HMGB1在高血糖加重脑缺血再灌注损伤中的作用及机制探讨

发布时间：2018-02-26 19:23

本文关键词： 高迁移率族蛋白B1 血—脑脊液屏障高血糖脑缺血再灌注损伤　出处：《山东大学》2014年硕士论文　论文类型：学位论文

【摘要】：研究背景：脑卒中是常见病、多发病,而其中又以大脑中动脉梗塞造成的脑缺血尤为常见。缺血性脑卒中同样存在着非常高的致死率和致残率。阻塞血管的再通在缺血性脑卒中的治疗中,对于缺血周边区域脑组织损伤的修复是非常重要的,但是它带来的问题——缺血性再灌注损伤,也是目前关注最多的。临床研究结果发现,缺血性脑卒中的患者当中,有很大一部分患者的血糖增高。引起高血糖原因,目前还没有完全阐明,大多认为是糖尿病或者是应激性反应的表现。高血糖致使脑卒中患者的死亡率、致残率增高并且延长神经功能恢复时间。因此,高血糖已成为缺血性脑卒中患者预后的一个独立性预测指标。然而高血糖与缺血性再灌注损伤(CIRI)之间的关系目前尚不清楚,究竟是高血糖本身可诱发并加重缺血性再灌注损伤(CIRI)呢?还是高血糖仅仅是缺血性脑卒中(ICS)预后差的一个指标,尚需要实验进一步证实。高血糖加重CIRI的确切机制亦尚未阐明。HMGB1是近年来研究比较多的炎症因子,有研究表明,HMGB1可以通过破坏BBB参与缺血性脑损伤中,而且应用HMGB1特异性抑制剂则可显著减轻BBB损伤。HMGB1在正常脑细胞外低表达,但在脑缺血损伤时,细胞外HMGB1迅速升高,胞外的HMGB1可以作为一种重要的炎症介质,诱导、维持和延长炎症过程。随着神经炎症的发展,由脑内星形胶质细胞与血管内皮细胞形成的紧密连接所构成的血脑屏障的破坏加剧,引起脑水肿。虽然,目前HMGB1在其他器官的缺血性再灌注损伤中的作用机制的文献报道比较多,但它在脑缺血再灌注损伤方面研究的不多,特别是在急性高血糖加重缺血性脑损伤中的作用机制方面报道较少。研究目的：拟建立MCAO模型,探讨HMGB1在急性高血糖加重脑缺血再灌注损伤中的作用及其机制。研究方法：实验动物wistar大鼠60只,随机分为假手术(sham)组、正常血糖(NG)组及加HMGB1抑制剂(GL)(NG+GL)组、高血糖(HG)组和加HMGB1抑制剂GL (HG+GL)组,共五组。于缺血90min再灌注后2h、4h用westernblot检测脑脊液中HMGB1含量、4h时用伊文思蓝(Evans blue, EB)检测血脑屏障的通透性、4h时用westernblot检测脑组织中HMGB1和occludin含量变化,24h时TTC检测脑水肿和脑梗死体积,24h时评估神经功能缺失。研究结果：EB外渗率,以及脑梗死范围和脑水肿均明显加重(P0.01),神经功能评分明显降低(P0.05),HG组大鼠脑脊液中HMGB1含量显著提高(P0.01)；脑组织中的Occludin含量明显降低；采用HMGB1特异性的抑制剂GL治疗后,上述指标显著改善(P0.01)。结论：在缺血性脑卒中合并高血糖时,可能通过HMGB1释放增加导致BBB破坏加重,从而加重脑损伤。而HMGB1特异性的抑制剂有保护作用。
[Abstract]:Background: stroke is a common disease. Among them, cerebral ischemia caused by middle cerebral artery infarction is particularly common. Ischemic stroke also has a very high mortality and disability rate. The recanalization of blocked blood vessels is used in the treatment of ischemic stroke. It is very important for the repair of cerebral tissue injury in the ischemic peripheral region, but it brings the problem of ischemic reperfusion injury, which is the most concerned at present. The clinical research results show that among the patients with ischemic stroke, There is a large proportion of patients with hyperglycemia. The causes of hyperglycemia have not been fully elucidated yet, most of them are considered to be signs of diabetes or stress response. Hyperglycemia results in the death rate of stroke patients. As a result, hyperglycemia has become an independent predictor of prognosis in patients with ischemic stroke. However, the relationship between hyperglycemia and ischemic reperfusion injury (CIRI) is unclear. Is it the hyperglycemia itself that induces and exacerbates ischemic reperfusion injury (CIRI)? Whether hyperglycemia is only a poor prognostic indicator of ischemic stroke needs to be further confirmed by experiments. The exact mechanism of hyperglycemia exacerbating CIRI has not been elucidated. HMGB1 is an inflammatory factor which has been studied in recent years. Some studies have shown that HMGB1 can participate in ischemic brain injury by destroying BBB, and the application of HMGB1 specific inhibitor can significantly attenuate the low expression of HMGB1 outside normal brain cells, but during cerebral ischemia injury, extracellular HMGB1 increases rapidly. Extracellular HMGB1 can act as an important inflammatory mediator that induces, maintains, and prolongs the inflammatory process. The destruction of the blood-brain barrier formed by the tight connection between astrocytes and vascular endothelial cells in the brain increases, causing brain edema. At present, there are many reports about the mechanism of HMGB1 in the ischemic reperfusion injury of other organs, but it has not been studied much in the field of cerebral ischemia-reperfusion injury. Especially in the acute hyperglycemia exacerbation of ischemic brain injury in the role of less reported. Objective: to establish MCAO model to investigate the role and mechanism of HMGB1 in acute hyperglycemia exacerbating cerebral ischemia-reperfusion injury. Methods: sixty wistar rats were randomly divided into three groups: sham group, normal blood glucose group, HMGB1 inhibitor GLG group, hyperglycemia group and HMGB1 inhibitor GLG group. The content of HMGB1 in cerebrospinal fluid (CSF) was detected by westernblot at 4 h after ischemia and reperfusion. The permeability of blood-brain barrier was detected by westernblot for 4 h and the contents of HMGB1 and occludin in brain tissue were detected by westernblot. The contents of HMGB1 and occludin in brain tissue were detected by TTC for 24 h. Neurological deficit was evaluated at 24 h after cerebral infarction. Results the percentage of exosmosis, the size of cerebral infarction and cerebral edema were significantly increased in the control group (P 0.01). The neurologic function score significantly decreased the content of HMGB1 in cerebrospinal fluid (CSF) and the content of Occludin in brain tissue (P 0.01) in the HG group. After treatment with GL, a specific inhibitor of HMGB1, the above indexes were significantly improved (P 0.01). Conclusion: in ischemic stroke complicated with hyperglycemia, BBB damage may be aggravated by increasing HMGB1 release, while HMGB1 specific inhibitors have protective effect.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R743.3

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