Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Circadian regulation of retinomotor movements. I. Interaction of melatonin and dopamine in the control of cone length.

Circadian regulation of retinomotor movements. I. Interaction of melatonin and dopamine in the... In lower vertebrates, cone retinomotor movements occur in response to changes in lighting conditions and to an endogenous circadian clock. In the light, cone myoids contract, while in the dark, they elongate. In order to test the hypothesis that melatonin and dopamine may be involved in the regulation of cone movement, we have used an in vitro eyecup preparation from Xenopus laevis that sustains light- and dark-adaptive cone retinomotor movement. Melatonin mimics darkness by causing cone elongation. Dark- and melatonin-induced cone elongation are blocked by dopamine. Dopamine also stimulates cone contraction in dark-adapted eyecups. The effect of dopamine appears to be mediated specifically by a dopamine receptor, possibly of the D2 type. The dopamine agonist apomorphine and the putative D2 agonist LY171555 induced cone contraction. In contrast, the putative D1 agonist SKF38393-A and specific alpha 1-, alpha 2-, and beta-adrenergic receptor agonists were without effect. Furthermore, the dopamine antagonist spiroperidol not only blocked light-induced cone contraction, but also stimulated cone elongation in the light. These results suggest that dopamine is part of the light signal for cone contraction, and that its suppression is part of the dark signal for cone elongation. Melatonin may affect cone movement indirectly through its influence on the dopaminergic system. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of General Physiology Rockefeller University Press

Circadian regulation of retinomotor movements. I. Interaction of melatonin and dopamine in the control of cone length.

Pierce, M E; Besharse, J C
The Journal of General Physiology , Volume 86 (5): 671 – Nov 1, 1985
Download PDF
19 pages

Loading next page...
 
/lp/rockefeller-university-press/circadian-regulation-of-retinomotor-movements-i-interaction-of-amqJARkU1I

References (62)

Publisher
Rockefeller University Press
Copyright
© 1985 Rockefeller University Press
ISSN
0022-1295
eISSN
1540-7748
DOI
10.1085/jgp.86.5.671
Publisher site
See Article on Publisher Site

Abstract

In lower vertebrates, cone retinomotor movements occur in response to changes in lighting conditions and to an endogenous circadian clock. In the light, cone myoids contract, while in the dark, they elongate. In order to test the hypothesis that melatonin and dopamine may be involved in the regulation of cone movement, we have used an in vitro eyecup preparation from Xenopus laevis that sustains light- and dark-adaptive cone retinomotor movement. Melatonin mimics darkness by causing cone elongation. Dark- and melatonin-induced cone elongation are blocked by dopamine. Dopamine also stimulates cone contraction in dark-adapted eyecups. The effect of dopamine appears to be mediated specifically by a dopamine receptor, possibly of the D2 type. The dopamine agonist apomorphine and the putative D2 agonist LY171555 induced cone contraction. In contrast, the putative D1 agonist SKF38393-A and specific alpha 1-, alpha 2-, and beta-adrenergic receptor agonists were without effect. Furthermore, the dopamine antagonist spiroperidol not only blocked light-induced cone contraction, but also stimulated cone elongation in the light. These results suggest that dopamine is part of the light signal for cone contraction, and that its suppression is part of the dark signal for cone elongation. Melatonin may affect cone movement indirectly through its influence on the dopaminergic system.

Journal

The Journal of General Physiology – Rockefeller University Press

Published: Nov 1, 1985

There are no references for this article.