Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong.
Alzheimer's Disease Research Network, The University of Hong Kong, Hong Kong.
Eur J Neurosci. 2021 Aug;54(4):5310-5326. doi: 10.1111/ejn.15399. Epub 2021 Aug 2.
The glutamatergic cycle is essential in modulating memory processing by the hippocampal circuitry. Our combined proton magnetic resonance spectroscopy ( H-MRS) and task-based functional magnetic resonance imaging (fMRI) study (using face-name paired-associates encoding and retrieval task) of a cognitively normal cohort of 67 healthy adults (18 ApoE4 carriers and 49 non-ApoE4 carriers) found altered patterns of relationships between glutamatergic-modulated synaptic signalling and neuronal activity or functional hyperaemia in the ApoE4 isoforms. Our study highlighted the asymmetric left-right hippocampal glutamatergic system in modulating neuronal activities in ApoE4 carriers versus non-carriers. Such brain differentiation might be developmental cognitive advantages or compensatory due to impaired synaptic integrity and plasticity in ApoE4 carriers. As there was no difference in myoinositol levels measured by MRS between the ApoE4 and non-ApoE4 subgroups, the mechanism is unlikely to be a response to neuroinflammation.
谷氨酸能循环对于调节海马回路的记忆处理至关重要。我们对 67 名认知正常的成年人（18 名载脂蛋白 E4 携带者和 49 名非载脂蛋白 E4 携带者）进行了质子磁共振波谱（H-MRS）和基于任务的功能磁共振成像（fMRI）联合研究（使用面孔-名字配对联想物编码和检索任务），发现载脂蛋白 E4 同种型中谷氨酸能调节的突触信号与神经元活动或功能充血之间的关系模式发生了改变。我们的研究强调了载脂蛋白 E4 携带者与非携带者的左侧和右侧海马谷氨酸能系统在调节神经元活动方面的不对称性。这种大脑分化可能是由于载脂蛋白 E4 携带者的突触完整性和可塑性受损而导致的发育认知优势或代偿。由于 MRS 测量的肌醇水平在载脂蛋白 E4 亚组和非载脂蛋白 E4 亚组之间没有差异，因此该机制不太可能是对神经炎症的反应。
