Epilepsy and dendritic excitability

描述（由申请人提供）：癫痫是一种神经元兴奋性异常的疾病，但这种过度兴奋的原因在很大程度上仍然未知。我们的理解神经元兴奋性的内在决定因素有显着改善，近年来由于技术的进步，允许神经元树突的电生理研究，如CA1海马和新皮质锥体神经元。该建议调查颞叶癫痫与主要定位于树突的电压门控通道（h通道或Ih）的生物物理特性改变相关的可能性。先前的研究发现，海马锥体神经元中的Ih可以通过单次长时间癫痫发作而改变，并且Ih是抗惊厥作用的靶点。我们建议研究海马锥体神经元树突中的Ih，以确定其性质是否在慢性癫痫动物模型中发生改变。由于PI和其他人先前的工作表明，树突状Ih降低整体锥体神经元兴奋性，我们的中心假设是，Ih可能在癫痫动物锥体神经元树突中下调，产生神经元超兴奋性。我们将调查Ih的变化后，诱导毛果芸香碱，无论是出现之前的复发性癫痫发作（潜伏期）和慢性癫痫建立后，以评估改变4在癫痫发生的作用。建议的研究涉及全细胞和细胞贴附膜片钳电生理学的索马和树突的CA 1海马锥体神经元制备使用脑切片技术，以及HCN的表达使用Western印迹测量。具体来说，我们将回答以下问题：1）在正常条件下，锥体神经元树突中的Ih是如何调制的？2)癫痫动物锥体神经元树突的Ih特性是否改变？3)慢性癫痫患者树突状细胞Ih是否有差异调节？这些研究可能为癫痫部分由神经元内在兴奋性变化引起的假说提供进一步的证据，并可能提出新的靶点，如h通道或其调节剂，用于治疗癫痫。

DESCRIPTION (provided by applicant): Epilepsy is a disease of abnormal neuronal excitability, but the causes of this hyperexcitability remain largely unknown. Our understanding of the intrinsic determinants of neuronal excitability has significantly improved in recent years due to technical advances which allow electrophysiological study of neuronal dendrites, such as those of CA1 hippocampal and neocortical pyramidal neurons. This proposal investigates the possibility that temporal lobe epilepsy is associated with altered biophysical properties of a voltage-gated channel which is primarily localized to dendrites, the h-channel or Ih. Prior studies have found that Ih in hippocampal pyramidal neurons can be altered by a single prolonged seizure, and that Ih is a target of anticonvulsant action. We propose studying Ih in hippocampal pyramidal neuron dendrites to determine if its properties are altered in an animal model of chronic epilepsy. Because prior work by the PI and others has shown that dendritic Ih reduces overall pyramidal neuron excitability, our central hypothesis will be that Ih may be downregulated in the dendrites of pyramidal neurons in epileptic animals, producing neuronal hyperexcitability. We will investigate changes in Ih following induction by pilocarpine, both before the appearance of recurrent seizures (the latent period) and after chronic epilepsy is established in order to assess the role of altered 4 in epileptogenesis. The studies proposed involve whole-cell and cell-attached patch clamp electrophysiology in the soma and dendrites of CA1 hippocampal pyramidal neurons prepared using brain slice techniques, as well as measurement of HCN expression using Western blots. Specifically, we will answer the following questions: 1) How is Ih modulated under normal conditions in pyramidal neuron dendrites? 2) Are Ih properties altered in pyramidal neuron dendrites from epileptic animals? 3) Is dendritic Ih differentially modulated in chronic epilepsy? These studies may provide further evidence for the hypothesis that epilepsy results in part from changes in the intrinsic excitability of neurons, and may suggest novel targets, such as the h-channel or its modulators, in the treatment of epilepsy.