Melatonin induces Cry1 expression in the pars tuberalis of the rat.
In mammals, interacting transcriptional/post-translational feedback loops involving 'clock genes' and their protein products control circadian organisation. These genes are not only expressed in the master circadian clock of the suprachiasmatic nuclei (SCN) but also in many peripheral tissues where they exhibit similar but not identical dynamic to that seen in the SCN. Among these peripheral tissues, the pars tuberalis (PT) of the pituitary expresses clock genes. We show here that the PT of the rat, like that of other rodents, rhythmically expresses Per1. We also report rhythmic expression of another clock gene, Cry1. The peak of Cry1 mRNA expression occurs during the night concomitantly with rising blood plasma melatonin concentrations. Using an acute injection paradigm, we demonstrate that Cry1 expression is directly induced by melatonin in the PT. Melatonin injection at the end of the subjective day also affects Per1 expression, leading to diminished mRNA levels. These data support the existence of a time-measurement model in the PT based on direct opposite actions of melatonin on Per1 and Cry1 expression.
Dardente
Hugues
H
Neurobiologie des Rythmes, UMR 7518 CNRS/ULP, IFR 37, 12, rue de l'université, 67000 Strasbourg, France. dardente@neurochem.u-strasbg.fr
Menet
Jérôme S
JS
Poirel
Vincent Joseph
VJ
Streicher
Dominique
D
Gauer
François
F
Vivien-Roels
Berthe
B
Klosen
Paul
P
Pévet
Paul
P
Masson-Pévet
Mireille
M
D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000235:genetics*; D018797:Cell Cycle Proteins; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D008297:Male; D008550:Melatonin / Q000097:blood* / Q000494:pharmacology; D009687:Nuclear Proteins / Q000235:genetics; D056950:Period Circadian Proteins; D017956:Photoreceptor Cells, Invertebrate; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar / Q000033:anatomy & histology / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled
D018797:Cell Cycle Proteins; C538965:Cry1 protein, rat; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D009687:Nuclear Proteins; C539024:Per1 protein, rat; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; C119828:cry protein, Drosophila; D008550:Melatonin