Abstract
A17 amacrine cells are an important part of the scotopic pathway. Their synaptic varicosities receive glutamatergic inputs from rod bipolar cells (RBC) and release GABA onto the same RBC terminal, forming a reciprocal feedback that shapes RBC depolarization. Here, using patch-clamp recordings, we characterized electrical coupling between A17 cells of the rat retina and report the presence of strongly interconnected and non-coupled A17 cells. In coupled A17 cells, evoked currents preferentially flow out of the cell through GJs and cross-synchronization of presynaptic signals in a pair of A17 cells is correlated to their coupling degree. Moreover, we demonstrate that stimulation of one A17 cell can induce electrical and calcium transients in neighboring A17 cells, thus confirming a functional flow of information through electrical synapses in the A17 coupled network. Finally, blocking GJs caused a strong decrease in the amplitude of the inhibitory feedback onto RBCs. We therefore propose that electrical coupling between A17 cells enhances feedback onto RBCs by synchronizing and facilitating GABA release from inhibitory varicosities surrounding each RBC axon terminal. GJs between A17 cells are therefore critical in shaping the visual flow through the scotopic pathway.
Highlights
The identity of connexins proteins expressed in A17 cells is unknown
A17 cells are a fundamental part of the network for scotopic vision[20,21,24] and the second most numerous AC in the mammalian retina[50]
We provide a detailed description of electrical coupling between A17 cells and the role it plays in signal processing within the scotopic pathway
Summary
The identity of connexins proteins expressed in A17 cells is unknown. Cx36 immunolabeling can be found in the inner portion of the IPL36,53,54 but does not colocalize with A17 dendrites[36] and carbenoxolone, an effective Cx36 blocker[55], had no effect on Rin of A17 cells. Another connexin protein expressed in the IPL, such as Cx4553,56,57, may form the building blocks for A17 cell electrical synapses. Experiments using knockout mice for different connexins are required to determine the precise subtypes mediating coupling between A17 cell
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
