Mechanisms regulating the marked seasonal variation in melatonin synthesis in the European hamster pineal gland.
Like many wild species, the European hamster (Cricetus cricetus) adapts to the marked seasonal changes in its environment, namely by hibernation and inhibition of sexual activity in winter. These annual functions are driven by the variation in the environmental factors (light, temperature) that are transmitted to the body through large variations in the duration and amplitude of the nocturnal melatonin rhythm. Here we report that the seasonal variation in melatonin synthesis is mainly driven by arylalkylamine N-acetyltransferase gene transcription and enzyme activation. This, however, does not exclude participation of hydroxyindole-O-methyltransferase, which may relay environmental temperature information. The in vivo experiments show that norepinephrine stimulates melatonin synthesis, this effect being gated at night. The possibility that the variation in pineal metabolism depends on a seasonal change in the suprachiasmatic nuclei clock circadian activity that is transmitted by norepinephrine is discussed.
Garidou
Marie-Laure
ML
Neurobiologie des Rythmes, Unité Mixte de Recherche-Centre National de la Recherche Scientifique 7518, Université Louis Pasteur, 67000 Strasbourg, France.
Vivien-Roels
Berthe
B
Pevet
Paul
P
Miguez
Jesus
J
Simonneaux
Valerie
V
D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002940:Circadian Rhythm; D006224:Cricetinae; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic; D008027:Light; D008297:Male; D008550:Melatonin / Q000096:biosynthesis* / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D010870:Pineal Gland / Q000378:metabolism*; D012621:Seasons; D013696:Temperature
D001191:Arylamine N-Acetyltransferase; D008550:Melatonin; D009638:Norepinephrine