NMR Research Centre, Institute of Nuclear Medicine and Allied Sciences (INMAS), Delhi.
Int J Radiat Biol. 2013 Mar;89(3):212-8. doi: 10.3109/09553002.2013.734944. Epub 2012 Nov 8.
Abstract Purpose: In the classical description of acute radiation syndrome, the role of central nervous system (CNS) is underestimated. It is now well recognised that ionising radiation-induced oxidative stress may bring about functional changes in the brain. In this study, we prospectively evaluated metabolic changes in the brain after whole body irradiation in mice using in vivo proton ((1)H) nuclear magnetic resonance spectroscopy (MRS).
Young adult mice were exposed to whole body irradiation of 8 Gy and controls were sham irradiated. In vivo (1)H MRS from cortex-hippocampus and hypothalamic-thalamic region of brain at different time points, i.e., as early as 6 hours, day 1, 2, 3, 5 and 10 post irradiation was carried out at 7 Tesla animal magnetic resonance imaging system. Brain metabolites were measured and quantitative analysis of detectable metabolites was performed by linear combination of model (LCModel).
Significant reduction in myoinositol (p = 0.03) and taurine (p = 0.02) ratios were observed in cortex-hippocampus region as early as day 2 post irradiation compared to controls. These metabolic alterations remained sustained over day 10 post irradiation.
The results of this preliminary study suggest that the alteration/reduction in the mI and Tau concentration may be associated with physiological perturbations in astrocytes or radiation induced neuro-inflammatory response triggered in microglial cell.
在急性放射综合征的经典描述中，中枢神经系统（CNS）的作用被低估了。现在人们已经认识到，电离辐射引起的氧化应激可能会导致大脑的功能变化。在这项研究中，我们使用活体质子（1H）磁共振波谱（MRS）前瞻性地评估了全身照射后小鼠大脑的代谢变化。
年轻成年小鼠接受 8 Gy 的全身照射，对照组进行假照射。在 7T 动物磁共振成像系统上，在不同时间点（即照射后 6 小时、第 1 天、第 2 天、第 3 天、第 5 天和第 10 天）对大脑皮质-海马区和下丘脑-丘脑区进行活体 1H MRS。通过线性组合模型（LCModel）测量脑代谢物，并对可检测代谢物进行定量分析。
与对照组相比，照射后第 2 天，皮质-海马区的肌醇（p=0.03）和牛磺酸（p=0.02）比值显著降低。这些代谢变化在照射后第 10 天仍持续存在。
这项初步研究的结果表明，mI 和 Tau 浓度的改变/降低可能与星形胶质细胞的生理紊乱或辐射诱导的小胶质细胞触发的神经炎症反应有关。
