Li Ke-Xin, Lu Meng, Cui Meng-Xu, Wang Xiao-Ming, Zheng Yang
Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, China.
Neural Regen Res. 2023 Oct;18(10):2285-2290. doi: 10.4103/1673-5374.369124.
Maintaining glutamate homeostasis after hypoxic ischemia is important for synaptic function and neural cell activity, and regulation of glutamate transport between astrocyte and neuron is one of the important modalities for reducing glutamate accumulation. However, further research is needed to investigate the dynamic changes in and molecular mechanisms of glutamate transport and the effects of glutamate transport on synapses. The aim of this study was to investigate the regulatory mechanisms underlying Notch pathway mediation of glutamate transport and synaptic plasticity. In this study, Yorkshire neonatal pigs (male, age 3 days, weight 1.0-1.5 kg, n = 48) were randomly divided into control (sham surgery group) and five hypoxic ischemia subgroups, according to different recovery time, which were then further subdivided into subgroups treated with dimethyl sulfoxide or a Notch pathway inhibitor (N-[N-(3, 5-difluorophenacetyl-l-alanyl)]-S-phenylglycine t-butyl ester). Once the model was established, immunohistochemistry, immunofluorescence staining, and western blot analyses of Notch pathway-related proteins, synaptophysin, and glutamate transporter were performed. Moreover, synapse microstructure was observed by transmission electron microscopy. At the early stage (6-12 hours after hypoxic ischemia) of hypoxic ischemic injury, expression of glutamate transporter excitatory amino acid transporter-2 and synaptophysin was downregulated, the number of synaptic vesicles was reduced, and synaptic swelling was observed; at 12-24 hours after hypoxic ischemia, the Notch pathway was activated, excitatory amino acid transporter-2 and synaptophysin expression was increased, and the number of synaptic vesicles was slightly increased. Excitatory amino acid transporter-2 and synaptophysin expression decreased after treatment with the Notch pathway inhibitor. This suggests that glutamate transport in astrocytes-neurons after hypoxic ischemic injury is regulated by the Notch pathway and affects vesicle release and synaptic plasticity through the expression of synaptophysin.
缺氧缺血后维持谷氨酸稳态对突触功能和神经细胞活性很重要，而调节星形胶质细胞和神经元之间的谷氨酸转运是减少谷氨酸积累的重要方式之一。然而，需要进一步研究来探讨谷氨酸转运的动态变化及其分子机制，以及谷氨酸转运对突触的影响。本研究的目的是探讨Notch通路介导谷氨酸转运和突触可塑性的调控机制。在本研究中，将3日龄、体重1.0 - 1.5 kg的雄性约克郡新生仔猪（n = 48）随机分为对照组（假手术组）和五个缺氧缺血亚组，根据不同的恢复时间，再将这些亚组进一步分为用二甲基亚砜或Notch通路抑制剂（N-[N-(3,5-二氟苯乙酰基-L-丙氨酰)]-S-苯甘氨酸叔丁酯）处理的亚组。模型建立后，对Notch通路相关蛋白、突触素和谷氨酸转运体进行免疫组织化学、免疫荧光染色和蛋白质印迹分析。此外，通过透射电子显微镜观察突触微观结构。在缺氧缺血损伤的早期（缺氧缺血后6 - 12小时），谷氨酸转运体兴奋性氨基酸转运体-2和突触素的表达下调，突触小泡数量减少，观察到突触肿胀；在缺氧缺血后12 - 24小时，Notch通路被激活，兴奋性氨基酸转运体-2和突触素表达增加，突触小泡数量略有增加。用Notch通路抑制剂处理后，兴奋性氨基酸转运体-2和突触素表达下降。这表明缺氧缺血损伤后星形胶质细胞-神经元中的谷氨酸转运受Notch通路调控，并通过突触素的表达影响囊泡释放和突触可塑性。
