Circadian rhythms in the retina of rats with photoreceptor degeneration

J Neurochem. 2004 Aug;90(4):1019-24. doi: 10.1111/j.1471-4159.2004.02571.x.


Previous studies have demonstrated that the mammalian retina contains a circadian clock system that controls several retinal functions. In mammals the location of the retinal circadian clock is unknown whereas, in non-mammalian vertebrates, earlier work has demonstrated that photoreceptor cells contain the circadian clock. New experimental evidence has suggested that in mammals the retinal circadian clock may be located outside the photoreceptor cells. In this study we report that circadian rhythms in Aa-nat mRNA (in vivo) and melatonin synthesis (in vitro) are still present in the retina of rats lacking photoreceptors. The circadian pacemaker(s) controlling such rhythms is probably located in kainic acid sensitive neurons in the inner retina since kainic acid injections abolished the rhythmicity. These data are the first direct demonstration that circadian rhythmicity in the mammalian retina can be generated independently from the photoreceptors and the suprachiasmatic nuclei of the hypothalamus.

Publication types

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

MeSH terms

  • Animals
  • Arylamine N-Acetyltransferase / genetics
  • Circadian Rhythm* / drug effects
  • Circadian Rhythm* / genetics
  • Disease Models, Animal
  • Excitatory Amino Acid Agonists / pharmacology
  • Kainic Acid / pharmacology
  • Melatonin / metabolism
  • Photoreceptor Cells, Vertebrate / pathology*
  • RNA, Messenger / metabolism
  • Rats
  • Retina / drug effects
  • Retina / metabolism*
  • Retina / pathology
  • Retinal Degeneration / genetics
  • Retinal Degeneration / metabolism*
  • Retinal Degeneration / pathology


  • Excitatory Amino Acid Agonists
  • RNA, Messenger
  • Arylamine N-Acetyltransferase
  • Melatonin
  • Kainic Acid