doi:10.1167/iovs.15-16808engGarcia-Ayuso DDi Pierdomenico JEsquiva GNadal-Nicolás FMPinilla ICuenca NVidal-Sanz MAgudo-Barriuso MVillegas-Pérez MP.Inherited photoreceptor degeneration causes the death of melanopsin-positive retinal ganglion cells and increases their coexpression of brn3aART-2015-92002Purpose: To study the population of intrinsically photosensitive retinal ganglion cells (melanopsin-expressing RGCs, m+RGCs) in P23H-1 rats, a rat model of inherited photoreceptor degeneration. Methods: At postnatal (P) times P30, P365, and P540, retinas from P23H dystrophic rats (line 1, rapid degeneration; and line 3, slow degeneration) and Sprague Dawley (SD) rats (control) were dissected as whole-mounts and immunodetected for melanopsin and/or Brn3a. The dendritic arborization of m+RGCs and the numbers of Brn3a+RGCs and m+RGCs were quantified and their retinal distribution and coexpression analyzed. Results: In SD rats, aging did not affect the population of Brn3a+RGCs or m+RGCs or the percentage that showed coexpression (0.27%). Young P23H-1 rats had a significantly lower number of Brn3a+RGCs and showed a further decline with age. The population of m+RGCs in young P23H-1 rats was similar to that found in SD rats and decreased by 22.6% and 28.2% at P365 and P540, respectively, similarly to the decrease of the Brn3a+RGCs. At these ages the m+RGCs showed a decrease of their dendritic arborization parameters, which was similar in both the P23H-1 and P23H-3 lines. The percentage of coexpression of Brn3a was, however, already significantly higher at P30 (3.31%) and increased significantly with age (10.65% at P540). Conclusions: Inherited photoreceptor degeneration was followed by secondary loss of Brn3a+RGCs and m+RGCs. Surviving m+RGCs showed decreased dendritic arborization parameters and increased coexpression of Brn3a and melanopsin, phenotypic and molecular changes that may represent an effort to resist degeneration and/or preferential survival of m+RGCs capable of synthesizing Brn3a.2015http://zaguan.unizar.es/record/5838910.1167/iovs.15-16808http://zaguan.unizar.es/record/58389oai:zaguan.unizar.es:58389info:eu-repo/grantAgreement/ES/ISCIII/PI13-00643info:eu-repo/grantAgreement/ES/ISCIII/PI13-01266info:eu-repo/grantAgreement/ES/ISCIII/RETICS-RD12-0034-0010info:eu-repo/grantAgreement/ES/MICINN/ISCIII-RD12-0034-0014info:eu-repo/grantAgreement/ES/MINECO/BFU2012-36845info:eu-repo/grantAgreement/ES/MINECO/SAF-2012-38328INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE 56, 8 (2015), 4592-4604byhttp://creativecommons.org/licenses/by/3.0/es/info:eu-repo/semantics/openAccess