乙醇对感觉刺激诱发小鼠小脑颗粒细胞反应的影响机制

Mechanisms of ethanol affects sensory stimulus-evoked response in cerebelalr granule cell in vivo in mice

目的探讨乙醇对小脑颗粒细胞感觉信息传递的影响,揭示急性酒中毒对小脑皮质感觉信息传递与整合影响的部分机制。方法 ICR小鼠（6~8周龄）经腹腔注射乌拉坦（1.3 g/kg体重.）麻醉后,在小脑Crus II相应部位行直径为1~1.5 mm的开颅术,除去硬脑膜,脑表面暴露部位持续灌流人工脑脊液（ACSF）;三叉神经感觉刺激选用吹风刺激同侧触须垫,电生理记录选用GC场电位记录,通过膜片钳放大器及数据采集软件记录感觉刺激诱发GC场电位变化;电生理实验数据分析采用Clampfit 10.1软件,采用SPSS软件进行数据统计学分析。结果（1）吹风刺激（60 ms,50~60 psi）小鼠触须垫,可诱发小脑Crus II区颗粒细胞高保真反应。（2）小脑表面灌流乙醇对诱发反应的潜伏期没有明显影响,但可逆性地抑制颗粒细胞的感觉刺激诱发反应。（3）乙醇对小脑颗粒细胞的感觉刺激诱发反应的抑制作用有浓度依存性,最小抑制浓度为0.5 mmol/L,最大抑制浓度300 mmol/L。（4）高浓度乙醇（500 mmol/L）明显降低P1振幅中值（half-width）、振幅下面积（area）、P1上升参数（rise tau）和衰减参数（decay tau）,表明高浓度乙醇严重影响递质传递与信息传导。（5）阻断GABAA受体活性增强P1振幅,同时完全阻断乙醇对GC感觉刺激诱发反应的抑制作用,表明乙醇通过增强GABAA受体活性来抑制GC感觉刺激诱发反应。结论乙醇通过增强GABAA受体活性对小脑颗粒细胞感觉刺激诱发反应产生明显的抑制作用,表明乙醇抑制小脑颗粒细胞对感觉信息的传递,提示急性酒中毒对小脑运动调节功能的损害可能与乙醇抑制小脑皮质感觉信息传递有关。

Objective The mechanisms of the effects of ethanol on the sensory information transferred by cerebellar GCs,and reveal a partial mechanisms of sensory information integration and transmission in cerebellar cortex. Methods After ICR mice were anesthetized by intraperitoneal injection of urethane（ 1. 3 g / kg body weight i. p.）,a 1 ~ 1. 5 mm craniotomy were drilled to expose the cerebellar surface corresponding to cerebellar cortex Crus II. The dura were removed,and the cerebellar surface was constantly superfused with oxygenated artificial cerebrospinal fluid（ ACSF）. Sensory stimuli were performed by air-puff stimulation（ 60 ms,50 ~ 60 psi） of ipsilateral whisker pad. Field potential recording were employed to record the sensory stimuli evoked responses in cerebellar GC. Electrophysiological data were analyzed using Clampfit 10.1 software. Differences between the mean values recorded under control and test conditions were evaluated by Student＇s paired t-test using SPSS software. Results（ 1） Air-puff stimulation of ipsilateral whisker- pad evoked high fidelity responses in GCs in cerebellar Crus II.（ 2） Cerebellar surface perfusion of ethanol did not change the latency of the evoked responses,but reversible inhibited the sensory stimulation evoked responses in GCs.（ 3） The ethanol- induced inhibition of the sensory stimulation evoked responses was concentration dependent,the minimal concentration is 0. 5 mmol / L,the maximal inhibitory concentration is 300 mmol / L that induced a decrease in the normalized amplitude of P1.（ 4） High concentration of ethanol significantly induced decreases in half-width,area,rise tau and decay tau of P1.（ 5） Blockade of GABAA receptor activity induced an increase in amplitude of P1,and abolished the ethanol induced inhibition in the sensory stimulation-evoked responses of GCs,indicated that ethanol induced inhibition in GC sensory stimulation-evoked responses of cerebellar Cs via the enhancement of GABAA receptors activity. Conclusions Ethanol inhibited the sensory-stimulation evoked responses in cerebellar GCs through the enhancement of GABA receptor activation,indicated that ethanol inhibited the cerebellar GCs to transfer the sensory information. These results suggested that the impairment of cerebellar motor coordination by acute alcohol intoxication could be related with ethanol induced inhibition in the cerebellar cortical sensory information transmission.