鲫鱼视网膜水平细胞谷氨酸受体对γ-氨基丁酸转运体的调控
发布时间：2019-05-18 17:15
【摘要】： 水平细胞是视网膜内核层的抑制性中间神经元,接受来自光感受器细胞的谷氨酸能输入,同时通过GABA转运体释放GABA,参与水平细胞对光感受器细胞的反馈调节,及双极细胞和神经节细胞的中心外周拮抗的感受野的形成。谷氨酸可以激活水平细胞膜上的包括NMDA受体和AMPA受体在内的谷氨酸受体。已有报道证明激活鳐鱼视网膜水平细胞的AMPA受体可以抑制GABA转运体电流。我们应用全细胞膜片钳技术,在鲫鱼视网膜上也发现了类似的现象,激活鲫鱼视网膜水平细胞的AMPA受体也可以抑制GABA转运体电流。由于NMDA受体是最近在鲫鱼水平细胞上发现的,其功能尚不清楚。我们因此对激活NMDA受体是否能调节GABA转运体电流进行了研究。实验结果显示,激活水平细胞的NMDA受体可以抑制GABA转运体电流。NMDA受体的阻断剂AP-5(100μM)可以消除这个效应。说明这种效应是通过激活NMDA受体来实现的。当使用无钙的Ringer’s液灌流的时候,这种NMDA对GABA转运体的抑制就会被解除。当胞内钙库的钙释放和回收被20μM ryanodine + 2μM thapsigargin灌流3 min所阻断后,NMDA对GABA转运体的抑制作用也会被减弱。在全细胞模式膜片钳形成的时候,电极内液中10 mM的BAPTA经5 min扩散到细胞内后,这种NMDA的抑制效应也被削弱。以上结果说明激活NMDA受体可以通过影响胞内钙过程来调节GABA转运体的活动。进一步地,基于本实验室以前的工作,用数学方程构建了一个含有内质网膜和细胞膜的细胞模型来定量地分析NMDA引起的Ca2+动力学及GABA转运体电流的变化。模型结果提示,胞内钙库活动参与NMDA受体对GABA转运体活动的调节。 除了鲫鱼,在大鼠和人的视网膜水平细胞上也存在NMDA受体,但是水平细胞上NMDA受体的生理功能尚不清楚。本文在鲫鱼视网膜水平细胞上发现激活NMDA受体可以抑制GABA转运体的活动。在生理条件下,视网膜光感受器细胞在暗中持续释放谷氨酸,水平细胞上的钙通透的AMPA受体和NMDA受体均会被激活,胞外钙离子就会通过这两种受体进入胞内,发挥抑制GABA转运体的作用。相对于AMPA受体的快速失敏,NMDA受体的失敏很慢。提示生理条件下NMDA受体在对GABA转运体的抑制性调控可能发挥更重要的作用。
[Abstract]:Horizontal cells are inhibitory intermediate neurons in the inner nuclear layer of the Retin. they receive glutamic acid input from photoreceptor cells and release GABA, through GABA transporter to participate in the feedback regulation of horizontal cells to photoreceptor cells. And the formation of central peripheral antagonistic receptive fields of bipolar cells and ganglion cells. Glutamate can activate glutamate receptors on horizontal cell membrane, including NMDA receptor and AMPA receptor. It has been reported that activating AMPA receptors in horizontal cells of rays can inhibit GABA transporter current. Using whole-cell patch clamp technique, a similar phenomenon was found in the retinal of crucian carp. The activation of AMPA receptor in the horizontal cells of crucian carp can also inhibit the current of GABA transporter. Because NMDA receptor was recently found in crucian carp horizontal cells, its function is not clear. Therefore, we studied whether the activation of NMDA receptor can regulate the current of GABA transporter. The results showed that the activation of NMDA receptor in horizontal cells could inhibit the current of GABA transporter. AP-5 (100 渭 M), the blocker of NMDA receptor, could eliminate this effect. It is suggested that this effect is achieved by activating NMDA receptor. When perfused with calcium-free Ringer's solution, the inhibition of GABA transporter by this NMDA is relieved. When the calcium release and recovery of intracellular calcium pool were blocked by 20 渭 M ryanodine 2 渭 M thapsigargin perfusion for 3 min, the inhibitory effect of NMDA on GABA transporter was also weakened. When the whole cell mode patch clamp was formed, the inhibitory effect of 10 mM BAPTA in the electrode solution was also weakened after 5 min diffusion into the cell. These results suggest that the activation of NMDA receptor can regulate the activity of GABA transporter by affecting the intracellular calcium process. Furthermore, based on the previous work in our laboratory, a cell model containing endoplasmic reticulum and cell membrane was constructed by mathematical equation to quantitatively analyze the changes of Ca2 kinetics and GABA transporter current induced by NMDA. The results of the model suggest that intracellular calcium pool activity is involved in the regulation of GABA transporter activity by NMDA receptors. In addition to crucian carp, NMDA receptors also exist in rat and human retinal horizontal cells, but the physiological function of NMDA receptors in horizontal cells is not clear. It was found that activation of NMDA receptor could inhibit the activity of GABA transporter in horizontal cells of crucian carp. Under physiological conditions, retinal photoreceptor cells continue to release glutamate in the dark, calcium permeable AMPA receptors and NMDA receptors on horizontal cells will be activated, and extracellular calcium ions will enter the cells through these two receptors. Play an important role in inhibiting GABA transporter. Compared with the rapid desensitization of AMPA receptor, the desensitization of NMDA receptor is very slow. It is suggested that NMDA receptor may play a more important role in the inhibitory regulation of GABA transporter under physiological conditions.
