6533b7d7fe1ef96bd1268dff
RESEARCH PRODUCT
Circadian and Infradian Activity Rhythms in the Mammalian Pineal Body
L. Vollrathsubject
Synaptic ribbonendocrine systemmedicine.medical_specialtyChemistryGerbilBacterial circadian rhythmsMelatoninPineal glandmedicine.anatomical_structureEndocrinologyInfradian rhythmInternal medicinemedicineSerotoninCircadian rhythmhormones hormone substitutes and hormone antagonistsmedicine.drugdescription
The neuroendocrine nature of the pineal organ is well established. Linked to the optic system via postganglionic sympathetic fibres coming from the superior cervical ganglia, the parenchymal cells of the pineal synthesize serotonin from tryptophan and convert it to melatonin, the most widely studied pineal substance, and other indoleamines. Melatonin synthesis is stimulated by noradrenaline released from intrapineal sympathetic nerve fibres, involving β-adrenergic mechanisms and the adenyl cyclase-cAMP-system. The rate-limiting enzyme of melatonin formation is serotonin-N-acetyltransferase (NAT) that converts serotonin to N-acetylserotonin. Hydroxyindole-O-methyltransferase (HIOMT) catalyzes the formation of 5-methoxy-N-acetylserotonin (melatonin) from N-acetylserotonin (cf. Vollrath 1981). A typical feature of the mammalian pineal gland is a pronounced circadian rhythm of melatonin formation, that is entrained by environmental lighting conditions. The day-night ratios of melatonin formation are 1: 60 in rat, 1: 3 in hamster and Mongolian gerbil and 1: 1.5 in guinea-pig (Rudeen et al. 1975).
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1982-01-01 |