氯胺酮麻醉下犬不同脑区神经递质的变化

摘　　要: 目的：探讨氯胺酮麻醉时犬脑内皮层区和丘脑多种神经递质的动态变化，揭示氯胺酮麻醉中枢作用的可能机制。方法：应用磁共振波谱分析（magnetic resonance spectroscopy, MRS）技术，选取12只犬，每只犬先后行3次MRS扫描，第1次在清醒状态下扫描作为自身对照，第2、3次分别通过静脉输入氯胺酮1mg／kg和 2mg／kg后进行，采集感兴趣区（regions of interest）皮层运动区和丘脑内渡谱。分析测定N-乙酰基天门冬氨酸（NAA）、谷氨酸（Glu）、γ-氨基丁酸（GABA）、胆碱类化合物（Cho）和肌酸（Cr）的动态变化。结果：与清醒状态相比，氯胺酮镇静状态下，NAA、Glu、Cho在丘脑、皮层呈下降趋势（P 〈0．05）；GABA、Cr在上述2个区域均无显著变化。与清醒状态相比，氯胺酮麻醉状态下，NAA、Glu、Cho在皮层和丘脑显著下降（P 〈0．01）；Cr、GABA在皮层和丘脑没有明显的变化。结论：皮层和丘脑内多种递质代谢的变化与氯胺酮的麻醉作用密切相关．氯胺酮的麻醉作用主要是对 NAA、Glu、Cho的抑制作用。

Imaging study on the effect of ketamine on neurotransmitter metabolism with 1H-mgnetic resonance spectrography in dogs

Objective With the proton magnetic resonance spectroscopy technology,to investigate the changes of diverse neurotransmitter metabolism in sensory cortex and thalamus produced by ketamine in dogs,and to reveal the mechanism of ketamine.Methods Twelve healthy dogs,each of the dogs underwent MRS scaned for three times,including before(dogs being the concious state) and after the intravenous injection of ketamine of 1.0 mg /kg and 2.0 mg /kg.The scans on sensory cortex and thalamencephalon were employed by 1.5T magnetic resonance imaging system of Phlips Intera Master.The spectra concerned were collected,including sensory cortex,thalamus regions,and the dynamic changes of NAA,Glu,GABA,Cho and Cr were determined and analyzed.Results Compared with the conscious state,NAA,Glu,Cho in both sensory cortex and thalamus decreased significantly after intravenous infection of ketamine of 1 mg /kg or 2 mg /kg,and there were no significant changes of GABA and Cr.Conclusion Ketamine can revoke the metabolic changes of many neurotransmitters,mainly inhibiting the releases of the NAA,Glu and Cho in sensory cortex and thalamus,and then achieve the anesthetic role.