Advanced Search

Journal Navigation

Journal Home

Subscriptions

Archive

Contact Us

Table of Contents

Click here for more information

Sign In to gain access to subscriptions and/or personal tools.
Journal of Biological Rhythms
This Article
Right arrow Free Full Text (Free PDF) Free
Right arrow References
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 Add to Saved Citations
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Request Reprints
Right arrow Add to My Marked Citations
Citing Articles
Right arrow Citing Articles via ISI Web of Science (3)
Right arrow Citing Articles via Google Scholar
Right arrow Citing Articles via Scopus
Google Scholar
Right arrow Articles by Bartell, P. A.
Right arrow Articles by Menaker, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bartell, P. A.
Right arrow Articles by Menaker, M.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?

Interactions between Dopamine and Melatonin Organize Circadian Rhythmicity in the Retina of the Green Iguana

Paul A. Bartell

Department of Biology, University of Virginia, Charlottesville, VA 22903, pab43{at}psu.edu

Manuel Miranda-Anaya

Department of Biology, University of Virginia, Charlottesville, VA 22903

Wilson McIvor

Department of Biology, University of Virginia, Charlottesville, VA 22903

Michael Menaker

Department of Biology, University of Virginia, Charlottesville, VA 22903

Circadian physiology in the vertebrate retina is regulated by several neurotransmitters. In the lateral eyes of the green iguana the circadian rhythm of melatonin content peaks during the night while the rhythm of dopamine peaks during the day. In the present work, the authors explore the interaction of these 2 neurotransmitters during the circadian cycle. They depleted retinal dopamine with intravitreal injections of 6-hydroxydopamine (6-OHDA) and measured ocular melatonin content in vivo throughout 1 circadian cycle. The circadian rhythm of ocular melatonin not only persisted but increased 10-fold in amplitude. This increase was substantially reduced by the intraocular administration of dopamine. 6-OHDA-treated retinas, unlike those from untreated animals, did not express a circadian rhythm of melatonin synthesis in vitro. To deplete retinal melatonin, the authors pinealectomized iguanas and blocked retinal melatonin synthesis by depleting serotonin with intraocular injections of 5,6-dihydroxytryptamine. In animals so treated, they found that the circadian rhythm of retinal dopamine content was abolished, the levels of dopamine were lowered, and the levels of dopamine metabolites were greatly increased. The data suggest that in iguanas, the amplitude of the circadian rhythm of melatonin synthesis in the eye is suppressed by dopamine while the rhythm of dopamine depends, at least in part, on the presence of melatonin.

Key Words: melatonin • dopamine • retina • circadian • serotonin • pineal

Journal of Biological Rhythms, Vol. 22, No. 6, 515-523 (2007)
DOI: 10.1177/0748730407308167
Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?