Ketamine and Xylazine depress sensory-evoked parallel fiber and climbing fiber responses
Ketamine and Xylazine depress sensory-evoked parallel fiber and climbing fiber responses
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DOI：
10.1152/jn.00057.2007
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发表时间：
2007-09-01
影响因子：
2.5
通讯作者：
Joerntell, Henrik
中科院分区：
文献类型：
--
作者：
Bengtsson, Fredrik;Joerntell, Henrik
近年来，用于研究小脑生理机制的体内实验种类有所增加。氯胺酮和噻嗪的组合已经成为一种特别流行的麻醉形式。然而，由于这些实验缺乏非麻醉的对照条件，目前还没有对这些药物对小脑神经网络生理活动的影响进行评估。在本研究中，我们以非麻醉、去脑大鼠的苔藓纤维、平行纤维和攀爬纤维场电位作为对照条件，比较静脉注射药物的作用。所有麻醉药均按正常麻醉维持所需剂量施用。我们发现氯胺酮显著降低了平行纤维突触活性指标N3场电位（- 40%），几乎完全消除了诱发攀登纤维场电位（- 90%）。Xylazine严重抑制N3区（- 75%），完全抑制攀援纤维区（- 100%）。在通常用于全身麻醉（20:1）的组合中，氯胺酮-羟嗪注射也严重抑制了N3区（- 75%），几乎完全消除了攀爬纤维区（- 90%）。我们还观察到，身体和表面温度的降低（- 34摄氏度）导致N3场的大幅凹陷（- 50%）。这些结果敦促在解释用这些药物麻醉的动物的小脑网络生理学研究时要谨慎一些。
The last few years have seen an increase in the variety of in vivo experiments used for studying cerebellar physiological mechanisms. A combination of ketamine and xylazine has become a particularly popular form of anesthesia. However, because nonanesthetized control conditions are lacking in these experiments, so far there has been no evaluation of the effects of these drugs on the physiological activity in the cerebellar neuronal network. In the present study, we used the mossy fiber, parallel fiber, and climbing fiber field potentials evoked in the nonanesthetized, decerebrated rat to serve as a control condition against which the effects of intravenous drug injections could be compared. All anesthetics were applied at doses required for normal maintenance of anesthesia. We found that ketamine substantially depressed the evoked N3 field potential, which is an indicator of the activity in the parallel fiber synapses (- 40%), and nearly completely abolished evoked climbing fiber field potentials ( - 90%). Xylazine severely depressed the N3 field ( - 75%) and completely abolished the climbing fiber field ( - 100%). In a combination commonly used for general anesthesia ( 20: 1), ketamine-xylazine injections also severely depressed the N3 field ( - 75%) and nearly completely abolished the climbing fiber field ( - 90%). We also observed that lowered body and surface temperatures ( - 34 degrees C) resulted in a substantial depression of the N3 field ( - 50%). These results urge for some caution in the interpretations of studies on cerebellar network physiology performed in animals anesthetized with these drugs.