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Light increases the gap junctional coupling of retinal ganglion cells
Author(s) -
Hu Edward H.,
Pan Feng,
Völgyi Béla,
Bloomfield Stewart A.
Publication year - 2010
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2010.193268
Subject(s) - coupling (piping) , retina , dopaminergic , biophysics , gap junction , biology , adaptation (eye) , photopic vision , retinal , neuroscience , electrophysiology , dopamine , chemistry , intracellular , microbiology and biotechnology , biochemistry , materials science , metallurgy
We examined the effect of light adaptation on the gap junctional coupling of α‐ganglion cells (α‐GCs) in rabbit and mouse retinas. We assayed changes in coupling by measuring parameters of tracer coupling following injection of α‐GCs with Neurobiotin and the concerted spike activity of α‐GC neighbours under dark‐ and light‐adapted conditions. We found that light adaptation using mesopic or photopic background lights resulted in a dramatic increase in the labelling intensity, number, and spatial extent of ganglion and amacrine cells coupled to OFF α‐GCs when compared to levels seen under dark adaptation. While this augmentation of coupling by light did not produce an increase in the concerted spontaneous activity of OFF α‐GC neighbours, it did significantly increase correlated light‐evoked spiking. This was seen as an increase in the number of correlated spikes for α‐GC neighbours and an extension of correlations to second‐tier neighbours that was not seen under dark‐adapted conditions. Pharmacological studies in the rabbit retina indicated that dopamine mediates the observed changes in coupling by differentially activating D1 and D2 receptors under different adaptation states. In this scheme, activation of dopamine D1 receptors following light exposure triggers cAMP‐mediated intracellular pathways resulting in an increase in gap junctional conductance. Overall, our results indicate that as we move from night to day there is an enhanced electrical coupling between α‐GCs, thereby increasing the concerted activity believed to strengthen the capacity and efficiency of information flow across the optic nerve.