title: Transient Downregulation of Melanopsin Expression After Retrograde Tracing or Optic Nerve Injury in Adult Rats.
abstract: OBJECTIVE
  To investigate the effect of retrograde tracing or axotomy on melanopsin mRNA expression and immunodetection in albino and pigmented rat retinas.
  
  
  METHODS
  Groups were (1) intact-naïve retinas; (2) optic nerve crush (ONC) analyzed at 7 days (7d) or 2 months (2m); (3) Fluorogold (FG) tracing from the superior colliculi (SCi) analyzed at 7d or 2m; (4) tracing from the intact optic nerve (ON) with FG or hydroxystilbamidine methanesulfonate (OHSt), analyzed 3d later; and (5) sham tracing from the ON or sham surgery. Brn3a and melanopsin were double stained in whole mounts to quantify and assess the distribution of orthotopic and displaced Brn3a(+) retinal ganglion cells (Brn3a(+)RGCs) and melanopsin(+)RGCs (m(+)RGCs). Freshly dissected retinas were used for melanopsin mRNA quantitative PCR.
  
  
  RESULTS
  Tracing from the SCi did not affect the number of Brn3a(+)RGCs or m(+)RGCs counted in pigmented rats. However, only 55% of m(+)RGCs were immunodetected in albinos at 7d, although by 2m the m(+)RGCs counts returned to normal. Optic nerve tracing had a more dramatic effect (38% or 77% of m(+)RGCs were immunodetected in albino or pigmented rats) that occurred irrespectively of the tracer (OHSt or FG). This effect was not observed in the sham groups. After ONC, Brn3a(+)RGCs decreased to 37% and 8% by 7d and 2m, respectively. Melanopsin (+)RGC counts diminished to 30% at 7d, but recovered to 49% of controls by 2m. Melanopsin mRNA was downregulated after ON tracing or 7d after ONC, but did not differ from intact values 2m after ONC.
  
  
  CONCLUSIONS
  Following ON injury or retrograde tracing there is a transient melanopsin downregulation that should be taken into account when assessing m(+)RGC survival.
authors.affiliation: Instituto Murciano de Investigación Biosanitaria-VIRGEN DE LA ARRIXACA (IMIB-ARRIXACA), Murcia, Spain 2Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Murcia, Spain.
authors.forename: Francisco M
authors.initials: FM
authors.lastname: Nadal-Nicolás
authors.affiliation: Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
authors.forename: Maria H
authors.initials: MH
authors.lastname: Madeira
authors.affiliation: Instituto Murciano de Investigación Biosanitaria-VIRGEN DE LA ARRIXACA (IMIB-ARRIXACA), Murcia, Spain 2Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Murcia, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Salinas-Navarro
authors.affiliation: Instituto Murciano de Investigación Biosanitaria-VIRGEN DE LA ARRIXACA (IMIB-ARRIXACA), Murcia, Spain 2Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Murcia, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Jiménez-López
authors.affiliation: Instituto Murciano de Investigación Biosanitaria-VIRGEN DE LA ARRIXACA (IMIB-ARRIXACA), Murcia, Spain 2Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Murcia, Spain.
authors.forename: Caridad
authors.initials: C
authors.lastname: Galindo-Romero
authors.affiliation: Instituto Murciano de Investigación Biosanitaria-VIRGEN DE LA ARRIXACA (IMIB-ARRIXACA), Murcia, Spain 2Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Murcia, Spain.
authors.forename: Arturo
authors.initials: A
authors.lastname: Ortín-Martínez
authors.affiliation: Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Coimbra, Portugal 4Center for Neuroscience and Cell Biology-IBILI, University of Coimbra, Coimbra, Portugal 5Association for Innovation and Biomedical.
authors.forename: Ana Raquel
authors.initials: AR
authors.lastname: Santiago
authors.affiliation: Instituto Murciano de Investigación Biosanitaria-VIRGEN DE LA ARRIXACA (IMIB-ARRIXACA), Murcia, Spain 2Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Murcia, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Vidal-Sanz
authors.affiliation: Instituto Murciano de Investigación Biosanitaria-VIRGEN DE LA ARRIXACA (IMIB-ARRIXACA), Murcia, Spain 2Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Murcia, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Agudo-Barriuso
mesh_terms: D000818:Animals; D015536:Down-Regulation; D005786:Gene Expression Regulation; D020221:Optic Nerve Injuries / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D017299:Rod Opsins / Q000096:biosynthesis / Q000235:genetics*; D000099210:Melanopsin
chemical_list: D012313:RNA; D017299:Rod Opsins; D000099210:Melanopsin