静脉麻醉药对感觉刺激诱发小鼠小脑皮层神经元突触传递及可塑性的影响

It has been confirmed that γ-aminobutyric acid A (GABAA) and N-methyl-D-aspartic acid (NMDA) receptor play critical roles during the sensory information transmission and integration in cerebellar cortex, which involve in synaptic transmission and plasticity, and control the command output of Purkinje cells (PC). Moreover, the molecular mechanisms of propofol and etomidate act on anesthetic roles via activation GABAA receptor, whereas ketamine expresses an inhibitory role of NMDA receptor. The mechanisms of anesthetic actions suggest that propofol, etomidate and ketamine may act on cerebellar cortical NMDA and GABAA receptors, and modulate neuronal activity, information transmission and plasticity. However, up to now, the mechanism of intravenous anesthetics affect the sensory stimulation evoked synaptic transmission and plasticity in cerebellar cortex are unknown. Therefore, applicant will use in vivo patch-clamp and /or cell-attached recording technique accompanied with biocytin staining and neuropharmacology methods to study the effects of intravenous anesthetics on spontaneous activity and sensory stimualtion evoked synaptic transmission in cerebellar cortical PC, molecular layer interneurons (MLI) and granule cell (GC), and investigate the sensory stimulation evoked mossy fiber-granule cell synaptic plasticity in vivo in mice. We will also investigate the mechanisms of intravenous anesthetics modulate the neuronal activity, network and information tranmission in cerebellar cortex. Our study will provide reliable experiment bachground and theory evidence for finally understand the molecular mechanisms of intravenous anesthetics act on centrol nervous system.

已证实GABAA和NMDA受体在小脑皮层感觉信息传递及整合过程中起关键作用，参与突触传递及可塑性变化，控制浦肯野细胞（PC）指令输出。而异丙酚和依托咪酯麻醉作用的分子机制与激活GABAA受体有关，氯胺酮则具有拮抗NMDA受体的作用。提示异丙酚、依托咪酯及氯胺酮麻醉可能作用于小脑皮层GABAA和NMDA受体，但迄今为止静脉麻醉药对小脑皮层感觉刺激诱发突触传递及可塑性的影响机制尚不明确。因此，申请人将应用在体膜片钳/细胞贴附式技术结合生物素染色方法及神经药理学手段，在活体动物上观察静脉麻醉药的摄入对小鼠小脑皮层PC、分子层中间神经元（MLI）和颗粒细胞（GC）自发性活动、以及感觉刺激诱发突触传递及苔状纤维-颗粒细胞（MF-GC）突触可塑性的影响，探讨静脉麻醉药对小脑皮层神经元活动、神经网络以及信息传递调制的机理，并为最终阐明静脉麻醉药对中枢神经系统作用的分子机制提供可靠的实验基础与理论依据。

已证实GABAA和NMDA受体在小脑皮层感觉信息传递及整合过程中起关键作用，参与突触传递及可塑性变化，控制浦肯野细胞（PC）指令输出。而异丙酚和依托咪酯麻醉作用的分子机制与激活GABAA受体有关，氯胺酮则具有拮抗NMDA受体的作用。提示异丙酚、依托咪酯及氯胺酮麻醉可能作用于小脑皮层GABAA和NMDA受体，但迄今为止静脉麻醉药对小脑皮层感觉刺激诱发突触传递及可塑性的影响机制尚不明确。因此，申请人应用在体膜片钳/细胞贴附式技术结合生物素染色方法及神经药理学手段，在活体动物上观察了静脉麻醉药的摄入对小鼠小脑皮层PC、分子层中间神经元（MLI）和颗粒细胞（GC）自发性活动、以及感觉刺激诱发突触传递及突触可塑性的影响。.我们的研究结果显示：.（1）在在体条件下，脑表面给予丙泊酚通过活化GABAA和甘氨酸受体抑制成年小鼠小脑浦肯野细胞自发性SS放电频率。.（2）丙泊酚通过调节GABAA受体活性，导致感觉刺激诱发的分子层场电位反应GABA能成分的竞争性抑制，进一步影响小鼠小脑皮质对感觉信息的处理；.（3）丙泊酚通过活化NMDA受体显著增强小鼠面部感觉刺激诱发的颗粒细胞层场电位反应。.（4）通过阻断GABAA受体活性，依托咪酯未能增强小鼠小脑皮层平行纤维到浦肯野细胞的兴奋性输入，证实依托咪酯通过调节 GABAA受体调节小脑皮层分子层感觉信息处理。.（5）在阻断GABAA受体活性的情况下，依托咪酯通过活化小鼠小脑颗粒细胞层CB1受体，并通过PKA信号通路抑制感觉刺激诱发的苔状纤维-颗粒细胞的突触传递。.该课题的科学意义是通过探讨静脉麻醉药对小脑皮层神经元活动、神经网络以及信息传递调制的机理，为最终阐明静脉麻醉药对中枢神经系统作用的分子机制提供可靠的实验基础与理论依据。