脑缺血时大鼠大脑皮层乙酰胆碱含量变化的动态观察

DYNAMIC OBSERVATION ON CHANGES OF ACETYLCHOLINE IN RAT CEREBRAL CORTEX DURING CEREBRAL ISCHEMIA

本实验采用双侧颈总动脉夹闭（ＣＣＡＯ）和大脑中动脉闭塞（ＭＣＡＯ）两种脑缺血动物模型，分别用乙酰胆碱（ＡＣｈ）生物测定法检测皮层ＡＣｈ含量，ＡＣｈ离子选择性微电极（ＡＣｈ－ＩＳＭｓ）检测皮层ＡＣｈ释放量，乙酰胆碱酯酶（ＡＣｈＥ）生化测定法检测皮层ＡＣｈＥ活性，观察脑缺血时皮层ＡＣｈ含量的动态查化。结果发现：脑缺血可诱发皮层ＡＣｈ活度急剧上升，示ＡＣｈ突然大量释放，在ＣＣＡＯ组于缺血１０ｍｉｎ达到高峰（净增１．４４４ｍｍｏｌ／Ｌ），而ＭＣＡＯ组于缺血２ｍｉｎ即达高峰（净增１．５５３ｍｍｏｌ／Ｌ），随着缺血延长，二者均逐渐下降，于缺血３０ｍｉｎ时，虽较峰值要低，但明显高于缺血前水平，此时，ＡＣｈＥ活性巳明显低于缺血前，ＡＣｈ含量在ＣＣＡＯ组下降０．２５６μｇ／ｇ（Ｐ＞０．０５），在ＭＣＡＯ组则显著下降１．０１４μｇ／ｇ（Ｐ＜０．０１）。结果提示：皮层ＡＣｈ含量变化对缺血是敏感的；脑缺血时ＡＣｈ含量下降、释放增加、降解减弱，推测ＡＣｈ可能在缺血性脑损伤中起重要作用。

The present study applied acetylcholine (ACh) bioassay to measure ACh content.acetylcholinesterase (AChE) biochemical method to determine AChE activity and ACh ion selective microelectrodes (ACh-ISMs) to measure ACh output in rat cerebral cortex, clarified changes of ACh in ischemic cortex induced by two rat models of cerebral ischemia - common carotid artery occlusion (CCAO), middle cerebral artery occlusion (MCAO). The results showed ACh output increased to peak in 10 min after ischemia induced by CCAO (raised 1.444 mmol/ L netly), but to summit in 2 min after MCAO (raised 1.553 mmol/ L netly). However ACh cutout appeared a trend to decline along with lengthening of ischemia in two models.30 min after ischemia, ACh activities were lower than peak, but high than per-ischemia's, ACh contents and AChE activities were low to pre-ischemia's. This research indicated that ACh in rat cerebral cortex was sensitive to ischemia; the falled extent of ACh content and the raised velocity of ACh output were positively correlative to the degree of cerebral ischemia; ACh could take some important effects on ischemic brain injury.