Gliotoxic Action of Glutamate on Cultured Astrocytes

Abstract

Abstract:Because of the well-documented importance of glutamate clearance by astrocytes in protecting neurons against excitotoxicity, it was interesting to examine whether L-glutamate exerts a toxic action on cultured astrocytes. Cell damage was evaluated by measuring activity of lactate dehydrogenase (LDH) released into the culture medium. Exposure of astrocyte cultures of the neonatal rat cerebral cortex to L-glutamate resulted in a concentration-and time-dependent increase in the release of LDH. L-Glutamate-induced gliotoxicity appeared to be mediated predominantly by the increase of oxidative stress because the reduced glutathione content and its effects were almost completely blocked by vitamin E and pyrrolidinedithiocarbamate. To support this notion further, the supplementation or depletion of intracellular reduced glutathione content attenuated or worsened Lglutamate toxicity, respectively. Activation of the glutamate transporter mimicked the action of L-glutamate on astrocytes. In addition, degrees of cell damage were not directly correlated to the levels of glutamate uptake. Moreover, the mechanism of this toxicity required energy and macromolecular synthesis. Taken together, brief exposure to L-glutamate resulted in glutamate uptake and cell swelling, whereas sustained exposure injured astrocytes via oxidative stress instead of the excitatory mechanism.

CXCL16 Orchestrates Adenosine A3Receptor and MCP-1/CCL2 Activity to Protect Neurons from Excitotoxic Cell Death in the CNS

“…We decided to investigate the possible role of CXCL16 in protecting neurons from cell death following Glu-excitotoxic insult (100 M, 30 min). In this experimental condition Glu induces specific neuronal cell death without affecting glial cells (Chen et al, 2000;Lauro et al, 2010). When CXCL16 was administrated during Glu challenge, neuronal cell death was reduced in a concentrationdependent way, as shown in Figure 3A (n ϭ 5-9; p Ͻ 0.05).…”

“…was removed and stored for later usage; neurons were washed and stimulated with Glu (100 M, 30 min) in modified Locke's buffer (without MgCl 2 plus 1 M glycine to stimulate all types of Glu receptors) in the presence or in the absence of CXCL16, hCX 3 CL1, or hCCL2 (100 nM) (Peprotech). Under these experimental conditions, only neurons die (Chen et al, 2000;Lauro et al, 2010). After treatment, cells were reincubated in the original c.m.…”

Distribution of the Cystine/Glutamate Antiporter System x−cin the Brain, Kidney, and Duodenum

“…Low levels of cystine or elevated levels of glutamate in the culture media have similar effects on cytotoxicity. This phenomenon has been described in neuroblastoma-primary retina hybrid cells and primary rat hippocampal neurons (Murphy et al 1989), primary rat embryonic cortical neurons (Murphy and Baraban 1990;, astrocytes (Chen et al 2000), and oligodendrocytes (Oka et al 1993) and has been extensively studied in HT22 cells (Tan et al 1998;Satoh et al 2004). The glutamate-mediated inhibition of cystine uptake into cells leads to a decrease in GSH, which results in oxidative stress and a form of programmed cell death called oxytosis (Tan et al 2001).…”

MCI-186 (3-Methyl-1-phenyl-2-pyrazolin-5-one) Attenuated Simulated Ischemia/Reperfusion Injury in Cultured Rat Hippocampal Cells

“…These cells were further cultured for 2 h in an incubator at 37°C. 12) Then the cells were removed from the chamber and maintained in the regular incubator with the addition of 5.5 mM glucose for 24 h of reoxygenation. All parameters were detected after 24 h of reoxygenation.…”