Vitamin A is a necessary factor for sympathetic-independent rhythmic activation of mitogen-activated protein kinase in the rat pineal gland.
The circadian clock in the suprachiasmatic nucleus (SCN) controls day-to-day physiology and behavior by sending timing messages to multiple peripheral oscillators. In the pineal gland, a major SCN target, circadian events are believed to be driven exclusively by the rhythmic release of norepinephrine from superior cervical ganglia (SCG) neurons relaying clock messages through a polysynaptic pathway. Here we show in rat an SCN-driven daily rhythm of pineal MAPK activation that is not dependent on the SCG and whose maintenance requires vitamin A as a blood-borne factor. This finding challenges the dogma that SCG-released norepinephrine is an exclusive mediator of SCN-pineal communication and allows the assumption that humoral mechanisms are involved in pineal integration of temporal messages.
Guillaumond
F
F
EA Laboratoire d'Interactions Fonctionnelles Neuroendocriniennes.
Giraudet
F
F
Becquet
D
D
Sage
D
D
Laforge-Anglade
G
G
Bosler
O
O
François-Bellan
A M
AM
D000320:Adrenergic Fibers / Q000502:physiology*; D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D004789:Enzyme Activation / Q000502:physiology; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010870:Pineal Gland / Q000201:enzymology* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014801:Vitamin A / Q000097:blood*
D014801:Vitamin A; D020928:Mitogen-Activated Protein Kinases