Ontogeny of circadian and light regulation of melatonin release in Xenopus laevis embryos

Carla B. Green, Mei Ying Liang, Brooke M. Steenhard, Joseph C. Besharse

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

The retinal photoreceptors of Xenopus laevis contain a circadian clock that controls the synthesis and release of melatonin, resulting in high levels during the night and low levels during the day. Light is also an important regulator of melatonin synthesis and acts directly to acutely suppress melatonin synthesis during the day and indirectly to entrain the circadian clock. We examined the development of circadian and light regulation of melatonin release in Xenopus retinas and pineal glands. Pineal glands are capable of making measurable melatonin in culture soon after they evaginate from the diencephalon at stage 26. In cyclic light, the melatonin rhythms are robust, with higher overall levels and greater amplitudes than in constant darkness. However, the rhythm of melatonin release damps strongly and quickly toward baseline in constant darkness. Similar results are observed in older (stage 47) embryos, indicating that cyclic light has a positive effect on melatonin synthesis in this tissue. Optic vesicles dissected at stage 26 do not release melatonin in culture until the second or third day. It is weakly rhythmic in cyclic light, but in constant dark it is released at constitutively high levels throughout the day. By stage 41, the eyes release melatonin rhythmically in both cyclic light and constant darkness with similar amplitude. Our results show that Xenopus embryos develop a functional, photoresponsive circadian clock in the eye within the first few days of life and that rhythmic melatonin release from the pineal gland at comparable stages is highly dependent on a light-dark cycle. Copyright (C) 1999 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)109-116
Number of pages8
JournalDevelopmental Brain Research
Volume117
Issue number1
DOIs
StatePublished - Oct 20 1999

Fingerprint

Xenopus laevis
Melatonin
Embryonic Structures
Light
Circadian Clocks
Pineal Gland
Darkness
Xenopus
Diencephalon
Vertebrate Photoreceptor Cells
Photoperiod
Retina

Keywords

  • Development
  • Photoreceptor
  • Pineal gland
  • Retina

ASJC Scopus subject areas

  • Developmental Biology
  • Developmental Neuroscience

Cite this

Ontogeny of circadian and light regulation of melatonin release in Xenopus laevis embryos. / Green, Carla B.; Liang, Mei Ying; Steenhard, Brooke M.; Besharse, Joseph C.

In: Developmental Brain Research, Vol. 117, No. 1, 20.10.1999, p. 109-116.

Research output: Contribution to journalArticle

Green, Carla B. ; Liang, Mei Ying ; Steenhard, Brooke M. ; Besharse, Joseph C. / Ontogeny of circadian and light regulation of melatonin release in Xenopus laevis embryos. In: Developmental Brain Research. 1999 ; Vol. 117, No. 1. pp. 109-116.
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