Ito T, Takenaka K, Sakai H, Yoshimura S, Hayashi K, Noda S, Sakai N
Department of Neurosurgery, Gifu University School of Medicine, Japan.
Neurol Res. 2000 Jun;22(4):413-9. doi: 10.1080/01616412.2000.11740693.
Tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) have been used for thrombolitic therapy. In contrast, it is suggested that these compounds might be involved in neuronal cell damage. The activation and the function of tPA and uPA are less understood in ischemic brain tissue. Therefore, changes in tPA and uPA mRNA in rat brain tissue after MCA occlusion and in the neuronal cell line, PC12 cells, during the hypoxic stimulation were examined. Permanent middle cerebral artery (MCA) occlusion was induced by advancing a filament into the internal carotid artery in 36 adult male Sprague-Dawley rats. The ischemic cerebral cortex and contralateral cortex of MCA area, and bilateral hippocampus were collected at 0 (controls), 1, 3, 6, 12 and 24 h after occlusion. Hypoxia was induced in PC12 cells with a multigas incubator (set to 1% O2). The quantitative reverse transcription-polymerase chain reaction acted as a measurement of alteration in mRNA levels. The mRNA levels of tPA and uPA were significantly increased after MCA occlusion in the ischemic cerebral cortex. The magnitude of the increase in tPA and uPA mRNA in 24 h after occlusion was twice the value in sham-operated rat (0 h). The increases of tPA mRNA were time-dependent in insult and contralateral hippocampus. The increase of uPA mRNA was also seen in the hippocampus bilaterally, although the increase was more significant on the ipsilateral side. In PC12 cells, necrotic (approximately 35%) and apoptotic cells (approximately 65%) could be distinguished by hypoxic stimulus for 24 h, and the mRNA for tPA was significantly increased for 6 h-12 h, while the mRNA for uPA was not detected at any point in the study. Our results suggest that focal ischemia might result in the activation of these proteases not only in the insult but also in the contralateral brain tissue.
组织型纤溶酶原激活剂（tPA）和尿激酶型纤溶酶原激活剂（uPA）已用于溶栓治疗。相比之下，有人提出这些化合物可能与神经元细胞损伤有关。在缺血性脑组织中，tPA和uPA的激活及功能尚不清楚。因此，研究了大鼠脑组织在大脑中动脉闭塞后以及神经元细胞系PC12细胞在缺氧刺激期间tPA和uPA mRNA的变化。通过将一根细丝推进成年雄性Sprague-Dawley大鼠的颈内动脉来诱导永久性大脑中动脉（MCA）闭塞。在闭塞后0（对照组）、1、3、6、12和24小时收集缺血性大脑皮质、MCA区域的对侧皮质以及双侧海马。使用多气体培养箱（设置为1%氧气）在PC12细胞中诱导缺氧。定量逆转录聚合酶链反应用于测量mRNA水平的变化。大脑中动脉闭塞后，缺血性大脑皮质中tPA和uPA的mRNA水平显著升高。闭塞后24小时tPA和uPA mRNA的增加幅度是假手术大鼠（0小时）的两倍。tPA mRNA的增加在损伤侧和对侧海马中呈时间依赖性。双侧海马中也可见uPA mRNA的增加，尽管同侧的增加更为显著。在PC12细胞中，缺氧刺激24小时可区分出坏死细胞（约35%）和凋亡细胞（约65%），tPA的mRNA在6至12小时显著增加，而在本研究的任何时间点均未检测到uPA的mRNA。我们的结果表明，局灶性缺血可能不仅在损伤部位而且在对侧脑组织中导致这些蛋白酶的激活。
