Abstract:

Objective To assess the effect of large-dose hyperbaric oxygenation (HBO) on cell apoptosis of permanent middle cerebral artery occlusion (MCAO) rats in super-early stage. Methods Seventy-two male Sprague-Dawley rats were subjected to permanent MCAO model using the intraluminal suture method, then the rats were randomly divided into control group and HBO group (n =36). Three hours after MCAO, the rats in the HBO group stayed in the hyperbaric cabin with a pressure of 0.2 MPa for 9 h. Neurological outcome was measured using Garcia scores on 3 h、13 h and 72 h after MCAO. Brain tissue was stained by tetrazolium chloride (TTC) and the volume of infarction was calculated on 13 h and 72 h. Apoptosis cells of ischemic penumbra tissue were investigated by terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) on 13 h and 72 h. Mitochondrial membrane potential (MMP) was measured by flow cytometry on 13 h and 72 h. Results (1) The scores were higher on 13 h (both P =0.007) and 72 h (both P <0.001) compared to that of 3 h in both groups. The HBO group has the better trend, but there was no significant difference between groups (P >0.05). (2) There was no significant difference in the infarct volume between two groups on 13 h (P >0.05), and the volume of control group on 72 h was larger than that on 13 h (P =0.02), while the volume in HBO group was smaller than that in control group on 72 h (P =0.02). (3) The apoptosis cells can be seen in both groups on 13 h and 72 h. The apoptosis cells of HBO group were less than control group on 13 h (P =0.04). (4) The MMP of control group reduced after MCAO which was lower than that in HBO group at all time points (both P <0.001). Conclusion Large-dose HBO protocol in super-early stage can improve neurological function score, reduce the volume of cerebral infarction in rats. Inhibiting the MMP, and then reducing cell apoptosis may be one of the mechanisms.

Key words: Hyperbaric oxygenation; Cerebral infarction; Neurological scores; Cell apoptosis; Mitochondrial membrane potential

摘要：

目的 观察大剂量高压氧（hyperbaric oxygenation，HBO）超早期治疗对永久性大脑中动脉阻塞 （middle cerebral artery occlusion，MCAO）大鼠细胞凋亡的影响。 方法 制作SD大鼠永久性MCAO模型，随机分为对照组（n =36）和HBO组（n =36），HBO组大鼠于模型 制备成功后3 h予单次9 h HBO治疗，压力0.2 MPa。于模型成功后3 h、13 h、72 h，行大鼠Garcia神经功 能评分，于13 h、72 h分别将大鼠脑组织进行2，3，5苯四氮唑（tetrazolium chloride，TTC）染色测定梗 死容积百分比，应用脱氧核糖核苷酸末端转移酶介导的缺口末端标记法（terminal-deoxynucleotidyl transferase mediated nick end labeling，TUNEL）检测细胞凋亡，流式细胞仪检测线粒体膜电位。 结果 ①两组大鼠在MCAO 13 h时（P均=0.007）和72 h时（P均＜0.001）均较同组MCAO 3 h时神经功 能明显改善，但各时间点两组间神经功能无显著差异。②13 h时，两组大鼠脑梗死容积比无显著差异； 72 h时，对照组大鼠脑梗死容积比较13 h时增大（P =0.02），而HBO组无显著变化，HBO组较对照组脑 梗死容积比小（P =0.02）。③HBO组及对照组在13 h、72 h均可见凋亡细胞，13 h时HBO组凋亡细胞数少 于对照组（P =0.04）。④大鼠MCAO后线粒体膜电位降低，HBO组在13 h、72 h的线粒体膜电位均高于对 照组，差异有显著性（P均＜0.001）。 结论 大剂量HBO超早期治疗可缩小大鼠脑梗死容积，抑制线粒体膜电位降低，进而减少细胞凋亡 可能是高压氧治疗脑梗死的机制之一。

关键词: 高压氧; 脑梗死; 神经功能评分; 细胞凋亡; 线粒体膜电位