Cerebellar Function in Health and Disease

描述（由申请人提供）：许多神经系统疾病是发作性的。患有这些疾病的受试者在发作之间的症状相对较少。然而，他们偶尔会遭受严重的神经系统攻击，持续时间从几分钟到几小时不等。这些疾病包括偏头痛、发作性共济失调和阵发性运动障碍。这些发作通常是由情绪或身体压力等因素引发的，或者是由摄入相对无害的咖啡因和乙醇引起的。发作性2型共济失调（EA2）是一种由P/ q型钙通道突变引起的遗传性共济失调，就是这样一种疾病。在过去的资助期内，我们提供了很好的证据来支持EA2中所见的基线共济失调可能是由小脑浦肯野细胞起搏精度的丧失引起的假设。我们还能够提供一些合理的药物治疗方法来恢复起搏的精度和减轻共济失调。在这个提议中，我们试图投入我们的努力来揭示导致EA2中严重共济失调和运动障碍发作的机制。通过建立良好的EA2小鼠模型，我们希望测试所有三种触发因素（压力，咖啡因和乙醇）通过聚集到浦肯野细胞上并将其常规活动转变为高度不稳定的突发活动而引起攻击的假设。我们的工作假设是，他的转化是由去甲肾上腺素介导的，去甲肾上腺素增加了浦肯野细胞SK通道的CK2依赖性磷酸化。一旦磷酸化，SK电导降低，从而促进浦肯野细胞爆发放电。我们将使用多种技术来验证我们的工作假设，包括运动（日）功能的行为评估、急性分离神经元的单细胞记录、脑切片制备和清醒动物的体内实验。

DESCRIPTION (provided by applicant): A number of neurologic disorders are episodic. The subjects suffering from these disorders have relatively few symptoms in between episodes. Yet they sporadically suffer from severe neurologic attacks which last from minutes to hours. These disorders include migraine, episodic ataxia, and paroxysmal dyskinesia. The episodes are often triggered by factors such as emotional or physical stress, or by ingestion of relatively harmless doses of caffeine and ethanol. Episodic ataxia type 2 (EA2), a hereditary ataxia caused by mutations in the P/Q-type calcium channels, is one such disorder. During the past funding period we provided good evidence in support of the hypothesis that the baseline ataxia seen in EA2 is likely caused by the loss of precision of pacemaking in cerebellar Purkinje cells. We were also able to offer a number of rational pharmacologic therapeutic approaches to restore the precision of pacemaking and lessen ataxia. In this proposal we seek to invest our efforts in unraveling the mechanisms that contribute to episodes of severe ataxia and dyskinesia in EA2. Using well established mouse models of EA2 we wish to test the hypothesis that all three triggers (stress, caffeine and ethanol) cause attacks by converging onto Purkinje cells and transforming their regular activity to highly erratic burst firing. Our working hypothesis is that his transformation is mediated by norepinephrine which increases CK2 dependent phosphorylation of Purkinje cell SK channels. Once phosphorylated, the SK conductance is reduced thereby promoting Purkinje cell burst firing. We will test our working hypothesis using a combination of techniques including behavioral assessment of motor (dys)function, and single cell recordings in acutely dissociated neurons, the brain slice preparation, and in vivo in awake animals.