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Catherine W Morgans, Tammie L Haley, Gaoying Ren, Robert M Duvoisin; Changes in the outer plexiform layer of the retina between light- and dark-adapted states. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2758.
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© ARVO (1962-2015); The Authors (2016-present)
The retina operates over a vast range of luminance, yet synaptic mechanisms of adaptation to different background light intensities are not well understood. To gain insight into these mechanisms, we compared the abundance and distribution of key synaptic proteins in the outer plexiform layer (OPL) of light-adapted and dark-adapted mouse retina.
Mouse retinas were dissected either in the light-adapted or dark-adapted state and immediately processed for either western blotting or immunofluorescence confocal microscopy using antibodies to pre- and post-synaptic proteins.
Differences between the light- and dark-adapted states were observed in the abundance, distribution, and conformation of synaptic proteins in the OPL and ON-bipolar cells. For example, double labeling with a conformation-specific antibody to PKCα and a non-conformation sensitive PKCα antibody revealed that PKCα in ON-BPCs is active in the light-adapted state. This was confirmed by labeling for phospho-serine. Immunofluorescence imaging also revealed differences in synaptic architecture between the light- and dark-adapted states. Double labeling of bipolar cells for PKCα and Goα showed that, not only does the ratio of these two signal transduction proteins change between light- and dark-adapted states, but the bipolar cell dendrites appear longer in the dark-adapted retina. Presynaptic differences were also observed. For example, labeling for ribeye revealed that photoreceptor synaptic ribbons are larger in the light-adapted state, although the total amount of ribeye is unchanged.
Our results indicate dramatic light-dependent plasticity at photoreceptor to bipolar cells synapses that are likely to influence synaptic transmission.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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