Cyclic AMP and protein kinase A rhythmicity in the mammalian suprachiasmatic nuclei

The levels of cyclic AMP and protein kinase A, as well as the activity of this enzyme, were measured in the hamster suprachiasmatic nuclei at different time points throughout the daily or circadian cycle. Significant diurnal variations for levels of AMPc and the catalytic subunit of protein kinase A...

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Bibliographic Details
Published in:Brain research 2000-03, Vol.858 (1), p.33-39
Main Authors: Ferreyra, Gabriela A, Golombek, Diego A
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Biological Clocks - drug effects
Biological Clocks - radiation effects
Blotting, Western
Circadian rhythm
Circadian Rhythm - physiology
Cricetinae
Cyclic AMP
Cyclic AMP - metabolism
Cyclic AMP-Dependent Protein Kinases - metabolism
Darkness
Fundamental and applied biological sciences. Psychology
Hormones and neuropeptides. Regulation
Hypothalamus. Hypophysis. Epiphysis. Urophysis
In Vitro Techniques
Light
Male
Melatonin
Melatonin - metabolism
Melatonin - pharmacology
Mesocricetus
Mesocricetus auratus
Neuropeptide Y - metabolism
Neuropeptide Y - pharmacology
Periodicity
Photic Stimulation
Protein kinase A
Suprachiasmatic nuclei
Suprachiasmatic Nucleus - enzymology
Vertebrates: endocrinology
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Summary:The levels of cyclic AMP and protein kinase A, as well as the activity of this enzyme, were measured in the hamster suprachiasmatic nuclei at different time points throughout the daily or circadian cycle. Significant diurnal variations for levels of AMPc and the catalytic subunit of protein kinase A and the activity of this enzyme were found. All of these parameters tended to increase throughout the nocturnal phase, reaching higher values at the end of the night and the beginning of the day and minimal values around the time of lights off. This rhythmicity appears to be under exogenous control, since constant darkness abolished fluctuations throughout the circadian cycle. In vitro incubation in the presence of melatonin during the day significantly decreased cyclic AMP levels and basal protein kinase A activity in the SCN, while neither neuropeptide Y nor light pulses affected these parameters. These results suggest a significant diurnal regulation of the cyclic AMP-dependent system in the hamster circadian clock.
ISSN:0006-8993
1872-6240
DOI:10.1016/S0006-8993(99)02390-2