Tang Fei, Liu Hui, Zhang Xiao Jie, Zheng Hui Hui, Dai Yong Ming, Zheng Li Yun, Yang Wen Han, Du Yan Yao, Liu Jun
Department of Radiology, Second Xiangya Hospital of Central South University, Changsha, China.
MR Collaboration, Central Research Institute, United Imaging Healthcare, Shanghai, China.
Front Aging Neurosci. 2022 May 30;14:865825. doi: 10.3389/fnagi.2022.865825. eCollection 2022.
Neuromelanin-sensitive magnetic resonance imaging (NM-MRI) is a newly developed MRI technique that provides a non-invasive way to indirectly measure of dopamine (DA) function. This study aimed to determine NM concentrations in brain regions following acute methamphetamine (MA) administration using NM-MRI and to explore whether NM-MRI can be used as a biomarker of DA function in non-neurodegenerative diseases.
Baseline NM-MRI, T1-weighted and T2-weighted images were acquired from 27 rats before drug/placebo injection. The control group ( = 11) received acute placebo (Normal saline), while the experimental group ( = 16) received acute MA. NM-MRI scans were performed 5, 30, 60 and 90 min after injection. Regions of interest (ROIs), including the caudate putamen (CP), nucleus accumbens (NAc), hippocampus (HIP), substantia nigra (SN) and crus cerebri (CC), were manually drawn by an experienced radiologist. NM-MRI signal intensity in five brain regions at different time points (baseline and 5, 30, 60, and 90 min) were analyzed.
In both the control and experimental groups, at each time point (baseline and 5, 30, 60, and 90 min), the SN exhibited significantly higher NM-MRI signal intensity than the other brain regions ( < 0.05). In addition, acute MA administration resulted in a continuous upward trend in NM-MRI signal intensity in each brain region over time. However, there was no such trend over time in the control group. The NM-MRI signal intensity of SN in the experimental group was significantly higher at the 60 and 90 min compared with that in the control group ( values were 0.042 and 0.042 respectively). Within experimental group, the NM-MRI signal intensity of SN was significantly higher at the 60 and 90 min compared with that before MA administration ( values were 0.023 and 0.011 respectively). Increased amplitudes and rates of NM-MRI signal intensity were higher in the SN than in other brain regions after MA administration.
Our results indicated that NM was mainly deposited in the SN, and the conversion of DA to NM was most significant in the SN after acute MA exposure. Increased DA release induced by acute MA exposure may lead to increased accumulation of NM in multiple brain regions that can be revealed by NM-MRI. NM-MRI may serve as a powerful imaging tool that could have diverse research and clinical applications for detecting pathological changes in drug addiction and related non-neurodegenerative diseases.
神经黑色素敏感磁共振成像（NM-MRI）是一种新开发的MRI技术，它提供了一种间接测量多巴胺（DA）功能的非侵入性方法。本研究旨在使用NM-MRI确定急性给予甲基苯丙胺（MA）后大脑区域中的神经黑色素（NM）浓度，并探讨NM-MRI是否可作为非神经退行性疾病中DA功能的生物标志物。
在注射药物/安慰剂前，从27只大鼠获取基线NM-MRI、T1加权和T2加权图像。对照组（n = 11）接受急性安慰剂（生理盐水），而实验组（n = 16）接受急性MA。在注射后5、30、60和90分钟进行NM-MRI扫描。由经验丰富的放射科医生手动绘制感兴趣区域（ROI），包括尾状壳核（CP）、伏隔核（NAc）、海马（HIP）、黑质（SN）和大脑脚（CC）。分析不同时间点（基线以及5、30、60和90分钟）五个脑区的NM-MRI信号强度。
在对照组和实验组中，在每个时间点（基线以及5、30、60和90分钟），SN的NM-MRI信号强度均显著高于其他脑区（P < 0.05）。此外，急性给予MA导致每个脑区的NM-MRI信号强度随时间呈持续上升趋势。然而，对照组中未出现这种随时间变化的趋势。实验组中SN在60和90分钟时的NM-MRI信号强度显著高于对照组（P值分别为0.042和0.042）。在实验组内，SN在60和90分钟时的NM-MRI信号强度显著高于给予MA前（P值分别为0.023和0.011）。给予MA后，SN中NM-MRI信号强度的增加幅度和速率高于其他脑区。
我们的结果表明，NM主要沉积在SN中，急性MA暴露后SN中DA向NM的转化最为显著。急性MA暴露诱导的DA释放增加可能导致多个脑区中NM积累增加，这可通过NM-MRI显示。NM-MRI可能是一种强大的成像工具，在检测药物成瘾及相关非神经退行性疾病的病理变化方面可能有多种研究和临床应用。
