing the activation of p38 signaling. Finally, administration of trolox (0.125 mg/kg, i.v.) to a stroke related animal model by middle cerebral artery occlusion (MCAO) showed that trolox significantly improved the neurological deficit score from 4.5 (MCAO group) to 7.2 (MCAO + trolox group) and reduced cerebral infarct volume from 14% (MCAO group) to 8% (MCAO + trolox group). Based on these results, I conclude that the in vitro OGD model is a successful cellular model for the screening of potent drugs for the treatment of stroke in rats; trolox could protect mitochondria against OGD-induced free radical production and cell-death signaling through which to reduce stroke induced brain damage.
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