Development of the circadian melatonin rhythm and its responsiveness to PACAP in the embryonic chicken pineal gland.
The embryonic development of the circadian melatonin (MT) rhythm and the responsiveness of embryonic MT secretion to pituitary adenylate cyclase-activating polypeptide (PACAP) were investigated. Using dynamic in vitro bioassays, we showed the following: (1) The circadian clock and/or the intracellular signal transduction pathways connecting the clock to the MT synthesizing apparatus appear between days 16 and 18 (E16-18) of embryonic development. Lack of periodical environmental stimuli can lead to a delay in this maturation. (2) Exposure of the embryonic chicken pineal gland to PACAP induces a transitory increase in MT secretion and (3) a transitory increase in cyclic AMP efflux at or before day E13 in vitro.
Faluhelyi
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Department of Anatomy, University of Pécs Medical School, and the Neurohumoral Regulations Research Group of the Hungarian Academy of Sciences, Hungary.
Reglodi
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Csernus
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V
D000818:Animals; D002642:Chick Embryo; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008550:Melatonin / Q000378:metabolism*; D010870:Pineal Gland / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000494:pharmacology / Q000502:physiology*
D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D008550:Melatonin