Willbold, Elmar ; Huhn, Jutta ; Korf, Horst-Werner ; Voisin, Pierre ; Layer, Paul G. (2002)
Light-dark and circadian melatonin rhythms are established de novo in re-aggregates of the embryonic chicken retina.
In: Developmental neuroscience, 24 (6)
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
A central function of chicken photoreceptors is the rhythmic synthesis of the neurohormone melatonin; however, it is unclear how they can achieve--already before hatching (i.e. without light exposure)--a circadian pacemaker system. Here we studied melatonin synthesis and secretion in rosetted spheroids, which are de novo histotypic spheres, re-aggregated from dissociated retinal cells of chicken embryos. Spheroids were cultured during a 12-hour light/12-hour dark cycle. Shortly after the onset of photoreceptor differentiation in spheroids near day 5 in culture, melatonin secretion set in and, by day 8 in culture, showed distinct dark-light oscillations, with high values during the dark and lower ones during the light period. Concomitantly, expression of two key enzymes of melatonin synthesis, arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT) was detected by northern blot analysis from day 6 onwards, increasing until day 8. Only HIOMT, but not AA-NAT levels were 2- to 3-fold higher at the end of the light compared with the dark phase. Even under permanent darkness, a slight melatonin oscillation was revealed after 6 days. In conclusion, photoreceptors in de novo regenerated retinal spheroids become light-responsive, establish appropriate pathways for melatonin synthesis and secrete more melatonin in the dark. The underlying circadian pacemaker seems to depend on photoreceptor differentiation, not on previous light-dark entrainment.
Typ des Eintrags: | Artikel |
---|---|
Erschienen: | 2002 |
Autor(en): | Willbold, Elmar ; Huhn, Jutta ; Korf, Horst-Werner ; Voisin, Pierre ; Layer, Paul G. |
Art des Eintrags: | Bibliographie |
Titel: | Light-dark and circadian melatonin rhythms are established de novo in re-aggregates of the embryonic chicken retina. |
Sprache: | Englisch |
Publikationsjahr: | 2002 |
Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Developmental neuroscience |
Jahrgang/Volume einer Zeitschrift: | 24 |
(Heft-)Nummer: | 6 |
Kurzbeschreibung (Abstract): | A central function of chicken photoreceptors is the rhythmic synthesis of the neurohormone melatonin; however, it is unclear how they can achieve--already before hatching (i.e. without light exposure)--a circadian pacemaker system. Here we studied melatonin synthesis and secretion in rosetted spheroids, which are de novo histotypic spheres, re-aggregated from dissociated retinal cells of chicken embryos. Spheroids were cultured during a 12-hour light/12-hour dark cycle. Shortly after the onset of photoreceptor differentiation in spheroids near day 5 in culture, melatonin secretion set in and, by day 8 in culture, showed distinct dark-light oscillations, with high values during the dark and lower ones during the light period. Concomitantly, expression of two key enzymes of melatonin synthesis, arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT) was detected by northern blot analysis from day 6 onwards, increasing until day 8. Only HIOMT, but not AA-NAT levels were 2- to 3-fold higher at the end of the light compared with the dark phase. Even under permanent darkness, a slight melatonin oscillation was revealed after 6 days. In conclusion, photoreceptors in de novo regenerated retinal spheroids become light-responsive, establish appropriate pathways for melatonin synthesis and secrete more melatonin in the dark. The underlying circadian pacemaker seems to depend on photoreceptor differentiation, not on previous light-dark entrainment. |
Fachbereich(e)/-gebiet(e): | 10 Fachbereich Biologie ?? fb10_zoologie ?? 10 Fachbereich Biologie > Developmental Biology and Neurogenetics |
Hinterlegungsdatum: | 21 Nov 2011 09:54 |
Letzte Änderung: | 05 Mär 2013 09:55 |
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