AJP - Regu Journal of Applied Physiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Regul Integr Comp Physiol 278: R1339-R1345, 2000;
0363-6119/00 $5.00
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (21)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ribelayga, C.
Right arrow Articles by Simonneaux, V.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ribelayga, C.
Right arrow Articles by Simonneaux, V.
Vol. 278, Issue 5, R1339-R1345, May 2000

HIOMT drives the photoperiodic changes in the amplitude of the melatonin peak of the Siberian hamster

Christophe Ribelayga, Paul Pévet, and Valérie Simonneaux

Neurobiologie des Fonctions Rythmiques et Saisonnières, Université Louis Pasteur, Unité Mixte de Recherche-Centre National de la Recherche Scientifique 7518, F-67000 Strasbourg, France

In the pineal, melatonin (Mel) is synthesized from serotonin by arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT). Although it is clear that AA-NAT drives the daily rhythm in Mel synthesis, the mechanisms involved in the photoperiodic changes of the amplitude of the Mel peak, as observed in the Siberian hamster, remain to be determined. We investigated the characteristics of AA-NAT and HIOMT in Siberian hamsters kept either under a short (SP) or a long photoperiod (LP). The amplitude of the nocturnal peak of Mel was about two times higher under SP than under LP, whereas AA-NAT activity was about two times smaller under SP. In contrast, a twofold increase of HIOMT activity was observed under SP compared with LP. No change in the affinity of the enzymes for their substrates was observed between the two photoperiods. Our data strongly suggest that the photoperiodic variations in the amplitude of the nocturnal peak of Mel are driven by HIOMT, thereby promoting an important physiological role for this enzyme in the seasonal regulation of Mel production.

hydroxyindole-O-methyltransferase; arylalkylamine-N-acetyltransferase; photoperiodism; seasonal rhythms; circadian rhythms


This article has been cited by other articles:


Home page
 Pharmacol. Rev.Home page
V. Simonneaux and C. Ribelayga
Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters
Pharmacol. Rev., June 1, 2003; 55(2): 325 - 395.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Regul. Integr. Comp. Physiol.Home page
M.-L. Garidou, B. Vivien-Roels, P. Pevet, J. Miguez, and V. Simonneaux
Mechanisms regulating the marked seasonal variation in melatonin synthesis in the European hamster pineal gland
Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2003; 284(4): R1043 - R1052.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online