Calcium-activated potassium currents in cerebellar Purkinje neurons

描述(申请人提供)：浦肯野神经元，小脑皮质的主要投射神经元，在没有突触输入的情况下发出高频动作电位。电压门控性钙通道(Ca)和钙激活钾通道(Kca)参与了这种自发活动的规律性。CA通道突变可引起许多遗传性疾病，包括发作性和脊髓小脑性共济失调，以及家族性偏瘫偏头痛。因此，研究钙和KCA通道生理学有可能增加我们对几种不同疾病状态下的病理学的理解。我们最近的工作表明，在自发放电过程中，浦肯野细胞钙电流的幅度非常稳定。这一特征将它们与大脑中的许多神经元区分开来，在大脑中，持续的高频活动导致钙电流既促进又失活，导致在动作电位期间进入细胞的钙含量发生显著变化。重要的是，浦肯野细胞钙电流具有调制能力，但易化和失活是平衡的。在我们提出的实验中，我们将研究钙内流的两个下游目标，大(BK)和小(SK)电导KCA通道，如何对高频刺激做出反应。我们将从分离的小鼠浦肯野神经元中制作全细胞电压钳记录，并测试BK和SK电流是否过滤或放大钙电流的微小变化。接下来，我们将测量这些电流在被细胞自身的动作电位波形激活时的幅度和动力学。最后，我们将检查瘦小鼠的SK电流，它有一个突变的钙通道，是共济失调的。综上所述，这些数据将帮助我们了解钙信号如何塑造浦肯野细胞的正常活动，进而了解干扰是如何导致疾病的。) 公共卫生相关性：该项目研究了小脑浦肯野细胞电活动的细胞机制，小脑浦肯野细胞是大脑中对运动协调至关重要的区域。基因突变会导致这些神经元行为异常，这被认为会导致多种形式的共济失调。我们的目标是了解浦肯野神经元的电活动是如何调节的，这有望为小脑疾病的治疗提供洞察力。)

DESCRIPTION (provided by applicant): Abstract Purkinje neurons, the principal projection neurons of the cerebellar cortex, fire high frequency action potentials in the absence of synaptic input. Voltage-gated calcium (Ca) and calcium-activated potassium (KCa) channels contribute to the regularity of this spontaneous activity. Ca channel mutations can cause a number of genetic disorders, including both episodic and spinocerebellar ataxias, as well as familial hemiplegic migraine. Thus, studying Ca and KCa channel physiology has the potential to increase our understanding of the pathology underlying several different disease states. Our recent work has shown that during spontaneous firing, Purkinje cell Ca currents are remarkably stable in amplitude. This feature distinguishes them from many neurons throughout the brain, in which sustained high-frequency activity causes Ca currents to both facilitate and inactivate, resulting in significant changes in the amount of Ca that enters the cell during an action potential. Importantly, Purkinje cell Ca currents have the capacity for modulation, but facilitation and inactivation are balanced. In our proposed experiments, we will examine how two downstream targets of Ca influx, the big (BK) and small (SK) conductance KCa channels, respond to high-frequency stimulation. We will make whole cell voltage clamp recordings from dissociated mouse Purkinje neurons and test whether BK and SK currents filter or amplify the small changes in the Ca currents. Next, we will measure the amplitude and kinetics of these currents when activated by the cells' own action potential waveform. Finally, we will examine SK currents in the leaner mouse, which has a mutant Ca channels and is ataxic. Together, these data will help us to understand how Ca signaling shapes the normal activity of Purkinje cells, and by extension, how disruptions lead to disease. ) PUBLIC HEALTH RELEVANCE: This project examines the cellular mechanisms underlying electrical activity in Purkinje cells of the cerebellum, a region of the brain important for motor coordination. Genetic mutations can cause these neurons to behave abnormally, which is thought to cause multiple forms of ataxia. Our goal is to understand how the electrical activity in Purkinje neurons is regulated, which promises to provide insight into therapeutic treatments for cerebellar disorders.)