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| 全身亚低温和选择性脑亚低温减轻大鼠脑缺血-再灌注损伤的比较 |
| Comparison of systemic mild hypothermia and selective brain mild hypothermia on reducing cerebral ischemia-reperfusion injury in rats |
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| DOI：10.12089/jca.2022.02.015 |
| 中文关键词: 全身亚低温 选择性脑亚低温 缺血-再灌注 大鼠 |
| 英文关键词: Systemic mild hypothermia Selective brain mild hypothermia Ischemia-reperfusion injury Rat |
| 基金项目:青岛市科技民生项目（19-6-1-50-nsh） |
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| 中文摘要: |
目的 比较全身亚低温和选择性脑亚低温减轻大鼠脑缺血-再灌注损伤的效果。
方法 清洁级健康雄性SD大鼠80只，8周龄，体重200～250 g。采用随机数字表法分为四组：假手术组（S组）、缺血-再灌注组（IR组）、全身亚低温组（T组）和选择性脑亚低温组（H组），每组20只。四组大鼠在监测脑温及直肠温度下进行操作。S组仅暴露颈部血管；IR组采用线栓法建立脑缺血-再灌注损伤（CIRI）大鼠模型，阻断大鼠左侧大脑中动脉2 h后恢复血流灌注；T组建立CIRI大鼠模型后，拔除线栓即刻将75%乙醇直接均匀泼洒到全身皮肤降温；H组建立CIRI大鼠模型后，拔除线栓即刻于左侧颈内动脉以80 ml·kg-1·h-1的速度注入4 ℃生理盐水。记录T组和H组大鼠的降温时间（脑温降至33 ℃的时间）、脑达到亚低温时肛温及脑亚低温维持时间。记录再灌注后24 h改良神经功能缺损严重程度评分（mNSS）。完成mNSS后处死大鼠，采用TTC染色法观察大脑梗死情况并计算脑梗死容积百分比，TUNEL法检测神经细胞凋亡率，HE染色观察神经细胞形态改变，透射电镜下观察线粒体超微结构改变。
结果 与S组比较，IR组、T组和H组mNSS、脑梗死容积百分比、神经细胞凋亡率明显升高（P<0.05）。与IR组比较，T组和H组mNSS、脑梗死容积百分比、神经细胞凋亡率明显降低（P<0.05）。与T组比较，H组达到脑亚低温的时间明显缩短（P<0.05），mNSS、脑梗死容积百分比、神经细胞凋亡率明显降低（P<0.05）。HE染色观察到S组大鼠神经细胞形态完整且轮廓清晰；IR组见大量细胞水肿，细胞核不规则浓缩；T组细胞水肿减轻；H组细胞形态改变进一步减轻。透射电镜下S组线粒体形态正常，呈圆状或杆状，双层膜结构完整，无肿胀和空泡变性；IR组线粒体肿胀变圆，部分可见嵴断裂和空泡化现象；T组线粒体肿胀和空泡变性减轻；H组线粒体形态改变进一步减轻。
结论 全身亚低温和选择性脑亚低温均能减轻大鼠脑缺血-再灌注损伤，经颈动脉灌注低温生理盐水实现选择性脑亚低温降温速度快，减轻大鼠脑缺血-再灌注的效果更好。 |
| 英文摘要: |
Objective To compare the effects of systemic mild hypothermia and selective brain mild hypothermia on reducing cerebral ischemia-reperfusion injury in rats.
Methods Eighty clean healthy male Sprague-Dawley rats, aged 8 weeks, weighing 200-250 g, were divided into 4 groups using random number table method: sham operation group (group S), ischemia-reperfusion group (group IR), systemic mild hypothermia group (group T) and selective brain mild hypothermia group (group H), 20 rats in each group. Four groups were operated under the monitoring of brain temperature and rectal temperature. Only the cervical blood vessels were exposed in group S, while the left middle cerebral artery were blocked for 2 hours following reperfusion in the other three groups. In group T, 75% ethanol was directly evenly sprayed onto the skin immediately following the withdrawal of thread plug, while 4 ℃ normal saline was injected via the left internal carotid artery at a rate of 80 ml·kg-1·h-1 in group H. Record the time duration of brain temperature reaching 33 ℃, anal temperature of brain at mild hypothermia, and the maintenance time of mild hypothermia in groups T and H, and modified neurological severity score (mNSS) 24 hours after reperfusion. The percentage of infarct volume tested by TTC staining, cell morphological changes observed by HE staining, nerve cell apoptosis rate tested by TUNEL staining, and mitochondrial ultrastructure observed by transmission electron microscope were recorded.
Results Compared with group S, mNSS, percentage of infarct volume in the left cerebral cortex, and cellular apoptosis rate in the ischemic penumbra area were significantly increased in groups IR, T and H (P < 0.05). Compared with group IR, mNSS, percentage of infarct volume, and cellular apoptosis rate were significantly increased in groups T and H (P < 0.05). Compared with group T, the cooling time in group H was shortened (P < 0.05), mNSS, percentage of infarct volume, and cellular apoptosis rate were significantly decreased in group H (P < 0.05). HE staining showed that the neurocytes in group S had integrated morphology and clear contours, while a large amount of cellular edema and irregularly concentrated cells in the ischemic penumbra area were observed in group IR. The degree of cellular edema in group T was reduced, and the morphological changes in group H were further reduced. Under transmission electron microscope, the morphology and structure of mitochondria in group S are normal, with round or rod-shaped shape and intact double-layer membrane, and without swelling and vacuolar degeneration. The mitochondria in group IR swelled and rounded, with crista rupture and cavitation partially. The mitochondria in group T appeared less swollen and less vacuolar degeneration, and the degenerative morphological changes of mitochondria in group H were further reduced.
Conclusion Both selective brain mild hypothermia and systemic mild hypothermia could alleviate cerebral ischemia-reperfusion injury in rats. Selective brain mild hypothermia achieved by cold physiological saline infusion via carotid artery brought stronger cooling efficiency and better protective effects against CIRI． |
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