Basic investigation of hypothermia for a treatment of stroke : ischemic neuronal damage by the disruption of blood-brain barrier and microglial activation

通过检测静脉注射伊文思蓝染料在前脑缺血沙土鼠中的外渗来评价血脑屏障（BBB）的破坏。通过荧光法估计染料外渗。缺血后1天前脑可见轻度渗出，4天最严重。低温沙鼠全脑渗出减少。在低温条件下前脑缺血后通过侧脑室给予血清时，在海马CA 1区神经元中检测到神经元死亡。与正常大鼠相比，无白蛋白大鼠大脑中动脉闭塞1 h后24 h的梗死体积减少。本实验观察了血清对培养的小胶质细胞产生超氧阴离子（O_2^-）、一氧化氮（NO）和肿瘤坏死因子-α（TNF-α）的影响。我们发现一种血清因子，白蛋白， 关于我们 血清能增加脂多糖（LPS）诱导的NO和TNF-α的产生。我们确定了白蛋白分子内这种增强的活性位点。对一系列合成肽的活性测定表明，活性最低的序列为Leu-His-Thr-Leu。活化的小胶质细胞可释放多种神经毒性介质。已经提出这种神经毒性介质在脑缺血下施加神经元损伤。因此，抑制小胶质细胞的活化将为缺血性脑卒中的治疗打开一个新的窗口。我们研究了短期亚低温联合每日γ-谷氨酰乙酰胺（茶氨酸）治疗对沙土鼠短暂性前脑缺血迟发性神经元死亡的保护作用。缺血后每日给予茶氨酸5 mg/kg，共30天。存活30天后，海马CA 1神经元损伤的程度进行了组织学评估。与对照组（8%存活率）相比，短时间和轻度缺血后低温结合茶氨酸治疗导致存活的CA 1神经元显著增加（分别为67%和72%）。这些发现表明，短时间和轻度低温与茶氨酸组合对缺血性神经元损伤具有一致的有益作用。少

Blood-brain barrier (BBB) breakdown was evaluated by examining extravasation of intravenously injected Evans Blue dye in forebrain ischemic gerbils. Dye extravasation was estimated by the fluorometric method. Slight extravasation was observed in the forebrain 1 days after ischemia, and was most severe 4 days after ischemia. Extravasation decreased in whole of brain in the hypothermic gerbils. When serum were administered through the lateral ventricle after forebrain ischemia under hypothermic conditions, neuronal death was detected in CA1 neurons of the hippocampus. Infarction volume 24 h after 1 h MCA occlusion decreased in none-albumin rats compared with normal rats. These results suggest that infiltration of serum factors into brain parenchyma may play a key role in ischemic neuronal death.We examined the effect of serum on the production of super oxide (O_2^-), nitric oxide (NO) and tumor necrosis factor-α (TNF-α) in rat cultured microglia. We found that a serum factor, albumin, in … More creased phorbol ester (PMA)-induced O_2^- production and that serum also enhanced lipopolysaccharide (LPS)-induced production of NO and TNF-α. We identified the active site of this enhancement within the albumin molecule. The activated of a series of synthesized peptides conclusely indicated that the minimum active sequences was Leu-His-Thr-Leu. Activated microglia can release various neurotoxic mediators. Such neurotoxic mediators have been proposed to exert neuronal damage under brain ischemia. Therefore, suppression of microglial activation will open a new window for treatment of ischemic stroke.We examined the protective effect of short-duration and mild hypothermia in combination with daily γ-glutamylethylamide (theanine) treatment on delayed neuronal death in transient forebrain ischemia of gerbils. Theanine was administered daily 5 mg/kg alter ischemia for 30 days. After survival of 30 days, the extent of CA1 neuronal damage in the hippocampus was assessed histologically. Short-duration and mild postischemic hypothermia combined with theanine treatment led to significant increase (67% and 72%, respectively) in viable CA1 neurons, compared to the control group (8% survival). These findings indicate that short-duration and mild hypothermia in combination with theanine has a beneficial effect on ischemic neuronal damage consistently. Less