Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice

Science. 2003 Jan 10;299(5604):245-7. 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 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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptation, Ocular
  • Animals
  • Carbachol / pharmacology
  • Circadian Rhythm
  • Darkness
  • Light Signal Transduction
  • Light*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Olivary Nucleus / cytology
  • Olivary Nucleus / physiology
  • Phenotype
  • Photoreceptor Cells, Vertebrate / physiology
  • Pupil / drug effects
  • Pupil / physiology*
  • Reflex, Pupillary*
  • Retinal Degeneration / genetics
  • Retinal Degeneration / physiopathology
  • Retinal Ganglion Cells / physiology*
  • Rod Opsins / genetics*
  • Rod Opsins / physiology*
  • Suprachiasmatic Nucleus / physiology


  • Rod Opsins
  • melanopsin
  • Carbachol