Clemens J A, Stephenson D T, Yin T, Smalstig E B, Panetta J A, Little S P
Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Ind 46285-0814, USA.
Stroke. 1998 Mar;29(3):677-82. doi: 10.1161/01.str.29.3.677.
Nuclear factor-kappaB (NF-kappaB) is an oxidative stress responsive transcription factor that is transiently activated in most forebrain neurons in response to transient global ischemia. However, in hippocampal CA1 neurons destined to die, NF-kappaB remains persistently activated. The present study was performed to determine whether an antioxidant (LY231617) that afforded neuroprotection in previous studies had any effect on NF-kappaB activation in hippocampal CA1 neurons after global ischemia.
Rats were subjected to 30 minutes of forebrain ischemia by 4-vessel occlusion (4-VO) and killed at 24 and 72 hours after ischemia. LY231617 was administered orally at a dose of 50 mg/kg 30 minutes before 4-VO and again 4 hours after 4-VO. Neuronal damage was evaluated in sections stained with cresyl violet. Other sections were immunostained with antibodies to NF-kappaB p50 to assess nuclear localization. An electrophoretic mobility shift assay was performed on nuclear extracts from sham- and LY231617-treated rats at 24 and 72 hours after ischemia.
The administration of LY231617 had a significant protective effect on hippocampal CA1 neurons at 72 hours after ischemia (control group, 16 +/- 7 neurons/mm; treated group, 294 +/- 35 neurons/mm, P<.02) and prevented nuclear translocation of activated NF-kappaB as normally seen at 72 hours after ischemia in untreated controls. In contrast, the untreated controls showed activated NF-kappaB at 72 hours after ischemia. At 24 hours after ischemia, both the control group and the LY231617 group showed intense nuclear localization of NF-kappaB.
Activation of NF-kappaB in vitro has been reported to promote proapoptotic as well as antiapoptotic mechanisms, depending on the cell type being investigated. In the present in vivo study, the role of the transient activation of NF-kappaB observed at 24 hours may be responsible for the induction of protective factors in neurons that survive the ischemic insult, whereas the persistent activation of NF-kappaB in hippocampal neurons could be responsible for the induction of proteins that result in CA1 neuronal death.
核因子-κB（NF-κB）是一种氧化应激反应性转录因子，在短暂性全脑缺血后，大多数前脑神经元中会短暂激活。然而，在注定死亡的海马CA1神经元中，NF-κB会持续激活。本研究旨在确定在先前研究中具有神经保护作用的抗氧化剂（LY231617）对全脑缺血后海马CA1神经元中NF-κB激活是否有任何影响。
通过四血管闭塞（4-VO）使大鼠经历30分钟的前脑缺血，并在缺血后24小时和72小时处死。在4-VO前30分钟及4-VO后4小时，以50mg/kg的剂量口服LY231617。用甲酚紫染色的切片评估神经元损伤。其他切片用抗NF-κB p50抗体进行免疫染色以评估核定位。在缺血后24小时和72小时，对假手术组和LY231617处理组大鼠的核提取物进行电泳迁移率变动分析。
LY231617给药在缺血后72小时对海马CA1神经元有显著的保护作用（对照组，16±7个神经元/mm；处理组，294±35个神经元/mm，P<0.02），并阻止了活化的NF-κB的核转位，而在未处理的对照组中，缺血后72小时通常会出现这种核转位。相反，未处理的对照组在缺血后72小时显示NF-κB活化。在缺血后24小时，对照组和LY231617组均显示NF-κB的强烈核定位。
据报道，体外NF-κB的激活根据所研究的细胞类型促进促凋亡以及抗凋亡机制。在本体内研究中，24小时观察到的NF-κB短暂激活可能负责诱导在缺血性损伤中存活的神经元中的保护因子，而海马神经元中NF-κB的持续激活可能负责诱导导致CA1神经元死亡的蛋白质。
