Mapping the Alterations of Glutamate Using Glu-Weighted CEST MRI in a Rat Model of Fatigue

Ruili Li; Zhuozhi Dai; Di Hu; Haiyan Zeng; Zeman Fang; Zerui Zhuang; Haiyun Xu; Qingjun Huang; Yilong Cui; Handi Zhang

doi:10.3389/fneur.2020.589128

Mapping the Alterations of Glutamate Using Glu-Weighted CEST MRI in a Rat Model of Fatigue

Front Neurol. 2020 Oct 29:11:589128. doi: 10.3389/fneur.2020.589128. eCollection 2020.

Authors

Ruili Li¹, Zhuozhi Dai^{2

3}, Di Hu⁴, Haiyan Zeng^{1

5}, Zeman Fang¹, Zerui Zhuang³, Haiyun Xu^{1

6}, Qingjun Huang¹, Yilong Cui⁵, Handi Zhang¹

Affiliations

¹ Department of Psychiatry, Mental Health Center of Shantou University, Shantou, China.
² Department of Radiology, Shantou Central Hospital, Shantou, China.
³ Department of Radiology, The Second Affiliated Hospital of Shantou University Medical College, Shantou, China.
⁴ Laboratory for Biofunction Dynamic Imaging, RIkagaku KENkyusho/Institute of Physical and Chemical Research (RIKEN) Center for Systems Dynamics Research, Kobe, Japan.
⁵ Mental Health Center, Xianyue Hospital, Xiamen, China.
⁶ School of Psychiatry, Wenzhou Medical University, Wenzhou, China.

Abstract

Objective: Glutamate dysregulation may play an important role in the pathophysiology of fatigue. Glutamate weighted chemical exchange saturation transfer (Glu-weighted CEST) MRI is a recently developed technology which enables measuring glutamate in vivo with high sensitivity and spatial resolution. The purpose of this study is to map the alternations of brain glutamate in a rat model of fatigue. Methods: Rats were subjected to 10 days fatigue loading procedure (fatigue group) or reared without any fatigue loading (control group). Spontaneous activities of rats in the fatigue group were recorded from 3 days before fatigue loading to 4 days after the end of fatigue loading. Glu-weighted CEST were performed following 10-day fatigue loading. Results: Rats in the fatigue group exhibited significant reduced spontaneous activities after 10-day fatigue loading. The glutamate level in the whole brain increased significantly in the fatigue group compared to that in the control group. Further analysis of glutamate in the sub-regions of brain including the prefrontal cortex, hippocampus, and striatum revealed a trend of increment, although statistical significance was not reached. Significance: The increase of glutamate level in the brain may be a crucial process involved in the pathophysiology of fatigue.

Keywords: chronic fatigue syndrome; fatigue; glutamate; glutamate weighted chemical exchange saturation transfer (Glu-weighted CEST); spontaneous activity.