OBJECTIVETo investigate the effects of naloxone on glutamate release in combined oxygen-glucose deprivation of primary cultured human embryo neurons.

METHODSThe primary cultured embryonic human cortical neurons were demonstrated by immunocytochemical stain of neural filament (NF). The neurons were randomly allocated into control group, hypoxic group, and experimental group. The experimental group was further divided into three subgroups pretreated with different concentrations of naloxone (0.25, 5, 10 microg/ml). The neurons of hypoxic group and experimental group were deprived both oxygen and glucose for 1 hours followed by 24 hours of reoxygenation. Meanwhile, we used 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, high performance liquid chromatography (HPLC), and biological analysis to study the survival rate of neurons and the changes of extracellular glutamate and lactate dehydrogenase (LDH) levels after 24 hours of reoxygenation.

RESULTSOne hour of oxygen-glucose deprivation followed by 24 hours of reoxygenation was associated with a large increase in extracellular LDH and glutamate and a significant decrease of cell vitality (P < 0.01). Naloxone exerted a concentration-dependent protection against neuronal injury provoked by combined oxygen-glucose deprivation. After reoxygenation, the extracellular concentrations of glutamate gradually decreased (P < 0.05, P < 0.01, respectively) and cell vitality increased (P < 0.01) with increase of the concentration of naloxone compared with control group. All of them returned to control level when naloxone was up to 10 microg/ml (P > 0.05).

CONCLUSIONNaloxone protects neurons from hypoxic injury by inhibiting the release of glutamate and therefore alleviating the exciting toxicity.