Stress proteins and tolerance to focal cerebral ischemia
Stress proteins and tolerance to focal cerebral ischemia
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DOI：
10.1097/00004647-199607000-00006
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发表时间：
1996-07-01
影响因子：
6.3
通讯作者：
Simon, RP
中科院分区：
文献类型：
--
作者：
Chen, J;Graham, SH;Simon, RP
应激蛋白在多种神经元损伤后被诱导。可诱导的72-kDa热休克蛋白（hsp 70）是一种应激蛋白，在体外可保护神经元免受谷氨酸毒性。Hsp 70也被认为是缺血耐受现象的基础，由此短暂的亚致死间隔的全脑缺血保护海马免受随后的致死性长时间缺血。为探讨局灶性脑缺血后皮质是否出现耐受现象，用线栓法阻断大鼠大脑中动脉，（3 × 10-isc）被45分钟的再灌注期分开构成了所研究的预处理缺血的最有效范例，并在随后的100分钟MCA闭塞后72小时显著减少梗死体积。如果3 × 10-isc和100分钟缺血之间的间隔为2、3或5天，而不是1或7天，则该方法诱导保护。三个10分钟的短暂缺血单独产生最小的组织学变化在72小时的皮质。此外，在MCA闭塞之前或期间，在3 × 10-isc后72 h，耐受区域的局部脑血流没有显著变化。为了探讨应激蛋白在耐受诱导中的作用，研究了hsp 70和葡萄糖调节蛋白grp 75和grp 78的表达。在3 × 10-isc后1、2、3、5、7和14天，通过Western印迹分析评价来自已经历预处理缺血的脑耐受区域的样品。热休克蛋白70表达的时间进程与耐受性最密切相关。Hsp 70蛋白表达在耐受性存在期间（2-5天）增加，但此后（7和14天）不增加。然而，热休克蛋白70也增加之前，耐受性存在（在1天）。免疫细胞化学结果显示，3 × 10-isc后24 h，hsp 70蛋白在耐受区的神经元中表达，72 h后，hsp 70蛋白在神经元和胶质细胞中均有表达。尽管免疫细胞化学表明grp 75和grp 78的神经元表达增加，但通过Western印迹法测定的蛋白质表达在耐受之前（在1天）、期间（在2-5天）和之后（在7天及之后）没有发现显著差异。因此，grp 75和grp 78表达的时间过程与耐受性无关。这种缺血耐受模型是一种有用的方法，通过它可以探索内源性神经保护机制。
Stress proteins are induced after a variety of neuronal injuries. The inducible 72-kDa heat shock protein (hsp70) is a stress protein that protects neurons from glutamate toxicity in vitro. Hsp70 has also been proposed to underlie the phenomenon of ischemic tolerance whereby brief sublethal intervals of global ischemia protect the hippocampus from subsequent lethal prolonged ischemia. To determine if the phenomenon of tolerance occurs in cortex after focal ischemia, the rat middle cerebral artery (MCA) was occluded by the suture method, Three 10-min intervals of transient ischemia (3 x 10-isc) separated by 45-min periods of reperfusion made up the most effective paradigm of preconditioning ischemia studied, and substantially reduced the volume of infarction 72 h after subsequent 100-min MCA occlusion. This approach induced protection if the interval between the 3 x 10-isc and the 100-min ischemia was 2, 3, or 5 days but not 1 or 7 days. Three 10-min intervals of transient ischemia alone produced minimal histological changes in the cortex at 72 h. Moreover, there were no significant changes in regional cerebral blood flow in the tolerant regions at 72 h after 3 x 10-isc before or during MCA occlusion, To explore the role of stress proteins in the induction of tolerance, expression of hsp70 and the glucose-regulated proteins grp75 and grp78 were studied. Samples from tolerant regions of the brain that had undergone preconditioning ischemia were evaluated at 1, 2, 3, 5, 7, and 14 days after 3 x 10-isc by Western blot analysis. The time course of hsp70 expression most closely correlated with tolerance. Hsp70 protein expression increased during times when tolerance was present (at 2-5 days) but did not increase thereafter (at 7 and 14 days). However, hsp70 was also increased before tolerance was present (at 1 day). Immunocytochemistry showed that hsp70 protein was expressed in neurons in the tolerant regions 24 h after 3 x 10-isc and was expressed in both neurons and glia after 72 h. Although immunocytochemistry suggested that there was increased neuronal expression of grp75 and grp78, no significant differences were found in protein expression as determined by Western blot before (at 1 day), during (at 2-5 days), and after (at 7 days and thereafter) tolerance. Thus, the time course of grp75 and grp78 expression did not correlate with that of tolerance. This model of ischemic tolerance is a useful method by which mechanisms of endogenous neuroprotection may be explored.