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Synaptic inhibition by glycine acting at a metabotropic receptor in tiger salamander retina
Author(s) -
Hou Mingli,
Duan Lei,
Slaughter Malcolm M.
Publication year - 2008
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2008.153437
Subject(s) - glycine receptor , strychnine , metabotropic glutamate receptor , metabotropic receptor , metabotropic glutamate receptor 7 , neuroscience , metabotropic glutamate receptor 6 , biology , metabotropic glutamate receptor 5 , inhibitory postsynaptic potential , microbiology and biotechnology , chemistry , glycine , biochemistry , glutamate receptor , receptor , amino acid
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.