重复伤害性电刺激下大鼠脑功能性磁共振成像的变化

FUNCTIONAL MAGNETIC RESONNANCE IMAGING OF BRAIN ACTIVATION DURING REPEATED NOXIOUS ELECTRICAL STIMULATION IN RATS

目的:观察重复伤害性电刺激下大鼠脑功能磁共振成像的变化。方法:健康清洁级SD大鼠24只,麻醉后行4个相同时间段的左前爪重复伤害性电刺激(分别为A、B、C、D,刺激间期为10 min);刺激期间予脑功能磁共振成像扫描,用统计参数法行图像分析不同时间段伤害性电刺激下脑功能成像的变化。结果:不同时间段刺激鼠左前爪激活数目情况:D时间段的总的激活数目显著低于A、B、C时间段,差异有统计学意义(P<0.05);C时间段总的激活数目显著低于A、B时间段,差异有统计学意义(P<0.05)。A、B、C、D时间段伤害性电刺激大鼠均存在明显的局部脑区的血氧水平依赖(blood-oxygenation level-dependent,BOLD)信号的强烈变化,主要激活脑区包括:伏膈核(accumbens nucleus,Acb)、右侧初级感觉皮质(primary somatosensory cortex,SI)、右侧腹后外侧丘脑核(ventral posterolateral thalamic nucleus,VPL)及后扣带回皮质(retrosplenial granular cortex,RSG);在重复伤害性电刺激后,中枢对电刺激引起的躯体感觉传导通路及加工网络的BOLD信号响应减弱。结论:重复伤害性电刺激后,大鼠脑功能成像显示激活脑区数目减少,伏膈核、右侧S1、VPL、RSG脑区激活体素减小,可能与中枢对伤害性刺激的调制有关。

Objective： To observe the changes in rat brain after repeated electric nociception stimulas with Functional magnetic resonance imaging （fMRI）. Methods： 24 rats were suffered 4 intervals noxious electric stimulus in left forepaw, and whole brain scanning imaging were acquired. Post-processed images were analysed with SPM2 using a multi-subject fixed effects general linear model, to characterize brain specific activations and visualise cerebral processing network activation of nociception stimulation at different intervals. Rusults： The sum amounts of activation during C stage were decreased significantly after 2 stage-constant current electrical stimulation （P 〈 0.05）. The sum amounts of activation during D stage were decreased significantly after 3 stage-constant current electrical stimulation （P 〈 0.05）. The amounts of brain activation during D stage were deceased significantly after 3 stage-constant current electrical stimulation （P 〈 0.05）. The brain activation included Acb, SI （right）, VPL and RSG. After 3 stage-constant current electrical stimulation, The blood-oxygenation level-dependent （BOLD） responses of rat brain were decreased. Conclusion： After repeated nociceptive electrical stimulation, the number of activated brain areas and the activated voxels in Acb, the right S 1, VPL and RSG decreased in rat brain by functional magnetic resonance imaging, which may be related to the central modulation of nociceptive stimulation.