Genetic, temporal and developmental differences between melatonin rhythm generating systems in the teleost fish pineal organ and retina

J Neuroendocrinol. 2003 Apr;15(4):378-82. doi: 10.1046/j.1365-2826.2003.00993.x.


Complete melatonin rhythm generating systems, including photodetector, circadian clock and melatonin synthesis machinery, are located within individual photoreceptor cells in two sites in Teleost fish: the pineal organ and retina. In both, light regulates daily variations in melatonin secretion by controlling the activity of arylalkylamine N-acetyltransferase (AANAT). However, in each species examined to date, marked differences exist between the two organs which may involve the genes encoding the photopigments, genes encoding AANAT, the times of day at which AANAT activity and melatonin production peak and the developmental schedule. We review the fish pineal and retinal melatonin rhythm generating systems and consider the evolutional pressures and other factors which led to these differences.

Publication types

  • Review

MeSH terms

  • Animals
  • Arylamine N-Acetyltransferase / genetics
  • Biological Clocks / genetics
  • Biological Clocks / physiology*
  • Circadian Rhythm / genetics
  • Circadian Rhythm / physiology*
  • Fishes / genetics
  • Fishes / physiology*
  • Gene Expression Regulation / physiology
  • Gene Expression Regulation / radiation effects
  • Light
  • Light Signal Transduction / genetics
  • Melatonin / genetics
  • Melatonin / metabolism
  • Melatonin / physiology*
  • Photoreceptor Cells, Vertebrate / physiology*
  • Photoreceptor Cells, Vertebrate / radiation effects
  • Pineal Gland / metabolism
  • Pineal Gland / physiology*
  • RNA, Messenger / metabolism
  • Retina / metabolism
  • Retina / physiology*
  • Retinal Pigments / physiology
  • Species Specificity


  • RNA, Messenger
  • Retinal Pigments
  • Arylamine N-Acetyltransferase
  • Melatonin