Li Yun, Li Haibo, Hou Shaowei, Meng Yu, Wang Yuanlin, Yu Jiafeng, Long Siwen, Feng Jingyu, Li Deqiang, Li Peng, Li Yize, Lu Yuechun, Xie Keliang, Yu Yonghao, Zhao Lina
Department of Anesthesiology, The Second Hospital of Tianjin Medical University, Tianjin 300211, China.
Department of Anesthesiology, Chifeng Municipal Hospital, Chifeng 024000, Inner Mongolia, China.
Phytomedicine. 2025 Nov;147:157166. doi: 10.1016/j.phymed.2025.157166. Epub 2025 Aug 12.
Delirium is a cerebral manifestation commonly seen in sepsis, known as sepsis-associated delirium (SAD), and is thought to be closely related to excitatory nervous system disorders. Metabotropic glutamate receptor 5 (mGluR5) is one of the important receptors in the central glutamatergic nervous system, which is widely involved in the regulation of synaptic transmission, synaptic plasticity and excitatory/inhibitory balance. The inhibition of mGluR5 is considered as a potential drug target for reversing excitatory nervous system disorders. However, whether blocking mGluR5 signaling can be used as a treatment for SAD is still unknown.
This study aimed to investigate the potential mechanisms of mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) in treating SAD by modulating hippocampal mGluR5 signaling and pyramidal neuron excitability.
LPS-induced sepsis mouse model and HT22 cells were established to evaluate the preventive effect of MPEP on SAD. Behavioral tests such as the buried food test (BFT), open field test (OFT) and Y-maze test, combined with cortical electroencephalogram (EEG) detection, were used to assess SAD. Magnetic resonance imaging (MRI) was used to assess changes in hippocampal Glu metabolism and perfusion. The hippocampus was extracted for assays, including ELISA for glutamate (Glu) level, RT-qPCR for mGluR5 mRNA expression, WB for mGluR5 protein expression, IF for mGluR5 intensity, and TUNEL staining for apoptosis of pyramidal cells, as well as Nissl and Golgi staining for neuronal damage. In addition, fiber-optic Ca imaging, microelectrode array (MEA), and whole-cell patch clamp in hippocampal CA1 region were used to assess changes in pyramidal neuron activity and synaptic transmission.
10 mg/kg MPEP alleviated LPS-induced delirium-like behaviors, such as a 41 % reduction in the latency to eat food in the BFT, a 97 % increase in the time spent in the central area in the OFT, and 195 % and 267 % increase in the entries into the novel arm and the duration in the novel arm in the Y-maze test, respectively. MPEP with 10 mg/kg reduced the high expression of mGluR5 and the increase in Ca activity in pyramidal neurons in the hippocampal CA1 region, repaired neuronal damage, and decreased excitatory synaptic transmission in LPS-induced sepsis mice.
This study suggests that MPEP alleviates SAD by blocking the mGluR5 signaling, thereby reducing excitotoxic damage to hippocampal CA1 pyramidal neurons. These findings support further exploration of MPEP as a candidate drug for the clinical treatment of SAD from the preclinical level.
谵妄是脓毒症中常见的一种脑部表现，称为脓毒症相关性谵妄（SAD），被认为与兴奋性神经系统紊乱密切相关。代谢型谷氨酸受体5（mGluR5）是中枢谷氨酸能神经系统中的重要受体之一，广泛参与突触传递、突触可塑性和兴奋/抑制平衡的调节。抑制mGluR5被认为是逆转兴奋性神经系统紊乱的潜在药物靶点。然而，阻断mGluR5信号通路是否可用于治疗SAD仍不清楚。
本研究旨在探讨mGluR5拮抗剂2-甲基-6-（苯乙炔基）-吡啶（MPEP）通过调节海马mGluR5信号通路和锥体神经元兴奋性来治疗SAD的潜在机制。
建立脂多糖（LPS）诱导的脓毒症小鼠模型和HT22细胞，以评估MPEP对SAD的预防作用。采用埋藏食物试验（BFT）、旷场试验（OFT）和Y迷宫试验等行为学测试，并结合皮层脑电图（EEG）检测来评估SAD。利用磁共振成像（MRI）评估海马谷氨酸（Glu）代谢和灌注的变化。提取海马进行检测，包括ELISA检测谷氨酸（Glu）水平、RT-qPCR检测mGluR5 mRNA表达、WB检测mGluR5蛋白表达、IF检测mGluR5强度、TUNEL染色检测锥体细胞凋亡，以及Nissl和Golgi染色检测神经元损伤。此外，采用海马CA1区的光纤钙成像、微电极阵列（MEA）和全细胞膜片钳技术评估锥体神经元活性和突触传递的变化。
10 mg/kg的MPEP减轻了LPS诱导的谵妄样行为，如BFT中进食潜伏期缩短41%，OFT中中央区域停留时间增加97%，Y迷宫试验中进入新臂的次数和在新臂中的停留时间分别增加195%和267%。10 mg/kg的MPEP降低了海马CA1区锥体神经元中mGluR5的高表达和钙活性的增加，修复了神经元损伤，并减少了LPS诱导的脓毒症小鼠的兴奋性突触传递。
本研究表明，MPEP通过阻断mGluR5信号通路减轻SAD，从而减少对海马CA1锥体神经元的兴奋性毒性损伤。这些发现支持从临床前水平进一步探索MPEP作为SAD临床治疗候选药物。
