Mesopic background lights enhance dark-adapted cone ERG flash responses in the intact mouse retina: a possible role for gap junctional decoupling
Mesopic background lights enhance dark-adapted cone ERG flash responses in the intact mouse retina: a possible role for gap junctional decoupling
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DOI：
10.1152/jn.00536.2010
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发表时间：
2011-05-01
影响因子：
2.5
通讯作者：
Koskelainen, A.
中科院分区：
文献类型：
--
作者：
Heikkinen, H.;Vinberg, F.;Koskelainen, A.
Heikkinen H，Vinberg F，Nymark S，Kotchainen A.中间视觉背景光增强完整小鼠视网膜暗适应的视锥ERG闪光反应：缝隙连接去耦的可能作用。J Neurophysiol 105：2309-2318，2011.首次发表于2011年3月9日; doi：10.1152/jn.00536.2010.-在适应视杆细胞压迫背景光的过程中，小鼠视网膜电图（ERG）的视锥细胞驱动闪光反应在几分钟内增加多达两倍。这种现象的起源进行了研究，在本工作中记录preflash-isolated（M-）锥闪光反应离体在黑暗中，并在应用程序中的各种稳定的背景光。在该方案中，视锥刺激闪光之前是预闪光，该预闪光保持视杆处于饱和状态（超极化），以允许在不同的背景光水平下选择性刺激视锥。光诱导的增长被认为是代表真正的增强锥闪光反应相对于他们的黑暗适应状态。它在几分钟内发展，其整体大小是背景光强度的分级函数。在低中间视觉亮度区域的光下观察到视锥细胞反应增长的阈值强度，在该区域视杆细胞反应被部分压缩。在足以抑制类似于90%的视杆反应的强度下达到最大效果。光诱导的视锥细胞光反应的增强是不敏感的拮抗剂和激动剂的神经递质传递。然而，应用间隙连接阻滞剂的暗适应视网膜产生类似的变化，在锥闪光反应的背景光，并防止在随后的光适应进一步增长。这些结果是一致的想法，锥ERG光反应抑制暗适应小鼠视网膜杆和锥之间的缝隙连接耦合。然后，这种耦合将被中间视觉背景光逐渐可逆地去除，从而允许锥光响应的更大功能范围。
Heikkinen H, Vinberg F, Nymark S, Koskelainen A. Mesopic background lights enhance dark-adapted cone ERG flash responses in the intact mouse retina: a possible role for gap junctional decoupling. J Neurophysiol 105: 2309-2318, 2011. First published March 9, 2011; doi:10.1152/jn.00536.2010.-The cone-driven flash responses of mouse electroretinogram (ERG) increase as much as twofold over the course of several minutes during adaptation to a rod-compressing background light. The origins of this phenomenon were investigated in the present work by recording preflash-isolated (M-)cone flash responses ex vivo in darkness and during application of various steady background lights. In this protocol, the cone stimulating flash was preceded by a preflash that maintains rods under saturation (hyperpolarized) to allow selective stimulation of the cones at varying background light levels. The light-induced growth was found to represent true enhancement of cone flash responses with respect to their dark-adapted state. It developed within minutes, and its overall magnitude was a graded function of the background light intensity. The threshold intensity of cone response growth was observed with lights in the low mesopic luminance region, at which rod responses are partly compressed. Maximal effect was reached at intensities sufficient to suppress similar to 90% of the rod responses. Light-induced enhancement of the cone photoresponses was not sensitive to antagonists and agonists of glutamatergic transmission. However, applying gap junction blockers to the dark-adapted retina produced qualitatively similar changes in the cone flash responses as did background light and prevented further growth during subsequent light-adaptation. These results are consistent with the idea that cone ERG photoresponses are suppressed in the dark-adapted mouse retina by gap junctional coupling between rods and cones. This coupling would then be gradually and reversibly removed by mesopic background lights, allowing larger functional range for the cone light responses.