Functional significance of localization of the Na channel in retinal A2 amacrine cells

视网膜A2无长突细胞Na通道定位的功能意义

• 批准号: 15500289
• 负责人: WATANABE Shu-ichi
• 金额: $ 2.18万
• 依托单位: Saitama Medical School
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15500289/
• 关键词: retina; AII amacrine cell; action potential; voltage-dependent Na channel; messenger RNA; glutamate; localization; parvalbumin; paravalbumin; アマクリン細胞; イオンチャネル; 視覚; 神経回路網; 杆体経路; パッチクランプ法; 免疫組織化学

Retinal AII amacrine cells transmit light information from rod bipolar cells to cone bipolar cells. It has been reported that AII amacrine cells generate action potentials of 10-20 mV in amplitude. In the present research, we elucidated (1)detailed properties of action potentials generated in the AII amacrine cell, (2)localization of the Na current within the AII amacrine cell, and (3)localization of Nav subunit within the retina. We obtained following results.(1)(by Tamalu & Watanabe) Frequency of the action potential was 1)decreased depending on the concentration of glutamate locally applied to the dendrite of the rod bipolar cells, 2)increased depending on the concentration of glutamate locally applied to the arboreal dendrites of the AII amacrine cell, 3)increased depending on the intensity of injected current into the soma.(2)(by Tamalu) TTX locally applied to the lobular appendage and soma most strongly inhibited the Na current compared to the application to the arboreal dendrite. Therefore, Nav may distribute mainly around the lobular appendage where voltage-dependent Ca channels are mostly localized. Also we found that activation voltage of the Ca current coincides with voltage range of the action potential.(3)(by Kaneko, Arita & Nakahira) In situ hybridization (ISH) experiments revealed that Nav 1.1 were localized in cells that had the soma on the border between the inner nuclear layer and inner plexiform layer. Double staining of antibodies against parvalbumin (a marker of the AII amacrine cell) and ISH showed that Nav 1.1 expressing cells were parvalbumin-immunopositive cells.In conclusion we found that (1)intensity of the light is coded by frequency of the action potential, that (2)Nav subtype expressed in the AII amacrine cell is Nav 1.1, that (3)Nav are localized around the output synapse, and that (4)the action potential is generated around the output synapse and facilitates activation of voltage-dependent Ca channels.

视网膜AII无大细胞从杆双极细胞向锥双极细胞传输光信息。据报道，AII无分细胞在振幅中产生10-20 mV的作用电位。在本研究中，我们阐明了（1）在AII无大细胞中产生的作用电位的详细特性，（2）Na电流在AII amarcrine细胞中的定位，以及（3）视网膜内NAV亚基的定位。我们获得了以下结果。（1）（通过塔玛鲁和渡边）的动作电位的频率为1）减少，具体取决于局部应用于杆双极细胞的谷氨酸的浓度，2）根据局部应用于谷氨酸的浓度，取决于谷氨酸的浓度，将其浓度施加到AIII III AmaCrine Dendrites中，这会增加浓度3），3）浓度增加了3）效果3） Soma。（2）（由Tamalu）局部应用于小叶附属物，并且与在树木木甲氧石中的应用相比，最强抑制了Na电流。因此，NAV可能主要在卵形附属物周围分布，其中依赖电压的CA通道大部分是局部的。我们还发现，CA电流的激活电压与动作电位的电压范围一致。（3）（由Kaneko，Arita＆Nakahira）原位杂交（ISH）实验表明，NAV 1.1位于在内部核层和内胎层之间具有soma的细胞中定位于细胞。对抗白蛋白的抗体（AII无大细胞的标志物）的抗体进行双重染色，ISH表明NAV 1.1表达细胞是白蛋白蛋白 - 免疫阳性细胞。突触，（4）动作电位是在输出突触周围产生的，并促进了电压依赖性CA通道的激活。

项目成果

Tamalu F, Nakahira K, Watanabe S-I: "Role of signal in signal processing of retinal AII amacrine cells"Japanese Journal of Physiology. Supplement(in press). (2004)

Tamalu F、Nakahira K、Watanabe S-I：“信号在视网膜 AII 无长突细胞信号处理中的作用”日本生理学杂志。

Arita K, Nakahira K, Watanabe S-I: "Voltage-dependent Na^+ channel immunoreactive processes in the inner plexiform layer of the retina"Japanese Journal of Physiology. Supplement(in press). (2004)

Arita K、Nakahira K、Watanabe S-I：“视网膜内丛状层中的电压依赖性 Na^2 通道免疫反应过程”日本生理学杂志。