Nishino Kazuhiko, Nowak Thaddeus S
Department of Neurology, University of Tennessee, Memphis, 38163, USA.
J Cereb Blood Flow Metab. 2004 Feb;24(2):167-78. doi: 10.1097/01.WCB.0000100853.67976.8B.
The distribution and time course of expression of the heat shock/stress proteins, hsp27 and hsp72, were evaluated in a highly controlled gerbil model of ischemic injury and tolerance induction, in which the duration of ischemic depolarization in each hippocampus provides a precise quantitative index of insult severity. Gerbils were subjected to brief priming insults (2- to 3.5-minute depolarization) that produce optimal preconditioning, to severe test insults (6- to 8.5-minute depolarization) that produce complete CA1 neuron loss in naive animals, or to combined insults administered 1 week apart, after which almost complete tolerance to CA1 neuron injury is observed. Immunoreactivities of hsp27, hsp72, glial fibrillary acidic protein and microtubule-associated protein 2 (MAP2) were evaluated in animals perfused at defined intervals after the final insult in each treatment group, using a variation of established antigen-retrieval procedures that significantly improves detection of many proteins in vibratome brain sections. Hsp72 was detected in CA1 neurons of some hippocampi 2 to 4 days after preconditioning, but this was only seen after the longest priming depolarizations, whereas shorter insults that still induced optimal tolerance failed to induce hsp72. Hsp72 was induced after test insults in preconditioned hippocampi, but at a higher depolarization threshold than observed for naive animals. An astrocytic localization of hsp27 was observed in regions of neuron injury, as indicated by reduced MAP2 immunoreactivity, and was primarily restricted to dentate hilus after preconditioning insults. These results establish that limited hilar lesions are characteristic of optimal preconditioning, whereas prior neuronal expression of either hsp72 or hsp27 is not required for ischemic tolerance.
在一个高度可控的沙鼠缺血性损伤和耐受性诱导模型中，评估了热休克/应激蛋白hsp27和hsp72的表达分布及时间进程，其中每个海马体缺血去极化的持续时间提供了损伤严重程度的精确量化指标。沙鼠接受短暂的预处理性损伤（2至3.5分钟去极化）以产生最佳预处理效果，或接受严重的测试性损伤（6至8.5分钟去极化），后者在未预处理的动物中会导致CA1神经元完全丧失，或接受间隔1周给予的联合损伤，之后观察到对CA1神经元损伤几乎完全的耐受性。在每个治疗组最后一次损伤后的特定时间间隔对动物进行灌注，使用一种改进的既定抗原修复程序来评估hsp27、hsp72、胶质纤维酸性蛋白和微管相关蛋白2（MAP2）的免疫反应性，该程序显著提高了在振动切片脑切片中对许多蛋白质的检测。预处理后2至4天，在一些海马体的CA1神经元中检测到hsp72，但这仅在最长的预处理去极化后出现，而较短的仍能诱导最佳耐受性的损伤未能诱导hsp72。在预处理的海马体中，测试性损伤后诱导了hsp72，但去极化阈值高于未预处理动物。如MAP2免疫反应性降低所示，在神经元损伤区域观察到hsp27的星形细胞定位，且在预处理性损伤后主要局限于齿状回门区。这些结果表明，有限的门区损伤是最佳预处理的特征，而缺血耐受性并不需要hsp72或hsp27的先前神经元表达。
