Morphology and visual pigment content of photoreceptors from injured goldfish retina

Adult teleost fish retinas can regenerate neurons following either surgical or pharmacological injury. The cellular milieu of the damaged retina withi n which regenerated neurons are produced might be different in these two mo del systems of retinal injury, and thus the phenotypic attributes of regene rated neurons in the two model systems might also differ. To determine if t he phenotypic attributes of photoreceptors, and by extension the recovery o f vision, are different between these two model systems, we compared the vi sual pigment content and morphology of photoreceptors derived from goldfish retinas of both models with control retina. Visual pigments-which consist of a protein moiety (opsin) and a chromophore-were analyzed in single, isol ated photoreceptors using microspectrophotometric techniques. We report tha t visual pigments and photoreceptor morphologies in the surgical model clos ely matched those of native retina. In contrast, neither photoreceptor morp hology nor visual pigment content matched closely in the pharmacological mo del. The results indicate that phenotypic attributes of photoreceptors can differ significantly between the two model systems of retinal regeneration, but that in both systems, rod- and cone-mediated visual functions can pote ntially be reestablished.