Chloride Cotransporter Function in the Retina

描述(申请人提供)：这项研究项目是一项实验研究，旨在了解阳离子-氯化物共转运体在视网膜信息处理中的作用。在视网膜和中枢神经系统的其他部位，已发现两种类型的氯离子共转运体，即Na-K-2Cl(NKCC)和K-Cl(KCC)共转运体。这些氯离子共转运体调节细胞内的氯离子浓度，使KCC将氯离子从神经元排出，而NKCC则将氯离子输送到细胞内。因此，由于KCC的作用，当氯平衡电位比静息膜电位更负时，打开氯通道的神经递质GABA会使神经元超极化。相反，由于NKCC的作用，当氯平衡电位比静息膜电位更正时，GABA使神经元去极化。因此，根据视网膜神经元表达的氯离子共转运体的类型，GABA将使细胞超极化或去极化。因此，我们将结合电生理学、神经化学、细胞/分子和解剖学技术来确定氯离子共转运体在视网膜中的作用。兔眼上盖神经视网膜制备将用于研究氯离子共转运体在视网膜外部定向选择性和突触传递中的作用。具体地说，我们将确定在光适应条件下，氯转运蛋白活性是否介导双极细胞和神经节细胞的感受野周围。我们还将确定氯离子共转运体在星爆无长突细胞方向选择性光反应中的作用，星爆无长突细胞是突触前到开关方向选择性神经节细胞的中间神经元。公共卫生相关性：增加对成人视网膜中氯离子共转运体活性的了解将有助于了解人类视网膜的功能和功能障碍，并为涉及氯离子共转运体的视网膜疾病(如视网膜缺血)的药物治疗提供基础。此外，增加对氯离子转运蛋白的了解可能有助于理解和治疗癫痫和其他涉及氯离子稳态和GABA的疾病。

DESCRIPTION (provided by applicant): This research project is an experimental study that seeks to understand the role of cation-chloride cotransporters in information processing in the retina. In the retina and elsewhere in the central nervous system, two types of chloride cotransporter, the Na-K-2Cl (NKCC) and K-Cl (KCC) cotransporters, have been identified. These chloride cotransporters regulate the intracellular chloride concentration such that KCC extrudes chloride from neurons, whereas NKCC transports chloride into cells. Thus, the neurotransmitter GABA, which opens chloride channels, hyperpolarizes neurons when the chloride equilibrium potential is more negative than the resting membrane potential due to the action of KCC. In contrast, GABA depolarizes neurons when the chloride equilibrium potential is more positive than the resting membrane potential due to the action of NKCC. Thus, depending on the type of chloride cotransporter expressed by a retinal neuron, GABA will either hyperpolarize or depolarize the cell. We will therefore determine the roles of chloride cotransporters in the retina by using a combination of electrophysiological, neurochemical, cell/molecular and anatomical techniques. The rabbit eyecup neural retina preparation will be used to study the roles of chloride cotransporters in directional selectivity and in synaptic transmission in the outer retina. Specifically, we will determine whether chloride cotransporter activity mediates the receptive field surround of bipolar cells and ganglion cells under light- adapted conditions. We will also determine the roles of the chloride cotransporters in the directionally selective light responses of starburst amacrine cells, interneurons that are pre-synaptic to ON-OFF directionally selective ganglion cells. PUBLIC HEALTH RELEVANCE: Increased knowledge of chloride cotransporter activity in the adult retina will aid in the understanding of human retinal function and dysfunction, as well as provide the basis for drug therapy for retinal disorders, such as retinal ischemia, that involve the chloride cotransporters. In addition, increased knowledge of chloride cotransporters may aid in the understanding and treatment of epilepsy and other diseases that involve chloride homeostasis and GABA.