Interaction Between Hippocampal Neuron and Microglia in Kainate-induced Excitotoxicity ：In Vitro Studies

• Main Authors: Hsang-Yu Chou, 周翔宇
• Other Authors: Yu-Show Fu
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/00585794897710167090

碩士 === 國立陽明大學 === 解剖暨細胞生物學研究所 === 89 === The amino acid L-Glutamate is a rather crucial form of excitatory neurotransmitter commonly found in many vertebrates’ central nervous systems. While KA receptors are a form of ionotropic receptor within Glutamate receptors that provide Na2+ permeability and response fast synaptic transmission. KA receptors are made of several subunits, including GluR5, GluR6, GluR7, KA1 and KA2. KA receptors that contain varied subunits tend to provide a varied degree of Ca2+ permeability, hence the response and result of the specific excitotoxity can also vary. Besides neuron cells, an intercellular biochemical cascade within the central nervous system also contains a large number of neuroglia. In which, microgia 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 microgia can excel the survival of neural cells, other study take on a more negative view that microgia tends to reduce the number of surviving neural cells. So far the role of microgia to neural cells is still undefined. As the experiment intends to examine the correlation of neural cells and microgia in a KA-stimulated excitotoxity process, we first begin by preparing hippocampal neuron culture and microglial culture, which are then given kainate, in order to observe the response of hippocampal neural cells and microgial cells. Next, the KA-stimulated hippocampal neuron conditional medium (NCM) is then treated with microgial cells, with which to observe the response how microgia reacts to neural cells under an excitatory stage. Meanwhile, the KA-stimulated microgial conditional medium (MCM) is also treated with hippocampal neural cells. The process has been intended to decipher via the two-way reaction the specific response and role that the hippocampal neural cells and microgial cells under KA-induced excitotoxicity. Experimental findings reveal that a 150mM of KA causes no impact to the microgial cells; nevertheless, the same 150mM of KA can damage the hippocampal neural cells and increase ROS formation. During the process, NCM tends to damage microgia with the presence of increased ROS production and the release of NO, and activates the microgial cells. While twice the dosage, or 300mM of KA, can damage neurons, and sufficiently increase the microgial cells ROS generation, cause a large amount of NO release, and activate the microgial cells at the same time. During the process, MCM serves to protect the hippocampal neural cells by reducing the ROS formation, hence attenuate the damage of KA to the hippocampal neural cells. Moreover, KA receptor subunits GluR5 - 7, KA-1 mRNA and proteins have been validated in the microgial cells with a low affinity constant (KD=208.79 nM) using 3H-kinate binding assay, indicating that only a high concentration of KA can trigger the microgial cells to process physiological responses.