Imaging the effect of the circadian light-dark cycle on the glymphatic system in awake rats
Imaging the effect of the circadian light-dark cycle on the glymphatic system in awake rats
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DOI：
10.1073/pnas.1914017117
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发表时间：
2020-01-07
影响因子：
11.1
通讯作者：
Ferris, Craig F.
中科院分区：
文献类型：
--
作者：
Cai, Xuezhu;Qiao, Ju;Ferris, Craig F.
类淋巴系统的功能是清除大脑中潜在有害的代谢物和蛋白质。对完全清醒的大鼠进行动态对比增强 MRI，以追踪明暗循环中脑室内造影剂的重新分布及其与特定脑区域的睡眠-觉醒周期、血流量和脑温度的假设关系。参与昼夜节律和睡眠-觉醒节律的大脑区域在大鼠的光相或不活动和睡眠时间显示出造影剂的重新分布最低。造影剂的大脑整体重新分布是不均匀的。沿大脑背侧的重新分布最高，中脑/脑桥和沿大脑腹侧表面的重新分布最低。造影剂的这种异质重新分布与文献中报道的清醒动物脑温度的梯度和区域变化平行。三维定量超短回波时间对比增强成像用于重建大鼠大脑中的小、中、大动脉和静脉，并揭示与该大血管系统重叠的最低再分布区域。这项研究提出了关于光暗循环、大脑温度和血流对类淋巴系统功能影响的新问题和理论思考。
The glymphatic system functions in the removal of potentially harmful metabolites and proteins from the brain. Dynamic, contrast-enhanced MRI was used in fully awake rats to follow the redistribution of intraventricular contrast agent entrained to the light-dark cycle and its hypothetical relationship to the sleep-waking cycle, blood flow, and brain temperature in specific brain areas. Brain areas involved in circadian timing and sleep-wake rhythms showed the lowest redistribution of contrast agent during the light phase or time of inactivity and sleep in rats. Global brain redistribution of contrast agent was heterogeneous. The redistribution was highest along the dorsal cerebrum and lowest in the midbrain/pons and along the ventral surface of the brain. This heterogeneous redistribution of contrast agent paralleled the gradients and regional variations in brain temperatures reported in the literature for awake animals. Three-dimensional quantitative ultrashort time-to-echo contrast-enhanced imaging was used to reconstruct small, medium, and large arteries and veins in the rat brain and revealed areas of lowest redistribution overlapped with this macrovasculature. This study raises new questions and theoretical considerations of the impact of the light-dark cycle, brain temperature, and blood flow on the function of the glymphatic system.