Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA; Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA.
Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA; Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA.
Free Radic Biol Med. 2017 Dec;113:203-211. doi: 10.1016/j.freeradbiomed.2017.09.024. Epub 2017 Sep 28.
Cerebral ischemia-reperfusion (I/R) injury initiates a cascade of events, generating nitric oxide (NO) and superoxide(O) to form peroxynitrite (ONOO), a potent oxidant. Arctic ground squirrels (AGS; Urocitellus parryii) show high tolerance to I/R injury. However, the underlying mechanism remains elusive. We hypothesize that tolerance to I/R modeled in an acute hippocampal slice preparation in AGS is modulated by reduced oxidative and nitrative stress. Hippocampal slices (400µm) from rat and AGS were subjected to oxygen glucose deprivation (OGD) using a novel microperfusion technique. Slices were exposed to NO, O donors with and without OGD; pretreatment with inhibitors of NO, O and ONOO followed by OGD. Perfusates collected every 15min were analyzed for LDH release, a marker of cell death. 3-nitrotyrosine (3NT) and 4-hydroxynonenal (4HNE) were measured to assess oxidative and nitrative stress. Results show that NO/O alone is not sufficient to cause ischemic-like cell death, but with OGD enhances cell death more in rat than in AGS. A NOS inhibitor, SOD mimetic and ONOO inhibitor attenuates OGD injury in rat but has no effect in AGS. Rats also show a higher level of 3NT and 4HNE with OGD than AGS suggesting the greater level of injury in rat is via formation of ONOO.
脑缺血再灌注（I/R）损伤引发一系列事件，生成一氧化氮（NO）和超氧化物（O）形成过氧亚硝酸盐（ONOO），一种强氧化剂。北极地松鼠（AGS；Urocitellus parryii）对 I/R 损伤表现出高耐受性。然而，其潜在机制仍不清楚。我们假设在 AGS 急性海马切片制备中模拟的 I/R 耐受性是通过减少氧化和硝化应激来调节的。使用新的微灌注技术从大鼠和 AGS 中分离出 400µm 的海马切片。将切片暴露于 NO、O 供体和 OGD；用 NO、O 和 ONOO 的抑制剂预处理，然后进行 OGD。每隔 15 分钟收集一次灌流液，分析 LDH 释放，这是细胞死亡的标志物。测量 3-硝基酪氨酸（3NT）和 4-羟基壬烯醛（4HNE）以评估氧化和硝化应激。结果表明，NO/O 本身不足以引起类似缺血的细胞死亡，但与 OGD 一起在大鼠中比在 AGS 中更能增强细胞死亡。NOS 抑制剂、SOD 模拟物和 ONOO 抑制剂可减轻大鼠的 OGD 损伤，但对 AGS 没有影响。大鼠的 3NT 和 4HNE 水平也高于 AGS，表明大鼠的损伤程度更大是通过形成 ONOO 引起的。
