title: Distribution of melanopsin positive neurons in pigmented and albino mice: evidence for melanopsin interneurons in the mouse retina.
abstract: Here we have studied the population of intrinsically photosensitive retinal ganglion cells (ipRGCs) in adult pigmented and albino mice. Our data show that although pigmented (C57Bl/6) and albino (Swiss) mice have a similar total number of ipRGCs, their distribution is slightly different: while in pigmented mice ipRGCs are more abundant in the temporal retina, in albinos the ipRGCs are more abundant in superior retina. In both strains, ipRGCs are located in the retinal periphery, in the areas of lower Brn3a(+)RGC density. Both strains also contain displaced ipRGCs (d-ipRGCs) in the inner nuclear layer (INL) that account for 14% of total ipRGCs in pigmented mice and 5% in albinos. Tracing from both superior colliculli shows that 98% (pigmented) and 97% (albino) of the total ipRGCs, become retrogradely labeled, while double immunodetection of melanopsin and Brn3a confirms that few ipRGCs express this transcription factor in mice. Rather surprisingly, application of a retrograde tracer to the optic nerve (ON) labels all ipRGCs, except for a sub-population of the d-ipRGCs (14% in pigmented and 28% in albino, respectively) and melanopsin positive cells residing in the ciliary marginal zone (CMZ) of the retina. In the CMZ, between 20% (pigmented) and 24% (albino) of the melanopsin positive cells are unlabeled by the tracer and we suggest that this may be because they fail to send an axon into the ON. As such, this study provides the first evidence for a population of melanopsin interneurons in the mammalian retina.
authors.affiliation: Departamento de Oftalmología, Facultad de Medicina, Campus de Espinardo, Universidad de Murcia, e Instituto Murciano de Investigación Biosanitaria-Hospital Clínico Universitario Virgen de la Arrixaca (IMIB-ARRIXACA) Murcia, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Valiente-Soriano
authors.affiliation: Departamento de Oftalmología, Facultad de Medicina, Campus de Espinardo, Universidad de Murcia, e Instituto Murciano de Investigación Biosanitaria-Hospital Clínico Universitario Virgen de la Arrixaca (IMIB-ARRIXACA) Murcia, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: García-Ayuso
authors.affiliation: Departamento de Oftalmología, Facultad de Medicina, Campus de Espinardo, Universidad de Murcia, e Instituto Murciano de Investigación Biosanitaria-Hospital Clínico Universitario Virgen de la Arrixaca (IMIB-ARRIXACA) Murcia, Spain.
authors.forename: Arturo
authors.initials: A
authors.lastname: Ortín-Martínez
authors.affiliation: Departamento de Oftalmología, Facultad de Medicina, Campus de Espinardo, Universidad de Murcia, e Instituto Murciano de Investigación Biosanitaria-Hospital Clínico Universitario Virgen de la Arrixaca (IMIB-ARRIXACA) Murcia, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Jiménez-López
authors.affiliation: Departamento de Oftalmología, Facultad de Medicina, Campus de Espinardo, Universidad de Murcia, e Instituto Murciano de Investigación Biosanitaria-Hospital Clínico Universitario Virgen de la Arrixaca (IMIB-ARRIXACA) Murcia, Spain.
authors.forename: Caridad
authors.initials: C
authors.lastname: Galindo-Romero
authors.affiliation: Departamento de Oftalmología, Facultad de Medicina, Campus de Espinardo, Universidad de Murcia, e Instituto Murciano de Investigación Biosanitaria-Hospital Clínico Universitario Virgen de la Arrixaca (IMIB-ARRIXACA) Murcia, Spain.
authors.forename: Maria Paz
authors.initials: MP
authors.lastname: Villegas-Pérez
authors.affiliation: Departamento de Oftalmología, Facultad de Medicina, Campus de Espinardo, Universidad de Murcia, e Instituto Murciano de Investigación Biosanitaria-Hospital Clínico Universitario Virgen de la Arrixaca (IMIB-ARRIXACA) Murcia, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Agudo-Barriuso
authors.affiliation: Department of Ocular Biology and Therapeutics, UCL-Institute of Ophthalmology London, UK.
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Vugler
authors.affiliation: Departamento de Oftalmología, Facultad de Medicina, Campus de Espinardo, Universidad de Murcia, e Instituto Murciano de Investigación Biosanitaria-Hospital Clínico Universitario Virgen de la Arrixaca (IMIB-ARRIXACA) Murcia, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Vidal-Sanz
keywords: Brn3a; OHSt-tracing; ciliary marginal zone; displaced intrinsically photosensitive retinal ganglion cells; interneuron; melanopsin retinal ganglion cells; retinal topography; spatial distribution