Abstract
Purpose: :
S-opsin is a photo-pigment expressed in short-wavelenght sensitive cones (S-cones) and is essential to support color vision. We investigated the effects of rods death on the distribution of S-opsin-positive cells in retinal-degeneration (RD) rats.
Methods: :
For control, Copenhagen rats (Harlan, Indianapolis, IN) of both sexes were used. In turn, we used pigmented S-334ter-line-3 rats, expressing a mutated human-rhodopsin protein, as an RD model. Rats were sacrificed at postnatal (P) days P21, P90, P180, and P600. Control and RD animals were maintained on a daily 12 h light/dark cycle. We studied the morphology, distribution, and identity of S-opsin positive cells in the control and RD rats by immunocytochemistry.
Results: :
In control retina, S-opsin immunoreactivity was present in S-cone photoreceptors. However, in RD retinas, from P90 onwards, the somata of S-opsin positive cells were in the outermost part of the inner nuclear layer (INL). Their processes extended toward the outer plexiform layer (OPL). Double-labeling experiments demonstrated that this cell was neither a horizontal cell nor a bipolar cell. Rather, the distal S-opsin cell appears to be a remodeled S-cone photoreceptor, by being arrestin, transducin, and recoverin immunoreactive.
Conclusions: :
Our results show that S-cones suffer morphological changes in RD rats. Co-localization of arrestin and transducin in S-opsin positive cells of the RD retina, implies that they may have some phototransduction functionality.
Keywords: retinal degenerations: cell biology • photoreceptors • plasticity