Synaptic inhibition by glycine acting at a metabotropic receptor in tiger salamander retina
Glycine is the lone fast neurotransmitter for which a metabotropic pathway has not been identified. In retina, we found a strychnine-insensitive glycine response in bipolar and ganglion cells. This glycine response reduced high voltage-activated calcium current. It was G-protein mediated and protein...
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Veröffentlicht in: | The Journal of physiology 2008-06, Vol.586 (12), p.2913-2926 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Glycine is the lone fast neurotransmitter for which a metabotropic pathway has not been identified. In retina, we found a
strychnine-insensitive glycine response in bipolar and ganglion cells. This glycine response reduced high voltage-activated
calcium current. It was G-protein mediated and protein kinase A dependent. The EC 50 of the metabotropic glycine response is 3 μ m , an order of magnitude lower than the ionotropic glycine receptor in the same retina. The bipolar cell glutamatergic input
to ganglion cells was suppressed by metabotropic glycine action. The synaptic output of about two-thirds of bipolar cells
and calcium current in two-thirds of ganglion cells are sensitive to the action of glycine at metabotropic receptors, suggesting
this signal regulates specific synaptic pathways in proximal retina. This study resolves the curious absence of a metabotropic
glycine pathway in the nervous system and reveals that the major fast inhibitory neurotransmitters, GABA and glycine, both
activate G-protein-coupled pathways as well. |
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ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1113/jphysiol.2008.153437 |