Pineal photoreceptors rhythmically secrete melatonin

Gary E. Pickard, Wai Xing Tang

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Individual pineal cells secrete melatonin with a circadian period, reducing a vertebrate circadian system to the level of a single cell [Brain Res., 627 (1993) 141-146]. In the present study, dissociated pineal cells were identified as melatonin-secreting by a reverse hemolytic plaque assay (RHPA) and all melatonin-secreting cells were immuno-positive when analyzed for the photoreceptor protein S-antigen. The results are the first direct evidence that isolated photoreceptor cells secrete melatonin and taken together with our previous findings indicate that single pineal cells contain: (1) a circadian oscillator; (2) a photoreceptive capacity; and (3) the ability to secrete melatonin rhythmically.

Original languageEnglish (US)
Pages (from-to)109-112
Number of pages4
JournalNeuroscience Letters
Issue number1-2
StatePublished - Apr 25 1994
Externally publishedYes


  • Anolis
  • Circadian rhythm
  • Melatonin
  • Photoreceptor
  • Pineal gland
  • Reverse hemolytic plaque assay

ASJC Scopus subject areas

  • General Neuroscience


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