| Summary: | 碩士 === 國立陽明大學 === 解剖暨細胞生物學研究所 === 91 === Abstract
Besides neuron cells, an intercellular biochemical cascade within the central nervous system also contains a large number of neuroglia. In which, microglia phagocytize waste products of tissue cells, partake the damage treatment and formation of scar through proliferation or migration during neural development, degeneration or excitotoxicity. However, some researchers favor that microglia can excel the survival of neural cells, other study take on a more negative view that microglia tends to reduce the number of surviving neural cells. So far the role of microglia to neural cells is still undefined.
This study was designed to investigate the effects of microglia condition medium on neurons during kainate-induced excitotoxicity. In vitro, primary hippocampal neuron cultures and microglia cultures were prepared and treated with kainate. The results showed that both low and high concentration of kainate could facilitate the activation and proliferation of microglia. The microglia condition medium treated with 0 or 150μM kainate could suppress the production of ROS、reduce the death of neuron 、 and inhibit the release of the hippocampal neuron cultures during the excitotoxicity. In addition, the microglia condition medium could attenuate the increase of the phagocytosis and migration abilities of microglia induced by kainite or LPS.
In addition to neurons and microglia, there are still other cells, such as astrocytes, existing in the nervous system in vivo. In order to investigate whether the microglia condition medium still has protective effects on neurons in rats, microglia were stimulated with 150μM or 300μM kainate for 24 hours, the microglia condition medium from each treatment condition were then administered together with 1μg kainate to the hippocampus of rats by micro-injection. Seven days later, the results indicated that microglia condition medium treated with 0 or 150μM kainate both could protect pyramidal cells of CA3 of hippocampus from damage 、 inhibit the activation of microglia and astrocytes、 and prevent the release of NO from hippocampus.
However, the microglia condition medium treated with 300μM kainate could not protect pyramidal cells from damage, suggesting the excessive kainate in this medium. The possible reason why the medium treated with 0μM kainate or 150μM kainate could protect neurons from excitotoxicity is that the medium contained certain factors or cytokines which maybe modify the procedures of excitototoxicity, therefore protecting neurons and inhibiting the activation of microglia. However, the exact components or factors will be further investigated.
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