【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2009
【分类号】：R33
本文编号：2480189
[Abstract]:Horizontal cells are inhibitory intermediate neurons in the inner nuclear layer of the Retin. they receive glutamic acid input from photoreceptor cells and release GABA, through GABA transporter to participate in the feedback regulation of horizontal cells to photoreceptor cells. And the formation of central peripheral antagonistic receptive fields of bipolar cells and ganglion cells. Glutamate can activate glutamate receptors on horizontal cell membrane, including NMDA receptor and AMPA receptor. It has been reported that activating AMPA receptors in horizontal cells of rays can inhibit GABA transporter current. Using whole-cell patch clamp technique, a similar phenomenon was found in the retinal of crucian carp. The activation of AMPA receptor in the horizontal cells of crucian carp can also inhibit the current of GABA transporter. Because NMDA receptor was recently found in crucian carp horizontal cells, its function is not clear. Therefore, we studied whether the activation of NMDA receptor can regulate the current of GABA transporter. The results showed that the activation of NMDA receptor in horizontal cells could inhibit the current of GABA transporter. AP-5 (100 渭 M), the blocker of NMDA receptor, could eliminate this effect. It is suggested that this effect is achieved by activating NMDA receptor. When perfused with calcium-free Ringer's solution, the inhibition of GABA transporter by this NMDA is relieved. When the calcium release and recovery of intracellular calcium pool were blocked by 20 渭 M ryanodine 2 渭 M thapsigargin perfusion for 3 min, the inhibitory effect of NMDA on GABA transporter was also weakened. When the whole cell mode patch clamp was formed, the inhibitory effect of 10 mM BAPTA in the electrode solution was also weakened after 5 min diffusion into the cell. These results suggest that the activation of NMDA receptor can regulate the activity of GABA transporter by affecting the intracellular calcium process. Furthermore, based on the previous work in our laboratory, a cell model containing endoplasmic reticulum and cell membrane was constructed by mathematical equation to quantitatively analyze the changes of Ca2 kinetics and GABA transporter current induced by NMDA. The results of the model suggest that intracellular calcium pool activity is involved in the regulation of GABA transporter activity by NMDA receptors. In addition to crucian carp, NMDA receptors also exist in rat and human retinal horizontal cells, but the physiological function of NMDA receptors in horizontal cells is not clear. It was found that activation of NMDA receptor could inhibit the activity of GABA transporter in horizontal cells of crucian carp. Under physiological conditions, retinal photoreceptor cells continue to release glutamate in the dark, calcium permeable AMPA receptors and NMDA receptors on horizontal cells will be activated, and extracellular calcium ions will enter the cells through these two receptors. Play an important role in inhibiting GABA transporter. Compared with the rapid desensitization of AMPA receptor, the desensitization of NMDA receptor is very slow. It is suggested that NMDA receptor may play a more important role in the inhibitory regulation of GABA transporter under physiological conditions.
【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2009
【分类号】：R33
【引证文献】
相关硕士学位论文 前1条
1 张雅婷;胞外锌离子对鲫鱼视网膜水平细胞上表达的内向整流钾通道的调控特性[D];上海交通大学;2011年
，本文编号：2480189
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