title: Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice.
abstract: In the mammalian retina, a small subset of retinal ganglion cells (RGCs) are intrinsically photosensitive, express the opsin-like protein melanopsin, and project to brain nuclei involved in non-image-forming visual functions such as pupillary light reflex and circadian photoentrainment. We report that in mice with the melanopsin gene ablated, RGCs retrograde-labeled from the suprachiasmatic nuclei were no longer intrinsically photosensitive, although their number, morphology, and projections were unchanged. These animals showed a pupillary light reflex indistinguishable from that of the wild type at low irradiances, but at high irradiances the reflex was incomplete, a pattern that suggests that the melanopsin-associated system and the classical rod/cone system are complementary in function.
authors.affiliation: Department of Integrative and Molecular Neuroscience, Division of Neuroscience and Psychological Medicine, Faculty of Medicine, Imperial College London, Charing Cross Campus, St. Dunstans Road, London W6 8RF, UK. r.j.lucas@ic.ac.uk
authors.forename: R J
authors.initials: RJ
authors.lastname: Lucas
authors.forename: S
authors.initials: S
authors.lastname: Hattar
authors.forename: M
authors.initials: M
authors.lastname: Takao
authors.forename: D M
authors.initials: DM
authors.lastname: Berson
authors.forename: R G
authors.initials: RG
authors.lastname: Foster
authors.forename: K-W
authors.initials: KW
authors.lastname: Yau
mesh_terms: D000221:Adaptation, Ocular; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002940:Circadian Rhythm; D003624:Darkness; D008027:Light; D055537:Light Signal Transduction; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009847:Olivary Nucleus / Q000166:cytology / Q000502:physiology; D010641:Phenotype; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology; D011680:Pupil / Q000187:drug effects / Q000502:physiology*; D012025:Reflex, Pupillary; D012162:Retinal Degeneration / Q000235:genetics / Q000503:physiopathology; D012165:Retinal Ganglion Cells / Q000502:physiology*; D017299:Rod Opsins / Q000235:genetics* / Q000502:physiology*; D013493:Suprachiasmatic Nucleus / Q000502:physiology; D000099210:Melanopsin
chemical_list: D002217:Carbachol; D017299:Rod Opsins; D000099210:Melanopsin