肾上腺素能受体在小鼠小脑皮层感觉信息处理和运动调节中的作用

The outside information transferred into cerebellar cortex and integrated by cortical neurons. The commands are output by cerebellar Purkinje cells (PCs) which are involved in motor regulation. Noradrenergic fibers and adrenergic receptors (AR) are widely distributed in molecular layer, PC layer and granule cell layer of cerebellar cortex. We previously found that application of norepinephrine (NE) significantly inhibited the spontaneous simple spike firing rate, while our preliminary experimental results showed that application NE blocked the tactile stimulation-evoked field potential responses in cerebellar molecular layer and granule cell layer, suggesting that NE and AR are involved in the cerebellar sensory information processing and motor regulation. However, the effective mechanisms of NE and AR are currently unclear. Therefore, applicant will use in vivo whole-cell patch clamp recording, biocytin staining and pharmacology methods to study the pharmacological mechanisms of NE and AR blocker affect the spontaneous activity and the sensory stimulation-evoked synaptic currents of cerebellar cortical PCs, MLIs, GCs and Golgi cells in urethane-anesthetized mice. To clarify the role of ARs during the sensory information processed in cerebellar cortex. Furthermore, we will investigate the effect of NE and AR blocker on locomotion behavior of free moving mice using cerebellar surface microinjection methods. We aim to understand the functional mechanism of NE and AR during the cerebellar regulation of locomotion behavior. Our results will provide partly experimental evidences for revealing the pathogenesis of cerebellar motor disorders.

传入小脑皮层的外部信息经神经网络整合后，由浦肯野细胞（PC）发出指令，参与运动调节。去甲肾上腺素（NE）能纤维和肾上腺素能受体(AR)广泛分布于小脑皮质分子层、PC层和颗粒细胞（GC）层，前期研究发现NE可抑制小脑皮层PC自发性简单峰电位放电频率，而预实验结果表明NE可阻断感觉刺激引起的小脑分子层和GC层的场电位反应，提示NE和AR参与小脑感觉信息处理与运动调节,但迄今，其影响机制还不清楚。申请人拟应用在体膜片钳、生物素染色和药理学手段，研究NE和AR阻断剂对麻醉小鼠小脑皮层PC、分子层中间神经元（MLI）、GC和Golgi细胞自发性活动及感觉刺激诱发突触电流的影响及药理学机制，明确AR在小脑皮层感觉信息处理中的作用；通过脑表面微量给药研究NE及AR阻断剂对自由活动小鼠行走行为的影响，明确NE和AR在小脑运动调节中的作用机制，研究成果将为揭示小脑运动障碍性疾病的发病机制提供一定的实验依据。

去甲肾上腺素（NE）是一种重要的神经递质，广泛作用于中枢神经系统。小脑中的内源性NE是由蓝斑核（LC）的NA能神经元释放的，而释放到小脑皮层的NE通过其肾上腺素能受体（AR）调节小脑皮层神经环路的突触传递及信息整合，并参与小脑的运动调节和运动学习功能。本研究应用在体和离体电生理学和神经药理学手段，研究了NE和AR在麻醉小鼠小脑皮层浦肯野细胞（PC）、分子层中间神经元（MLI）、颗粒细胞（GC）和Golgi细胞自发性活动及感觉刺激诱发突触电流中的影响及药理学机制，明确了阻断GABA能抑制性网络后,NE能够通过活化α2-AR而不是β-AR减弱爬行纤维（CF）-PC突触传递，抑制复杂峰电位（CS）活动，减小后超级化电位（AHP）从而增强了PC的SS放电频率；在小鼠小脑中NE通过同时活化α2a-和α2b-AR两种亚型来抑制AC-cAMP-PKA通路从而调节神经递质的释放，进而调节小脑皮层的CF-PC突触传递；小脑内的LC-NE 能投射纤维能够通过活化α2-AR 来抑制感觉刺激诱发的谷氨酸能和GABA 能反应，从而调节局部小脑环路中感觉信息的整合与传递；NE通过活化α2-AR受体抑制感觉刺激诱发的苔藓纤维（MF）-GC突触传递，并伴有双脉冲比率升高，提示去甲肾上腺素能输入通过突触前α2受体下调谷氨酸释放，压制感觉刺激诱发的MF-GC兴奋性突触传递; 20赫兹的面部感觉刺激可以诱发MF-GC LTP， NE可通过活化突触前α2-AR，介导面部感觉刺激诱发PKA信号通路依赖的MF-GC LTD。研究成果将为揭示小脑运动障碍性疾病的发病机制提供一定的实验依据。