Department of Pathophysiology, Neuroscience Research Center, Hebei Medical University, 361 Zhongshan East Road, Shijiazhuang, Hebei, 050017, People's Republic of China.
Hebei Key Laboratory of Critical Disease Mechanism and Intervention, Hebei Medical University, Shijiazhuang, Hebei, People's Republic of China.
Amino Acids. 2021 Nov;53(11):1649-1661. doi: 10.1007/s00726-021-03088-3. Epub 2021 Oct 30.
Glutamate transporter-1 (GLT-1) removes most glutamate in the synaptic cleft. Sulbactam confers neuronal protection against ischemic insults in the hippocampal CA1 region accompanied by the upregulation of GLT-1 expression in rats. The present study further investigates the effect of sulbactam on the binding property and uptake capacity of GLT-1 for glutamate, and the change in extracellular glutamate concentration in the hippocampal CA1 region of rats with global brain ischemia. The binding property and uptake capacity of GLT-1 were measured using a radioligand binding and uptake assay, respectively, with L-H-glutamate. The extracellular glutamate concentration was detected using microdialysis and high-performance liquid chromatography-mass spectrometry. Neuropathological evaluation was performed based on thionin staining. It was shown that sulbactam pre-treatment changed GLT-1 binding property, including increased B and decreased K values, increased GLT-1 uptake capacity for glutamate, and inhibited the elevation of extracellular glutamate concentration in rats with global cerebral ischemia. These effects of sulbactam were accompanied by its neuronal protection on the hippocampal CA1 neurons against delayed neuronal death resulted from ischemic insult. Furthermore, administration of GLT-1 antisense oligodeoxynucleotides, which inhibited the expression of GLT-1, blocked the aforementioned sulbactam-related effects, which suggested that GLT-1 upregulation mediated the above effect although other mechanisms independent of the upregulation of GLT-1 expression could not be excluded. It could be concluded that sulbactam improves the binding property and uptake capacity of GLT-1 for glutamate and then reduces the glutamate concentration and excitotoxicity during global cerebral ischemia, which contributes to the neuroprotection of sulbactam against brain ischemia.
谷氨酸转运体-1（GLT-1）可清除突触间隙中的大部分谷氨酸。舒巴坦可上调大鼠海马 CA1 区神经元中 GLT-1 的表达，从而对缺血性损伤起到神经保护作用。本研究进一步探讨了舒巴坦对 GLT-1 与谷氨酸结合特性和摄取能力的影响，以及在全脑缺血大鼠海马 CA1 区细胞外谷氨酸浓度的变化。采用放射性配体结合和摄取试验分别用 L-H-谷氨酸测定 GLT-1 的结合特性和摄取能力。采用微透析和高效液相色谱-质谱联用技术检测细胞外谷氨酸浓度。根据硫堇染色进行神经病理学评估。结果表明，舒巴坦预处理可改变 GLT-1 的结合特性，包括 B 值增加和 K 值降低，增加 GLT-1 对谷氨酸的摄取能力，并抑制全脑缺血大鼠细胞外谷氨酸浓度的升高。舒巴坦的这些作用伴随着其对海马 CA1 神经元的神经保护作用，防止缺血性损伤引起的迟发性神经元死亡。此外，给予 GLT-1 反义寡核苷酸，抑制 GLT-1 的表达，可阻断上述舒巴坦相关作用，这表明 GLT-1 的上调介导了上述作用，尽管不能排除其他不依赖于 GLT-1 表达上调的机制。可以得出结论，舒巴坦可改善 GLT-1 与谷氨酸的结合特性和摄取能力，从而降低全脑缺血期间的谷氨酸浓度和兴奋性毒性，这有助于舒巴坦对脑缺血的神经保护作用。
