Structural and functional remodeling in the retina of a mouse with a photoreceptor synaptopathy: plasticity in the rod and degeneration in the cone system.
Knowledge about the plastic and regenerative capacity of the retina is of key importance for therapeutic approaches to restore vision in patients who suffer from degenerative retinal diseases. In the retinae of mice, mutant for the presynaptic scaffolding protein Bassoon, signal transfer at photoreceptor ribbon synapses is disturbed due to impaired ribbon attachment to the active zone. In a long-term study we observed, with light and electron microscopic immunocytochemistry and electroretinographic recordings, two overlapping events in the Bassoon mutant retina, i.e. loss of photoreceptor synapses in the outer plexiform layer, and structural remodeling and formation of ectopic photoreceptor synapses in the outer nuclear layer, a region usually devoid of synapses. Formation of ectopic synaptic sites starts around the time when photoreceptor synaptogenesis is completed in wild-type mice and progresses throughout life. The result is a dense plexus of ectopic photoreceptor synapses with significantly altered but considerable synaptic transmission. Ectopic synapse formation is led by the sprouting of horizontal cells followed by the extension of rod bipolar cell neurites that fasciculate with and grow along the horizontal cell processes. Although only the rod photoreceptors and their postsynaptic partners show structural and functional remodeling, our study demonstrates the potential of the retina for long-lasting plastic changes.
Specht
Dana
D
Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, Staudtstrasse 5, 91058 Erlangen, Germany.
Tom Dieck
Susanne
S
Ammermüller
Josef
J
Regus-Leidig
Hanna
H
Gundelfinger
Eckart Dieter
ED
Brandstätter
Johann Helmut
JH
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D004195:Disease Models, Animal; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D016253:Microscopy, Immunoelectron; D009416:Nerve Regeneration / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology; D009473:Neuronal Plasticity / Q000235:genetics*; D020127:Recovery of Function / Q000235:genetics; D051245:Retinal Bipolar Cells / Q000473:pathology / Q000502:physiology; D017949:Retinal Cone Photoreceptor Cells / Q000473:pathology / Q000503:physiopathology*; D012162:Retinal Degeneration / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D051248:Retinal Horizontal Cells / Q000473:pathology / Q000503:physiopathology; D017948:Retinal Rod Photoreceptor Cells / Q000473:pathology / Q000503:physiopathology*; D013569:Synapses / Q000235:genetics* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000235:genetics; D014785:Vision, Ocular / Q000235:genetics
C498441:Bsn protein, mouse; D009419:Nerve Tissue Proteins