OBJECTIVE Both excitotoxicity and neurotrophin deficiency may contribute to the etiology of depression and neurodegeneration. Astrocytes not only regulate glutamate metabolism and clearance, they also produce neurotrophins in the brain. However, the direct interaction between neurons and astrocytes remains unknown. METHODS This study evaluated the cellular mechanisms by which astrocyte-conditioned medium (ACM) protects prefrontal cortical neurons from glutamate-induced death by measuring cell viability and morphology as well as mRNA and protein expression of brain-derived neurotrophic factor (BDNF), BDNF receptors, glial cell line-derived neurotrophic factor (GDNF), and the proinflammatory cytokine, tumor necrosis factor (TNF)-α. Neurons and astrocytes were purified from the brains of neonatal 1-day-old Sprague-Dawley rats. ACM was harvested after exposing astrocytes to culture medium containing 100 μM glutamate for 48 h. RESULTS Glutamate insult (100 μM for 6 h) significantly reduced neuronal cell viability and increased the mRNA expression of BDNF. Glutamate (24 h) decreased neuronal viability and the expression of BDNF, but increased mRNA expression of GFAP, p75 neurotrophin receptor (p75NTR), and TNF-α. ACM pretreatment (2 h) reversed glutamate-decreased cell viability and increased BDNF, but reduced the expression of GDNF, P75NTR, and TNF-α at the mRNA level. Western blotting generally confirmed the mRNA expression following 24 glutamate insults. Furthermore, the glutamate-induced decrease in the protein expression of BDNF and full-length TrkB receptor and increase in pro-BDNF, truncated TrkB isoform 1 receptor, p75NTR, GDNF, and TNF-α were significantly attenuated by ACM pretreatment. CONCLUSIONS The study demonstrates that ACM exerts neuroprotective effects on cell viability, and this effect is most likely mediated through the modulation of neurotrophin and TNF-α expression.

中文翻译：

---

星形胶质细胞形成的培养基可通过抑制TNF-α表达来保护前额叶皮质神经元免受谷氨酸诱导的细胞死亡。

目的兴奋性毒性和神经营养蛋白缺乏可能与抑郁症和神经退行性变的病因有关。星状细胞不仅调节谷氨酸的代谢和清除，而且还在大脑中产生神经营养蛋白。但是，神经元和星形胶质细胞之间的直接相互作用仍然是未知的。方法这项研究评估了星形胶质细胞条件培养基（ACM）通过测量细胞活力和形态以及脑源性神经营养因子（BDNF），BDNF受体的mRNA和蛋白表达来保护谷氨酸诱导的前额皮层神经元死亡的细胞机制。 ，神经胶质细胞源性神经营养因子（GDNF）和促炎细胞因子，肿瘤坏死因子（TNF）-α。从新生的1天大的Sprague-Dawley大鼠的大脑中纯化神经元和星形胶质细胞。将星形胶质细胞暴露于含有100μM谷氨酸的培养基48小时后，收获ACM。结果谷氨酸损伤（100μM，6 h）显着降低神经元细胞活力并增加BDNF的mRNA表达。谷氨酸（24 h）降低神经元活力和BDNF的表达，但增加GFAP，p75神经营养蛋白受体（p75NTR）和TNF-α的mRNA表达。ACM预处理（2小时）逆转了谷氨酸降低的细胞活力并增加了BDNF，但在mRNA水平降低了GDNF，P75NTR和TNF-α的表达。Western blotting通常证实了24次谷氨酸损伤后的mRNA表达。此外，谷氨酸诱导的BDNF和全长TrkB受体蛋白表达降低，而pro-BDNF，截短的TrkB亚型1受体，p75NTR，GDNF升高，ACM预处理可显着降低TNF-α和TNF-α。结论该研究表明ACM对细胞活力具有神经保护作用，而这种作用很可能是通过调节神经营养蛋白和TNF-α的表达来介导的。