Mahadik S P, Bharucha V A, Stadlin A, Ortiz A, Karpiak S E
Division of Neuroscience, New York State Psychiatric Institute, New York.
J Neurosci Res. 1992 Jun;32(2):209-20. doi: 10.1002/jnr.490320210.
Alterations in cellular membrane structure and the subsequent failure of its function after CNS ischemia were monitored by analyzing changes in the plasma membrane marker enzyme (Na(+) + K(+)-ATPase. The levels of two isozymes of (Na(+) + K(+)-ATPase, alpha+ and alpha, which have distinct cellular and anatomical distributions, were studied to determine if differential cellular damage occurs in primary and peri-ischemic injury areas. The efficacy of monosialoganglioside (GM1) treatment was assessed, since this glycosphingolipid has been shown to reduce ischemic injury by protecting cell membrane structure/function. Using a rat model of cortical focal ischemia, levels of both ATPase isozyme activities were assayed in total membrane fractions from primary ischemic tissue (parietal cortex) and three peri-ischemic tissue areas (frontal, occipital, and temporal cortex) at 1, 3, 5, 7, and 14 days after ischemia. No significant loss of either isozyme's activity occurred in any tissue area at 1 day after ischemia. At 5 days, in the primary ischemic area, both isozyme activity levels decreased by 70-75%. The alpha+ enzyme activity loss persisted up to 14 days, while a 17% recovery in alpha activity occurred. In the three peri-ischemic tissue areas, enzyme activity losses ranged from 42%-59% at 3 days after ischemia. A complete restoration of both isozyme activities was seen at 14 days. After three days of GM1 ganglioside treatment there was no loss of total (Na*+) + K(+)-ATPase activity in the three peri-ischemic areas, and a significantly reduced loss in the primary infarct tissue. An autoradiographic analysis of brain coronal sections using 3H-ouabain supports the enzymatic data and GM1 effects. Reductions in 3H-ouabain binding in all cortical layers at 3 days after ischemia were visualized. GM1 treatment significantly reduced these 3H-ouabain binding losses. In summary, time-dependent quantitative changes in activity levels of ATPase isozymes (alpha+ and alpha) reflect the different degree of membrane damage that occurs in primary vs. peri-ischemic tissues (e.g., irreversible vs. reversible membrane damage), and that ischemia affects cell membranes of all neural elements in a largely similar fashion. GM1 ganglioside was found to reduce plasma membrane damage in all CNS cell types.
通过分析质膜标记酶（Na⁺+K⁺-ATP酶）的变化，监测中枢神经系统缺血后细胞膜结构的改变及其随后的功能衰竭。研究了具有不同细胞和解剖分布的两种（Na⁺+K⁺-ATP酶）同工酶α⁺和α的水平，以确定在原发性和缺血周围损伤区域是否发生不同程度的细胞损伤。评估了单唾液酸神经节苷脂（GM1）治疗的效果，因为这种糖鞘脂已被证明可通过保护细胞膜结构/功能来减少缺血性损伤。使用大鼠皮质局灶性缺血模型，在缺血后1、3、5、7和14天，测定原发性缺血组织（顶叶皮质）和三个缺血周围组织区域（额叶、枕叶和颞叶皮质）总膜组分中两种ATP酶同工酶活性水平。缺血后1天，任何组织区域中两种同工酶的活性均未发生显著损失。在5天时，原发性缺血区域中两种同工酶活性水平均下降了70%-75%。α⁺酶活性损失持续至14天，而α活性恢复了17%。在三个缺血周围组织区域，缺血后3天酶活性损失范围为42%-59%。在14天时观察到两种同工酶活性完全恢复。GM1神经节苷脂治疗3天后，三个缺血周围区域中总（Na⁺+K⁺-ATP酶）活性没有损失，原发性梗死组织中的损失显著减少。使用³H-哇巴因对脑冠状切片进行放射自显影分析支持了酶学数据和GM1的作用。观察到缺血后3天所有皮质层中³H-哇巴因结合减少。GM1治疗显著减少了这些³H-哇巴因结合损失。总之，ATP酶同工酶（α⁺和α）活性水平的时间依赖性定量变化反映了原发性与缺血周围组织中发生的不同程度的膜损伤（例如，不可逆与可逆膜损伤），并且缺血以大致相似的方式影响所有神经元件的细胞膜。发现GM1神经节苷脂可减少所有中枢神经系统细胞类型中的质膜损伤。
