Diminished Pupillary Light Reflex at High Irradiances in Melanopsin-Knockout Mice

• Published in: Science (American Association for the Advancement of Science) Vol. 299; no. 5604; pp. 245 - 247
• Main Authors: Lucas, R. J., Hattar, S., Takao, M., Berson, D. M., Foster, R. G., K. -W. Yau
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 10.01.2003
• Subjects: Adaptation, Ocular; Animals; Biological and medical sciences; Carbachol - pharmacology; Circadian Rhythm; Circles; Darkness; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Genotypes; Irradiance; Light; Light Signal Transduction; Mammals; Mice; Mice, Inbred C57BL; Mice, Knockout; Mops; Olivary Nucleus - cytology; Olivary Nucleus - physiology; Phenotype; Photons; Photoreceptor Cells, Vertebrate - physiology; Pupil (Eye); Pupil - drug effects; Pupil - physiology; Pupil size; Pupillary light reflex; Pupillary reflex; Reflex, Pupillary; Retina; Retinal Degeneration - genetics; Retinal Degeneration - physiopathology; Retinal Ganglion Cells - physiology; Rod Opsins - genetics; Rod Opsins - physiology; Suprachiasmatic Nucleus - physiology; Testing; Vertebrates: nervous system and sense organs; Eye; Pupil; Visual system; Vertebrata; Mammalia; Mouse; Analog; Rodentia; Pupillary reflex; Opsin; Mutation
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1077293

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 supra-chiasmatic 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.