Melanopsin in cells of origin of the retinohypothalamic tract

Nat Neurosci. 2001 Dec;4(12):1165. doi: 10.1038/nn768.


All known eukaryotic organisms exhibit physiological and behavioral rhythms termed circadian rhythms that cycle with a near-24-hour period; in mammals, light is the most potent stimulus for entraining endogenous rhythms to the daily light cycle. Photic information is transmitted via the retinohypothalamic tract (RHT) to the suprachiasmatic nucleus (SCN) in the hypothalamus, where circadian rhythms are generated, but the retinal photopigment that mediates circadian entrainment has remained elusive. Here we show that most retinal ganglion cells (RGCs) that project to the SCN express the photopigment melanopsin.

Publication types

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

MeSH terms

  • Animals
  • Circadian Rhythm / physiology*
  • Fluorescent Dyes
  • Functional Laterality / physiology
  • Light Signal Transduction / physiology
  • Neural Pathways / cytology
  • Neural Pathways / metabolism*
  • Photic Stimulation
  • RNA, Messenger / metabolism
  • Rats
  • Retinal Ganglion Cells / cytology
  • Retinal Ganglion Cells / metabolism*
  • Rod Opsins / genetics*
  • Stilbamidines*
  • Suprachiasmatic Nucleus / cytology
  • Suprachiasmatic Nucleus / metabolism*


  • 2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt
  • Fluorescent Dyes
  • RNA, Messenger
  • Rod Opsins
  • Stilbamidines
  • melanopsin