Development of the circadian melatonin rhythm and the effect of PACAP on melatonin release in the embryonic chicken pineal gland. An in vitro study.
Pituitary adenylate cyclase activating polypeptide (PACAP) has been shown to participate in modulation of circadian rhythm and to stimulate melatonin (MT) secretion in both the rat and chicken pineal glands. In contrast to mammals, the main regulator of circadian rhythm in birds is the pineal gland, which begins its rhythmic MT production already during embryonic life. In the present study, we investigated the development of MT secretion in explanted embryonic chicken pineals and their responsiveness to PACAP in a perifusion system. Our results show that: (1) the circadian clock and/or the intracellular signal transduction system connecting the clock to MT synthesizing apparatus develop between the embryonic days 16-18 (E16-18), even in vitro. (2) Exposure of the embryonic chicken pineal gland to PACAP induces transitory increase in MT secretion but does not induce visible phase shift in the circadian rhythm. (3) Cyclic AMP (cAMP) efflux also responds to PACAP at or before day E13 in embryonic chicken pineal gland in vitro.
Faluhelyi
Nándor
N
Department of Anatomy, University of Pécs Medical School, and Neurohumoral Regulations Research Group of the Hungarian Academy of Sciences, Szigeti u 12, Pécs 7624, Hungary.
Reglodi
Dóra
D
Lengvári
István
I
Csernus
Valér
V
D000818:Animals; D002642:Chick Embryo; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism; D066298:In Vitro Techniques; D008550:Melatonin / Q000378:metabolism*; D009414:Nerve Growth Factors / Q000494:pharmacology* / Q000502:physiology; D009479:Neuropeptides / Q000494:pharmacology* / Q000502:physiology; D018377:Neurotransmitter Agents / Q000494:pharmacology* / Q000502:physiology; D010870:Pineal Gland / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051381:Rats; D015398:Signal Transduction
C495403:Adcyap1 protein, rat; D009414:Nerve Growth Factors; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D000242:Cyclic AMP; D008550:Melatonin