Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD, USA.
Advanced Magnetic Resonance Imaging Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
J Cereb Blood Flow Metab. 2023 Jan;43(1):59-71. doi: 10.1177/0271678X221121873. Epub 2022 Sep 7.
During sleep, reduced brain energy demands provide an opportunity for biosynthetic processes like protein synthesis. Sleep is required for some forms of memory consolidation which requires protein synthesis. We measured regional cerebral protein synthesis rates (rCPS) in human subjects to ascertain how rCPS is affected during sleep. Subjects underwent three consecutive L-[1-C]leucine PET scans with simultaneous polysomnography: 1. rested awake, 2. sleep-deprived awake, 3. sleep. Measured rCPS were similar across the three conditions. Variations in sleep stage times during sleep scans were used to estimate rCPS in sleep stages under the assumption that measured rCPS is the weighted sum of rCPS in each stage, with weights reflecting time and availability of [C]leucine in that stage. During sleep scans, subjects spent most of the time in N2, N3, and awake and very little time in N1 and REM; rCPS in N1 and REM could not be reliably estimated. When stages N1 and N2 were combined [N1,N2], estimates of rCPS were more robust. In selective regions, estimated rCPS were statistically significantly higher (30-39%) in [N1,N2] compared with N3; estimated rCPS in N3 were similar to values measured in sleep-deprived awake scans. Results indicate increased rates of protein synthesis linked to [N1,N2] sleep.
在睡眠期间，大脑能量需求降低为蛋白质合成等生物合成过程提供了机会。一些形式的记忆巩固需要蛋白质合成，而睡眠是必需的。我们测量了人类受试者的局部脑蛋白合成率 (rCPS)，以确定 rCPS 在睡眠期间是如何受到影响的。受试者接受了连续三次的 L-[1-C]亮氨酸 PET 扫描，同时进行多导睡眠图监测：1. 清醒休息，2. 清醒剥夺，3. 睡眠。在这三种情况下，测量的 rCPS 相似。在睡眠扫描期间，根据测量的 rCPS 是每个阶段 rCPS 的加权和的假设，利用睡眠阶段的时间变化来估计睡眠阶段中的 rCPS，权重反映了该阶段中 [C]亮氨酸的时间和可用性。在睡眠扫描期间，受试者大部分时间处于 N2、N3 和清醒状态，很少时间处于 N1 和 REM 状态；无法可靠估计 N1 和 REM 中的 rCPS。当将 N1 和 N2 合并为 [N1,N2] 时，rCPS 的估计更为稳健。在选择性区域中，与 N3 相比，[N1,N2] 中的估计 rCPS 显著更高（30-39%）；N3 中的估计 rCPS 与清醒剥夺扫描中测量的值相似。结果表明，与 N1 和 N2 睡眠相关的蛋白质合成率增加。
