AJP - Regu Fuel your research with LabChart
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Regul Integr Comp Physiol 264: R615-R621, 1993;
0363-6119/93 $5.00
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
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 Google Scholar
Google Scholar
Right arrow Articles by Margraf, R. R.
Right arrow Articles by Lynch, G. R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Margraf, R. R.
Right arrow Articles by Lynch, G. R.

AJP - Regulatory, Integrative and Comparative Physiology, Vol 264, Issue 3 615-R621, Copyright © 1993 by American Physiological Society

ARTICLES

Melatonin injections affect circadian behavior and SCN neurophysiology in Djungarian hamsters

R. R. Margraf and G. R. Lynch
Department of Biology, Wesleyan University, Middletown, Connecticut 06459.

We investigated the effects of daily melatonin (MEL) injection on phase angle of entrainment, duration of wheel-running activity (alpha), and frequency of suprachiasmatic nuclei (SCN) neuronal discharge in the photo-nonresponsive phenotype of the Djungarian hamster, Phodopus sungorus. Photo-nonresponsiveness is characterized by an absence of physiological adjustments to short days (SD). With respect to wheel-running activity, photo-nonresponsive hamsters have a large negative phase angle of entrainment and a compressed alpha under SD. These hamsters also have a delayed nocturnal MEL pulse. These circadian differences are correlated with the daily profile of SCN neuronal activity. In the present experiments, daily MEL injections to photo-nonresponsive hamsters resulted in molt, gonadal regression, and expansion in alpha until entrainment to lights off. Vehicle-injected controls did not exhibit any of these responses. SCN neuronal activity patterns recorded from MEL-injected photo-nonresponders, but not vehicle-injected controls, resembled electrical activity profiles of photoresponsive hamsters. These results demonstrate that MEL induces "photoresponsiveness" in previously photo-nonresponsive hamsters, that MEL modifies circadian behavior to resemble that of photoresponders, and that MEL injections affect the circadian rhythm of SCN neuronal firing.


This article has been cited by other articles:


Home page
 Mol. Cell. Biol.Home page
X. Jin, C. von Gall, R. L. Pieschl, V. K. Gribkoff, J. H. Stehle, S. M. Reppert, and D. R. Weaver
Targeted Disruption of the Mouse Mel1b Melatonin Receptor
Mol. Cell. Biol., February 1, 2003; 23(3): 1054 - 1060.
[Abstract] [Full Text]

Home page
 Am. J. Physiol. Regul. Integr. Comp. Physiol.Home page
N. F. Ruby, T. Kang, and H. C. Heller
Melatonin attenuates photic disruption of circadian rhythms in Siberian hamsters
Am J Physiol Regulatory Integrative Comp Physiol, October 1, 1997; 273(4): R1540 - R1549.
[Abstract] [Full Text] [PDF]


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