Document Detail


Dopaminergic regulation of cone retinomotor movement in isolated teleost retinas: I. Induction of cone contraction is mediated by D2 receptors.
MedLine Citation:
PMID:  2869104     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In the retinas of lower vertebrates, retinal photoreceptors and melanin pigment granules of the retinal pigment epithelium (RPE) undergo characteristic movements in response to changes in light intensity and to signals from an endogenous circadian clock. To identify agents responsible for mediating light and/or circadian regulation of these retinomotor movements, we investigated the effects of hormones and neurotransmitters on cone, rod, and RPE movements in the green sunfish, Lepomis cyanellus. We report here that 3,4-dihydroxyphenylethylamine (dopamine) mimics the effect of light by inducing light-adaptive retinomotor movements in all three cell types. In isolated dark-cultured retinas, dopamine induced light-adaptive cone contraction with a half-maximal effect at 10(-8) M. This effect of dopamine was inhibited by antagonists with a potency order characteristic of D2 receptor mediation. The dopamine uptake blocker benztropine also induced light-adaptive cone contraction in isolated dark-cultured retinas, suggesting that there is continuous dopamine release in the dark but that concomitant uptake normally prevents activation of cone contraction. That dopamine plays a role in light regulation of cone movement is further suggested by the observation that light-induced cone contraction was partially inhibited by sulpiride, a selective D2 dopamine antagonist, or by Co2+, a blocker of synaptic transmission. Sulpiride also promoted dark-adaptive cone elongation in isolated light-adapted retinas, suggesting that continuous dopamine action is required in the light to maintain the light-adapted cone position. Dopamine can act directly on D2 receptors located on rod and cone inner/outer segments: dopamine induced light-adaptive retinomotor movements in isolated distal fragments of dark-adapted photoreceptors cultured in the dark. Together our results indicate that dopamine induces light-adaptive retinomotor movements in cones, rods, and RPE cells by activating D2 receptors. We suggest that, in vivo, dopamine plays a role in both light and circadian regulation of retinomotor movements.
Authors:
A Dearry; B Burnside
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of neurochemistry     Volume:  46     ISSN:  0022-3042     ISO Abbreviation:  J. Neurochem.     Publication Date:  1986 Apr 
Date Detail:
Created Date:  1986-04-16     Completed Date:  1986-04-16     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  2985190R     Medline TA:  J Neurochem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1006-21     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological
Adrenergic alpha-Antagonists / pharmacology
Animals
Calcium / pharmacology
Cobalt / pharmacology
Culture Techniques
Dark Adaptation
Dopamine / pharmacology,  physiology*
Epinephrine / pharmacology
Fishes / physiology*
Light
Movement / drug effects
Phenylephrine / pharmacology
Photoreceptor Cells / drug effects,  physiology*,  radiation effects
Pigment Epithelium of Eye / physiology,  radiation effects
Receptors, Dopamine / physiology*
Receptors, Dopamine D2
Retina / physiology*
Sulpiride / pharmacology
Grant Support
ID/Acronym/Agency:
EY03575/EY/NEI NIH HHS
Chemical
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 0/Receptors, Dopamine; 0/Receptors, Dopamine D2; 15676-16-1/Sulpiride; 51-43-4/Epinephrine; 59-42-7/Phenylephrine; 7440-48-4/Cobalt; 7440-70-2/Calcium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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