Pericyte function in anesthetic-induced vasodilation and developmental neurotoxicity

项目摘要 越来越多的证据表明，在很小的时候反复接触麻醉药物， 脑细胞凋亡以及持久的行为和认知障碍。这背后的机制 麻醉诱导的发育神经毒性仍不清楚。众所周知，大脑有一个 特别高的能量需求，其功能在没有血液流动的情况下迅速中断。成人 在全身麻醉期间，通过血管改变血管直径， 壁细胞，如周细胞。然而，这种机制在未成熟的大脑中可能没有完全发育。在 支持，我们的初步数据表明，脑小动脉扩张的反应，吸入麻醉剂，与 使用体内成像，在成年小鼠脑中显著的扩张幅度，但在幼年小鼠脑中不显著 脑血管的一部分此外，我们发现血管周细胞是双重的， 在婴儿大脑中含量少于成人大脑。基于这些发现，我们假设缺乏收缩性 婴儿脑中对麻醉的周细胞和血管舒张反应导致脑血流不足， 这可能导致氧气和营养供应的严重代谢不足，最终导致脑细胞 死亡，是一种长久的延续。在本申请中，我们将通过结合体内 脑血管直径、流速和周细胞活性的双光子成像，区域/细胞类型特异性 光遗传学调节和细胞凋亡的免疫组织化学分析。具体而言，在目标1中，我们将 描述婴儿、青少年和年轻成人大脑皮层中挥发性麻醉剂诱发的血管舒张 小鼠我们将检验吸入麻醉剂的血管舒张反应是年龄依赖性的假设， 发育中的脑中血管舒张不足导致麻醉诱导的大量细胞凋亡。在 目的2：探讨新皮质周细胞在挥发性神经递质引起的年龄相关性血管舒张反应中的作用。 通过结合体内钙成像与光遗传学调节，我们的研究计划 将确定周细胞介导的血管舒张的缺陷作为麻醉诱导的新机制， 发育神经毒性，并表明靶向周细胞功能以保持脑血流可能 在接受全身麻醉的婴儿中提供神经保护。

Project Summary Mounting evidence suggests that repeated exposure to anesthetic drugs at a very young age causes widespread brain cell apoptosis and long-lasting behavioral and cognitive impairments. The mechanisms underlying this anesthesia-induced developmental neurotoxicity remain unclear. It is well known that the brain has an exceptionally high energy demand, and its function is rapidly disrupted in the absence of blood flow. The adult brain can maintain adequate perfusion during general anesthesia by altering vessel diameter through vascular mural cells, such as pericytes. However, this mechanism may not be fully developed in the immature brain. In support, our preliminary data suggest that cerebral arterioles dilate in response to inhaled anesthetics, with the magnitude of dilation pronounced in adult brains but insignificant in the brains of infant mice, using in vivo imaging of cerebral vasculature through a cranial window. Moreover, we have found that vascular pericytes are two-fold less abundant in infant than adult brains. Based on these findings, we hypothesize that the lack of contractile pericytes and vasodilatory responses to anesthesia in the infant brain causes a deficiency in cerebral blood flow, which may lead to a critical metabolic shortage of oxygen and nutrient supply that ultimately causes brain cell death when lasting for a prolonged duration. In this application, we will test this hypothesis by combining in vivo two-photon imaging of cerebral vessel diameter, flow velocity, and pericyte activity, region/cell-type-specific optogenetic modulation, and immunohistochemical analysis of cell apoptosis. Specifically, in Aim 1, we will characterize volatile anesthetic-evoked vasodilation in the cerebral cortex of infant, juvenile, and young adult mice. We will test the hypothesis that the vasodilatory response to inhaled anesthetics is age-dependent and inadequate vasodilation in the developing brain contributes to anesthesia-induced extensive cell apoptosis. In Aim 2, we will investigate the roles of neocortical pericytes in age-related vasodilatory responses to volatile anesthetics by combining in vivo calcium imaging with optogenetic modulation. Together, our proposed research will identify the deficiency of pericyte-mediated vasodilation as a novel mechanism of anesthesia-induced developmental neurotoxicity and suggest that targeting pericyte function to preserve cerebral blood flow may confer neuroprotection in infants undergoing general anesthesia.