Neurotoxic effects of exogenous tissue-type plasminogen activator on the normal brain

组织型纤溶酶原激活剂（tPA）静脉和动脉给药的溶栓治疗已被确立用于治疗急性缺血性卒中。tPA也被认为具有神经毒性作用。本研究的目的是通过微透析探针灌注到皮质后检查tPA诱导的神经毒性。成年雄性Wistar大鼠分为3组：（a）tPA高剂量组（30 μmol/l），（B）tPA低剂量组（15μ mol/l），（c）生理盐水对照组。通过苏木精和伊红（HE）染色切片的图像分析，对病变体积进行组织学定量。通过静脉注射Evans蓝评价tPA诱导的血脑屏障（BBB）破坏。使用抗层粘连蛋白抗体通过免疫组织化学评价基底层的损伤。还研究了tPA灌注后一氧化氮（NO）合成的顺序变化。在对照组中，除探针束外，未观察到结构变化。在两个tPA组中，探针周围产生苍白的病变，显微镜下，神经元显示坏死变化。高剂量tPA组的病变体积显著更大。在rtPA灌注动物中观察到明显和广泛的Evans蓝外渗。层粘连蛋白免疫反应性的血管中的tPA诱导的病变丢失。tPA灌流后NO终产物水平明显升高。这些结果提供了tPA的直接神经毒性的证据，并且还表明tPA引起BBB破坏和基底层损伤，从而增加水肿形成。

Thrombolytic therapy with intravenous and intra-arterial administration of tissue-type plasminogen activator (tPA) has been established for the treatment of acute ischemic stroke. tPA has also been suggested to have neurotoxic effects. The purpose of this study was to examine tPA-induced neurotoxicity after perfusion into the cortex via a microdialysis probe. Adult male Wistar rats were divided into three groups : (a)high-dose (30 μmol/l) tPA group ; (b)low-dose (15μ mol/l) tPA ; (c)control (physiological saline) group. The volume of the lesion was quantified histologically by image analysis of hematoxylin and eosin (HE)-stained sections. tPA-induced blood-brain barrier (BBB) disruption was evaluated by intravenous injection of Evans blue. Injury of the basal lamina was evaluated by immunohistochemistry using an anti-laminin antibody. Sequential changes in nitric oxide (NO) synthesis following tPA perfusion was also investigated. In the control group, no structural change was observed except for the probe tract. In both tPA groups, a pale lesion was produced around the probe, and microscopically, neurons showed necrotic changes. The volume of the lesions was significantly higher in the high-dose tPA group. Marked and extensive extravasation of Evans blue was observed in the rtPA-perfused animals. Laminin immunoreactivity of blood vessels in the tPA-induced lesions was lost. The level of NO end-products was increased markedly after tPA perfusion. These results provide evidence of direct neurotoxicity of tPA, and also suggest that tPA causes BBB disruption and injury of the basal lamina, thereby increasing edema formation.