丙酚对大鼠皮层和丘脑脑电非线性参数的影响

目的：研究不同浓度的异丙酚对大鼠顶区、额区、枕区和丘脑腹后内侧核（VPM）脑电近似熵（ApEn）和关联维数（D2）的影响.方法：48只雄性SD大鼠随机分为4组（n=12）,分别在左右顶区、额区、枕区和丘脑VPM埋置硬膜外和深部电极,连续监测自发EEG.记录20min清醒状态的基础EEG后,持续静脉输注10g/L异丙酚,浓度依次为400,500,600,700,800,900μg/（kg·min）,每个浓度持续输注10min,取最后2min的EEG进行后期分析,计算不同异丙酚浓度时各脑区的ApEn和D2.埋置电极进行EEG监测的前1wk,分别测量使大鼠翻正反射消失和夹尾反射消失的异丙酚浓度.结果：随着异丙酚药物浓度的增加,左右顶区、额区、枕区和丘脑的ApEn和D2均逐渐降低.所有大鼠均在500～600μg/（kg·min）时翻正反射消失,在800～900μg/（kg·min）时夹尾反射消失,产生以上不同麻醉效应的异丙酚浓度对应的各脑区ApEn和D2均低于清醒状态.结论：异丙酚可浓度依赖地降低顶区、额区、枕区和丘脑VPM活动的复杂程度,ApEn和D2是敏感的与不同麻醉效应相关的非线性EEG参数.

Effects of propofol on nonlinear parameters of EEG in the rat

AIM：To investigate the effects of propofol on electroencephalogram（EEG）approximate entropy（ApEn）and correlation dimension（D2）in the rat.METHODS：Forty-eight male Sprague-Dawley rats were divided into 4 groups randomly（n=12）,whose EEGs were recorded bipolarly with pairs of epidural electrodes in the left and right parietal cortices,frontal cortices,occipital cortices and ventral posteromedial thalamic nucleus（VPM）respectively.Anesthetic concentration of propofol was started at 400 μg/（kg·min）and then rised in four increments to 900 μg/（kg·min）while the rats were breathing spontaneously.A 10 min period was allowed at each concentration level.Calculated and compared interhemispheric EEGs ApEn and D2 of different encephalic region at different concentration level.And in all the rats the loss of righting reflex and the loss of tail-clamped reflex as a function of anesthetic concentration was tested a week before the animals were subjected to be placed the epidural electrodes.RESULTS：EEG ApEn and D2 of parietal cortices,frontal cortices,occipital cortices and thalamic VPM dose-dependently decreased as propofol concentration increased.ApEn and D2 of all the encephalic region fell below the awake baseline at 600 μg/（kg·min）and 900 μg/（kg·min）anesthetic concentration that also abolished the righting reflex and the tail-clamped reflex respectively.CONCLUSION：Propofol dose-dependently decrease the functional states of parietal cortices,frontal cortices,occipital cortices and thalamic VPM,and ApEn and D2 are both sensitive correlates of different anesthetic effects of propofol.