Astrocyte-Conditioned Medium Protects Prefrontal Cortical Neurons from Glutamate-Induced Cell Death by Inhibiting TNF-α Expression

Abstract

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 (p75^NTR), and TNF-α. ACM pretreatment (2 h) reversed glutamate-decreased cell viability and increased BDNF, but reduced the expression of GDNF, P75^NTR, 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, p75^NTR, 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.

Pulsed Electromagnetic Fields Stimulate HIF-1α-Independent VEGF Release in 1321N1 Human Astrocytes Protecting Neuron-like SH-SY5Y Cells from Oxygen-Glucose Deprivation

“…ACM represents a widely used in vitro model to test the protective effect of astrocyte-released factors on cultured neurons. In particular, it has been shown that ACM can promote the survival and functional recovery of neurons following different types of injury [39][40][41]. Since PEMFs exposure promoted the production of the neuroprotective factor VEGF, we tested the hypothesis that ACM obtained from PEMF-treated 1321N1 cells could protect SH-SY5Y, an extensively used model of neuron cells, from OGD-induced injury.…”

Murine Beta-Amyloid (1–42) Oligomers Disrupt Endothelial Barrier Integrity and VEGFR Signaling via Activating Astrocytes to Release Deleterious Soluble Factors

“…We prepared an astrocyte-conditioned medium (ACM) based on the protocols of several papers [62][63][64]. C8-D1A cells were cultured in DMEM at 37 • C in a humidified incubator containing 5% CO 2 .…”

Liraglutide Is Protective against Brain Injury in Mice with Febrile Seizures by Inhibiting Inflammatory Factors

“…It can cause brain injury by rising the functions of extracellular excitatory amino acids, like glutamate and inhibiting the functions of γ-aminobutyric acid receptors. TNF-α released from reactive astrocytes and activated microglia can promote the release of glutamate [8] and regulate the firing of neurons and seizures. Thus, it is essential to control the severity of neuroinflammation for preventing FS.…”