Dopamine enhances excitatory amino acid-gated conductances in cultured retinal horizontal cells

• Published in: Nature (London) Vol. 325; no. 6103; pp. 437 - 439
• Main Authors: Knapp, Andrew G, Dowling, John E
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 29-01-1987; Nature Publishing Group
• Subjects: 8-Bromo Cyclic Adenosine Monophosphate - pharmacology; Amino acids; Animals; Biological and medical sciences; Cells, Cultured; Cellular biology; Dopamine - pharmacology; Electric Conductivity; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Glutamates - pharmacology; Glutamic Acid; Kainic Acid - pharmacology; Light; Membrane Potentials - drug effects; Nervous system; Perches; Photoreception; Retina - drug effects; Retina - physiology; Serotonin - pharmacology; Vertebrates; Vertebrates: nervous system and sense organs; Cell culture; Dopamine; Electrophysiology; Horizontal neuron; Retina; Eye; Vertebrata; Regulation(control); Aminoacid; Pisces; Neurotransmitter; Cyclic nucleotide; AMP-3',5'; Electrical conductance; Response stimulus relation
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/325437a0

In the teleost retina, cone horizontal cells receive extensive innervation from dopaminergic interplexiform cells, and possess dopamine receptors whose activation stimulates adenylate cyclase. Exogenously applied dopamine modifies several aspects of horizontal cell activity in the intact retina, including the responsiveness of these neurons to light and the strength of electrical coupling between them. We have used whole-cell voltage clamp methods to examine whether dopamine can alter the light-responsiveness of horizontal cells by changing their sensitivity to the neurotransmitter released by the photoreceptors. We report that dopamine and cyclic AMP, although having little direct effect on resting membrane conductance, greatly enhance ionic conductances gated by kainate, an agonist of the transmitter released by the photoreceptors, and by L-glutamate, the agent proposed to be the photoreceptor transmitter. Our results provide the first direct evidence for dopaminergic regulation of excitatory amino-acid neurotransmission in the vertebrate nervous system and suggest a possible mechanism to explain the reduction in the responsiveness of horizontal cells observed when retinas are treated with dopamine.