NADH fluorescence imaging and the histological impact of cortical spreading depolarization during the acute phase of subarachnoid hemorrhage in rats
NADH fluorescence imaging and the histological impact of cortical spreading depolarization during the acute phase of subarachnoid hemorrhage in rats
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DOI：
10.3171/2016.9.jns161385
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发表时间：
2018-01-01
影响因子：
4.1
通讯作者：
Date, Isao
中科院分区：
文献类型：
--
作者：
Shimizu, Tomohisa;Hishikawa, Tomohito;Date, Isao
目的：虽然在临床蛛网膜下腔出血（SAH）的早期阶段观察到皮质扩张性去极化（CSD），但CSD的致病性尚不清楚。本研究的目的是阐明膜电位丧失对急性期SAH神经元损伤的影响。方法采用穿孔法对24只大鼠进行SAH治疗。在顶叶-颞叶皮层暴露于紫外光下，利用电极监测2个直流（DC）电位，获得NADH（还原性烟酰胺腺嘌呤二核苷酸）荧光图像，研究大脑皮层去极化的传播。在侧电极附近监测脑血流量（CBF）。SAH发病24小时后，在DC电位记录部位评估组织学损伤。结果根据SAH诱导后全脑缺血去极化的表现，将48例脑直流电电位的变化分为3种类型。在1型变化（n = 21）中，在1小时的观察期内未观察到缺血性去极化。在2型变化（n = 13）中，DC电位在SAH开始时表现出缺血去极化，并在1小时的观察期间（33.3 +/- 15.8分钟）从最大DC偏转中恢复80%。在3型变化（n = 14）中，直流电电位表现为缺血去极化，在1小时的观察期间未恢复。在直流电位记录部位的组织学评估显示，1型组中所有部位的组织都完好无损，而在2型和3型组中，根据缺血去极化的持续时间，观察到不同程度的神经元损伤。去极化导致50%神经元损伤的持续时间（P-50）估计为22.4分钟（95%置信区间为17.0-30.3分钟）。1型组3只大鼠在SAH发生5.1 +/- 2.2分钟后6个部位出现CSD。在NADH荧光图像上，最初在前皮层观察到CSD；它以3毫米/分钟的速率向枕叶皮层方向通过整个半球传播，在2.3 +/- 1.2分钟内发生复极化。24小时后发现接受CSD的直流电位记录部位组织完整。与去极化造成50%的神经元损伤相比，CSD持续时间太短，不会造成组织学损伤。结论利用NADH荧光成功地观察到CSD。随着脑血流的增加，它从前皮层向后皮层扩散。CSD的去极化持续时间（2.3 +/- 1.2分钟）远短于造成50%神经元损伤的去极化持续时间（22.4分钟），并且在目前的实验环境中与组织学损伤无关。
OBJECTIVE Although cortical spreading depolarization (CSD) has been observed during the early phase of subarachnoid hemorrhage (SAH) in clinical settings, the pathogenicity of CSD is unclear. The aim of this study is to elucidate the effects of loss of membrane potential on neuronal damage during the acute phase of SAH.METHODS Twenty-four rats were subjected to SAH by the perforation method. The propagation of depolarization in the brain cortex was examined by using electrodes to monitor 2 direct-current (DC) potentials and obtaining NADH (reduced nicotinamide adenine dinucleotide) fluorescence images while exposing the parietal-temporal cortex to ultraviolet light. Cerebral blood flow (CBF) was monitored in the vicinity of the lateral electrode. Twenty-four hours after onset of SAH, histological damage was evaluated at the DC potential recording sites.RESULTS Changes in DC potentials (n = 48 in total) were sorted into 3 types according to the appearance of ischemic depolarization in the entire hemisphere following induction of SAH. In Type 1 changes (n = 21), ischemic depolarization was not observed during a 1-hour observation period. In Type 2 changes (n = 13), the DC potential demonstrated ischemic depolarization on initiation of SAH and recovered 80% from the maximal DC deflection during a 1-hour observation period (33.3 +/- 15.8 minutes). In Type 3 changes (n = 14), the DC potential displayed ischemic depolarization and did not recover during a 1-hour observation period. Histological evaluations at DC potential recording sites showed intact tissue at all sites in the Type 1 group, whereas in the Type 2 and Type 3 groups neuronal damage of varying severity was observed depending on the duration of ischemic depolarization. The duration of depolarization that causes injury to 50% of neurons (P-50) was estimated to be 22.4 minutes (95% confidence intervals 17.0-30.3 minutes). CSD was observed in 3 rats at 6 sites in the Type 1 group 5.1 +/- 2.2 minutes after initiation of SAH. On NADH fluorescence images CSD was initially observed in the anterior cortex; it propagated through the entire hemisphere in the direction of the occipital cortex at a rate of 3 mm/minute, with repolarization in 2.3 +/- 1.2 minutes. DC potential recording sites that had undergone CSD were found to have intact tissue 24 hours later. Compared with depolarization that caused 50% neuronal damage, the duration of CSD was too short to cause histological damage.CONCLUSIONS CSD was successfully visualized using NADH fluorescence. It propagated from the anterior to the posterior cortex along with an increase in CBF. The duration of depolarization in CSD (2.3 +/- 1.2 minutes) was far shorter than that causing 50% neuronal damage (22.4 minutes) and was not associated with histological damage in the current experimental setting.