Giovacchini Giampiero, Chang Michael C J, Channing Michael A, Toczek Maria, Mason Alicja, Bokde Arun L W, Connolly Catherine, Vuong Bik-Kee, Ma Ying, Der Margaret G, Doudet Doris J, Herscovitch Peter, Eckelman William C, Rapoport Stanley I, Carson Richard E
Brain Physiology and Metabolism Section, National Institute on Aging, Bethesda, Maryland, U.S.A.
J Cereb Blood Flow Metab. 2002 Dec;22(12):1453-62. doi: 10.1097/01.WCB.0000033209.60867.7A.
Arachidonic acid (AA) is an important second messenger involved in signal transduction mediated by phospholipase A2. The goal of this study was to establish an in vivo quantitative method to examine the role of AA in this signaling process in the human brain. A simple irreversible uptake model was derived from rat studies and modified for positron emission tomography (PET) to quantify the incorporation rate K* of [11C]AA into brain. Dynamic 60-minute three-dimensional scans and arterial input functions were acquired in 8 young healthy adults studied at rest. Brain radioactivity was corrected for uptake of the metabolite [11C]CO2. K* and cerebral blood volume (Vb) were estimated pixel-by-pixel and were calculated in regions of interest. K* equaled 5.6+/-1.2 and 2.6+/-0.5 microL x min(-1) x mL(-1) in gray and white matter, respectively. K* and Vb values were found to be unchanged with data analysis periods from 20 to 60 minutes. Thus, PET can be used to obtain quantitative images of the incorporation rate K* of [11C]AA in the human brain. As brain incorporation of labeled AA has been shown in awake rats to be increased by pharmacological activation associated with phospholipase A2-signaling, PET and [11C]AA may be useful to measure signal transduction in the human brain.
花生四烯酸（AA）是参与磷脂酶A2介导的信号转导的重要第二信使。本研究的目的是建立一种体内定量方法，以研究AA在人脑中该信号传导过程中的作用。一个简单的不可逆摄取模型源自大鼠研究，并针对正电子发射断层扫描（PET）进行了修改，以量化[11C]AA进入脑内的掺入率K*。对8名静息状态下的年轻健康成年人进行了60分钟的动态三维扫描和动脉输入函数采集。对脑放射性进行了代谢物[11C]CO2摄取的校正。逐像素估计K和脑血容量（Vb），并在感兴趣区域进行计算。灰质和白质中的K分别为5.6±1.2和2.6±0.5微升·分钟-1·毫升-1。发现K和Vb值在20至60分钟的数据分析期内保持不变。因此，PET可用于获取人脑中[11C]AA掺入率K的定量图像。由于在清醒大鼠中已表明，与磷脂酶A2信号传导相关的药理学激活可增加标记AA在脑中的掺入，PET和[11C]AA可能有助于测量人脑中的信号转导。
