Abstract
Purpose :
Gap junctions between retinal ganglion cells (RGCs) and amacrine cells (ACs) are important in visual information transmission. In the mouse retina, ON αRGCs are coupled to displaced ACs, and OFF αRGCs are coupled to conventional ACs and other OFF αRGCs. This study is to investigate the role of gap junctions in synchronization and cell driving activities in the mouse retina.
Methods :
Adult C57BL/6J wild-type mice were used. Electrical activities of RGCs or ACs in the retina were recorded by patch-clamp. In the first part, two cells activities were recorded by green (525 nm) light stimuli. SKF38393 (10µM) and SCH23390 (5µM), which are agonist and antagonist for dopamine receptor 1 (D1), were applied to study the effect of ACs coupling to RGCs synchronization. Currents were injected into one cell in whole-cell mode, and the other cell activity was recorded. In the second part, viral vectors carrying a fusion construct of channelrodopsin2 (ChR2) and green fluorescent protein (GFP) were injected into the intravitreal space of both eyes and kept for 5 days before euthanized. A blue (460 nm) light was used as stimulus. The electrical recordings were performed between one ChR2-expressed cell and one non-ChR2-expressed cell.
Results :
The synchronous firings in ganglion cells layer: ON αRGCs, OFF αRGCs and ON αRGC-displaced AC were investigated. The synchrony between these couplings could be abolished by gap junction blocker-MFA (50 µM) or 18β (30 µM). D1 agonist decreased the correlations of synchrony, while D1 antagonists increased the correlations. This suggested coupling between ACs decreased the synchronous correlations of RGCs. Injecting currents into one cell could induce spikes in the coupled cell. After virus transduction, the ChR2-expressed cells could fire without chemical input. More importantly, light-evoked spiking activity of a ChR2-expressed AC drove the activity of a non-ChR2 expressed RGC, gap junction blocker MFA diminished this activity.
Conclusions :
Coupling of ACs affected synchronization between ON or OFF αRGCs. ACs could drive RGCs firing through gap junctions and vice versa. Gap junctions underlie the arbitrary manipulation of one cell by the other cell or external stimuli.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.