Mitochondrial reactive oxygen species act as autocrine neuromodulators in retinal ganglion cells

项目摘要/摘要 神经元不断地在细胞膜上保持离子梯度，以促进电信号传递。 线粒体产生的三磷酸腺苷需要在电活动后重新建立这些梯度 对于信息传输来说是必要的。活性氧(ROS)的产生是不可避免的 线粒体产生能量的结果。ROS与许多控制的离子通道相互作用 神经元兴奋性，但在正常情况下ROS对神经元功能的调节程度 目前还不清楚。虽然基础水平的ROS是细胞内环境的正常特征，但ROS的长期升高 是代谢失调的一部分，代谢失调似乎是包括青光眼在内的视神经疾病的关键因素。 在视网膜神经节细胞(RGC)中，由视觉场景产生的动作电位(棘波)的比率很强 根据对比度的不同，光强度的范围围绕平均值变化。视网膜对这两种情况都能适应 亮度和对比度，降低对长时间高对比度刺激的敏感度。交换机 在低对比度和高对比度之间，平均峰值速率显著增加，因此代谢需求也随之增加。 这项研究项目的主要焦点是了解ROS的变化如何调节 在正常情况下，特别是在代谢需求发生变化期间，通过基因识别的RGC 相比之下，在轮班期间。 目标1中提出的实验将详细说明RGC亚型特异性调制的初步数据 通过提高或降低内源性ROS水平的兴奋性。实验将测试ROS水平升高的影响 关于兴奋性和抑制性输入以及使用注入电流阶跃的内在兴奋性。在《目标2》中，我将使用 成对注入电流阶跃以及低方差或高方差的高斯白噪声电流注入 模拟代谢需求低或高的状态，并确定ROS对对比适应的贡献。 最后，在目标3中，我将研究ROS与电压门控相互作用的基本生物物理 在已识别的RGC亚型的有核斑片记录中测量的电导。 因此，新陈代谢、适应能力和对退化的恢复能力是神经功能的基本特征。 这些研究将进一步加深我们对调节视网膜视觉功能的过程的理解。这个目标是 与国家眼科研究所了解视网膜回路和视网膜的健康相关目标一致 发展对治疗和预防视网膜疾病至关重要的治疗方法。

Project Summary/Abstract Neurons continuously maintain ion gradients across their cell membrane in order to facilitate electrical signaling. ATP produced by the mitochondria is required to re-establish these gradients following the electrical activity necessary for information transmission. Reactive oxygen species (ROS) are produced as an inevitable consequence of energy production in the mitochondria. ROS interact with many of the ion channels that control neuronal excitability however the degree to which ROS modulate neuronal function under normal circumstances is not clear. While a basal level of ROS is a normal feature of the intracellular milieu, prolonged elevation of ROS is part of the metabolic dysregulation that appears to be a key factor in optic neuropathies, including glaucoma. In retinal ganglion cells (RGCs) the rate of action potentials (spikes) produced by a visual scene is strongly dependent on contrast, the range of light intensities varying around the mean. The retina adapts both to mean luminance and contrast and reduces sensitivity in response to prolonged high contrast stimuli. The switch between low and high contrast dramatically increases mean spike rate and consequently metabolic demand. The primary focus of this research project is to understand how changes in ROS modulate the function of genetically identified RGCs under normal conditions particularly during the shifts in metabolic demand that occur during shifts in contrast. Experiments proposed in Aim 1 will elaborate on preliminary data showing subtype specific modulation of RGC excitability by elevating or reducing endogenous ROS levels. Experiments will test effects of elevated ROS levels on excitatory and inhibitory input as well as intrinsic excitability using injected current steps. In Aim 2, I will used paired, injected current steps as well as Gaussian white noise current injection of either low or high variance to model states of low or high metabolic demand and determine the contribution of ROS to contrast adaptation. Finally in Aim 3, I will investigate the underlying biophysics of the interaction of ROS with voltage-gated conductances measured in nucleated patch recordings from identified RGC subtypes. Metabolism, adaptation, and resilience to degeneration are fundamental features of neural function therefore these studies will further our understanding of processes mediating visual function in the retina. This objective is consistent with the health-related goals of the National Eye Institute for the understanding of retinal circuits and the development of therapeutic approaches essential for the treatment and prevention of retinal disease.