Two-Photon Microscopy of Oxygen Consumption in the Brain

 描述（由申请人提供）： 项目摘要：在我们对健康和患病大脑在休息和代谢活化状态下的氧代谢、输送和储备的理解中，仍然存在一个关键的差距。现有的成像技术缺乏空间和时间分辨率，以评估脑组织氧合（PO 2）和O2消耗（CMRO 2）的分布与足够的细节水平，并解开他们的动态变化内微血管域。我们建议在小动物模型中开发和验证一种新的静息态CMRO 2显微成像方法，并将其推进到能够快速高空间分辨率成像CMRO 2和PO 2。这项新技术将能够以约1 Hz的速率对CMRO 2进行区域估计，并采集详细的组织PO 2图，这对于促进我们对大脑中O2输送和消耗的理解至关重要。在目标1中，我们将开发和验证基于双光子PO 2显微镜的小型啮齿动物的高分辨率静息态CMRO 2成像方法。这种新的方法将测量静息状态区域CMRO 2皮质穿透小动脉周围的组织PO 2配置文件的基础上。在目标2中，我们将通过改进多焦点、频率调制、双光子磷光寿命成像来推进新的CMRO 2成像方法，以允许在光学散射脑组织中进行实用的快速PO 2成像，并将CMRO 2测量的速度提高到100倍（接近1 Hz）。在目标3中，我们将量化生理和病理扰动期间的局部CMRO 2。我们将测试假设，“短暂的生理或病理性神经元激活的大脑影响， 缺血导致微血管区域内O2代谢和供应与缺氧之间的不匹配”--这一机制可能是中风和其他脑损伤状态中病变生长以及微血管病中观察到的进行性神经变性的基础。该技术将在脑疾病动物模型中量化脑微血管域中的代谢和氧合方面具有广泛的实用性，这将极大地促进我们对病理生理学的理解，并导致重要临床问题（如慢性脑灌注不足，中风，小血管疾病和AD痴呆）的新治疗策略。

 DESCRIPTION (provided by applicant): PROJECT ABSTRACT A critical gap remains in our understanding of oxygen metabolism, delivery, and reserve, both at rest and during metabolic activation states in healthy and diseased brain. Available imaging techniques lack spatial and temporal resolution to assess distribution of cerebral tissue oxygenation (PO2) and O2 consumption (CMRO2) with adequate level of detail, and to unravel their dynamic changes within microvascular domains. We propose to develop and validate a new microscopic imaging method of resting state CMRO2 in small animal models, and advance it to enable rapid high spatial resolution imaging of CMRO2 and PO2. The new technology will enable regional estimation of CMRO2 at a rate of ~1 Hz together with acquisition of detailed tissue PO2 maps, which is essential for advancing our understanding of O2 delivery and consumption in the brain. In Aim1 we will develop and validate high-resolution resting state CMRO2 imaging method in small rodents based on two- photon PO2 microscopy. This new method will measure resting state regional CMRO2 based on tissue PO2 profiles around cortical penetrating arterioles. In Aim 2 we will advance new CMRO2 imaging method by improving a multifocal, frequency modulated, two-photon phosphorescence lifetime imaging to allow practical rapid PO2 imaging in optically scattering brain tissue, and to improve the speed of CMRO2 measurements up to 100-fold (approaching 1 Hz). In Aim 3 we will quantify regional CMRO2 during physiological and pathological perturbations. We will test the hypothesis that "transient physiological or pathological neuronal activation in a brain affected by ischemia leads to a mismatch between O2 metabolism and supply and hypoxia within microvascular domains" - a mechanism that may underlie lesion growth in stroke and other brain injury states as well as progressive neurodegeneration observed in microvasculopathies. This technology will have broad utility in quantifying metabolism and oxygenation in cerebral microvascular domains in animal models of brain disorders that will dramatically advance our understanding of pathophysiology and lead to novel treatment strategies in important clinical problems such as chronic cerebral hypoperfusion, stroke, small vessel disease, and AD dementia.