Luckl Janos, Baker Wesley, Sun Zheng-Hui, Durduran Turgut, Yodh Arjun G, Greenberg Joel H
Department of Neurology, University of Pennsylvania Philadelphia, PA, USA.
Front Neuroenergetics. 2010 Jul 30;2. doi: 10.3389/fnene.2010.00019. eCollection 2010.
Our group has already published the possible neuroprotective effect of contralateral forepaw stimulation in temporary focal ischemia in a study. However, the background is still unclear. In the present study we investigated the possible mechanism by monitoring focal ischemia with multispectral [laser speckle, imaging of intrinsic signals (OIS)] imaging. Sprague-Dawley rats were prepared using 1.2% isoflurane anesthesia. The middle cerebral artery was occluded by photothrombosis (4 mW) and the common carotid artery was ligated permanently. Physiological variables were constantly monitored during the experiment. A 6 x 6 mm area centered 3 mm posterior and 4 mm lateral to Bregma was thinned for laser speckle and OIS imaging. Nine circular regions of interests (0.3 mm in diameter) were evenly spaced on the speckle contrast image for the analysis of peri-infarct flow transients, blood flow, and metabolic changes. Both the sham (n = 7) and forepaw-stimulated animals (n = 7) underwent neurological examinations 24 h after ischemia at which point all animals were sacrificed and the infarct size was determined by triphenyltetrazolium chloride. The physiological variables were in normal range and the experimental protocol did not cause significant differences between groups. Both the neurological scores (sham: 3.6 +/- 1.7, stimulated: 4.3 +/- 1.4) and the infarct volume (sham: 124 +/- 39 mm(3), stimulated: 147 +/- 47 mm(3)) did not show significant differences between groups. The forepaw stimulation did not increase the intra-ischemic flow neither over the penumbral or the peri-ischemic area. However, the hemoglobin transients related metabolic load (CMRO(2)) was significantly lower (p < 0.001) while the averaged number of hyperemic flow transients were significantly (p = 0.013) higher in the forepaw (sham: 3.5 +/- 2.2, stimulated: 7.0 +/- 2.3) stimulated animals.
我们小组已经在一项研究中发表了关于对侧前爪刺激在短暂性局灶性缺血中可能具有的神经保护作用。然而,其背景仍不清楚。在本研究中,我们通过多光谱[激光散斑、内在信号成像(OIS)]成像监测局灶性缺血,来研究其可能的机制。使用1.2%异氟烷麻醉制备Sprague-Dawley大鼠。通过光血栓形成(4毫瓦)闭塞大脑中动脉,并永久性结扎颈总动脉。实验过程中持续监测生理变量。在脑前囟后方3毫米和外侧4毫米处,以其为中心划出一个6×6毫米的区域,将其变薄以进行激光散斑和OIS成像。在散斑对比图像上均匀分布九个直径为0.3毫米的圆形感兴趣区域,用于分析梗死周边血流瞬变、血流量和代谢变化。假手术组(n = 7)和前爪刺激组动物(n = 7)在缺血24小时后均接受神经学检查,此时所有动物均被处死,通过氯化三苯基四氮唑确定梗死面积。生理变量处于正常范围,实验方案未导致组间出现显著差异。神经学评分(假手术组:3.6±1.7,刺激组:4.3±1.4)和梗死体积(假手术组:124±39立方毫米,刺激组:147±47立方毫米)在组间均未显示出显著差异。前爪刺激并未增加缺血区内半暗带或缺血周边区域的血流。然而,在前爪刺激组动物中,与血红蛋白瞬变相关的代谢负荷(CMRO₂)显著更低(p < 0.001),而充血性血流瞬变的平均数量显著更高(p = 0.013)(假手术组:3.5±2.2,刺激组:7.0±2.3)。
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