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G.P. Lewis, K.E. Betts, P.T. Johnson, S.K. Fisher; Changes in the Expression Patterns of Synaptic Proteins Following Retinal Detachment and Reattachment . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4212.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if there are changes in the expression patterns of synaptic proteins following retinal detachment (RD) and reattachment (RR).
Experimental RDs were created in feline eyes and the retinas harvested 3, 7 or 28 days later. RRs were performed 3–days after creating the detachment and the retinas harvested 28 days later. Immunocytochemistry was performed on 100 um Vibratome sections using various double–label combinations of antibodies to the synaptic vesicle proteins synaptophysin, synaptobrevin 2, synaptotagmin I, SV2, and Vglut 1, and the presynaptic membrane protein, SNAP–25. Their distribution was observed using an Olympus Fluoview confocal microscope. QPCR analysis was used to quantify mRNA levels for the proteins in the detached retinas.
In normal retina, synaptic protein labeling was restricted to the synaptic terminals present in the OPL and IPL. After RD, the expression level for all decreased in both plexiform layers. The pattern of expression of these proteins appeared fairly uniform across the retina in control eyes, but after RD, their expression varied, leaving the synaptic terminals non–uniformly labeled. Rod terminals that retract into the ONL after RD continued to express all of the proteins examined, albeit it at lower levels than in the normal eyes. Following RD, synaptotagmin labeling was not limited to photoreceptor terminals, but appeared to fill the cell bodies of some photoreceptors whereas SNAP–25 redistributed into the axons of some photoreceptors. Following RR, a mosaic of labeling patterns was observed across the retina ranging from areas that were near normal to those showing disrupted patterns characteristic of detached retina. QPCR analysis showed a decrease in the expression of mRNAs for all of these proteins beginning within 3 days of RD and continuing to 28 days.
RD appears to cause profound changes in the expression patterns of proteins associated with synaptic function. The pattern of labeling suggests that the transport or localization of synaptotagmin and SNAP–25 may be disrupted while the qPCR data support the immunocytochemical observations that there is reduced synthesis of all six. 28 days of RR after a 3–day detachment is not sufficient to return the pattern of expression to that observed in control retina. Our data suggest that the recovery of synaptic protein expression may be part of the complex process of retinal repair after RR and may even account for some of the variability in recovery of visual function.
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