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Decrease of endogenous vasopressin release necessary for expression of the circadian rise in plasma corticosterone: a
A Kalsbeek1, J van der Vliet, R M Buijs
1Netherlands Institute for Brain Research, Amsterdam, The Netherlands.
Journal of Neuroendocrinology
|April 1, 1996
Summary
The suprachiasmatic nucleus (SCN) uses vasopressin (VP) to control corticosterone rhythms. VP inhibits adrenal activity during the day, but an excitatory signal is also needed for the full circadian pattern.
Area of Science:
- Neuroendocrinology
- Circadian Biology
- Chronobiology
Background:
- Mammalian suprachiasmatic nucleus (SCN) generates daily rhythms.
- SCN influences brain activity via rhythmic neurotransmitter release.
- Circadian control of corticosterone release is not fully understood.
Purpose of the Study:
- Investigate vasopressin's role in circadian control of corticosterone.
- Elucidate SCN's mechanism for regulating the hypothalamo-pituitary-adrenal (HPA) axis.
Main Methods:
- Microdialysis-mediated intracerebral administration of vasopressin (VP) and V(1) antagonist.
- In vivo studies on freely moving, undisturbed animals.
- Measurement of plasma corticosterone levels.
Main Results:
- VP V(1) antagonist in the dorsomedial hypothalamus increased corticosterone during the light period's trough.
- VP administration at the end of the light period prevented the diurnal corticosterone rise.
- SCN-derived VP has an inhibitory role on the HPA axis during the day.
Conclusions:
- SCN-derived VP inhibits the HPA axis during the day, setting the window for corticosterone peaks.
- A decline in VP release allows for the daily corticosterone peak.
- Both inhibitory and excitatory SCN signals are necessary for the complete circadian corticosterone profile.