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Intracellular calcium release resulting from mGluR1 receptor activation modulates GABA A currents in wide‐field retinal amacrine cells: a study with caffeine
Author(s) -
Vigh Jozsef,
Lasater Eric M.
Publication year - 2003
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2003.02652.x
Subject(s) - excitatory postsynaptic potential , postsynaptic potential , neuroscience , amacrine cell , inhibitory postsynaptic potential , ryanodine receptor , retinal waves , chemistry , biology , retina , glutamate receptor , microbiology and biotechnology , intracellular , receptor , retinal ganglion cell , biochemistry , intrinsically photosensitive retinal ganglion cells
The modulatory action of calcium (Ca 2+ ) released from intracellular stores on GABA A receptor‐mediated current was investigated in wide‐field amacrine cells isolated from the teleost, Morone chrysops, retina. Caffeine, ryanodine or inositol 1,4,5‐triphosphate (IP 3 ) markedly inhibited the GABA A current by elevating [Ca 2+ ] i . The inhibition resulted from the activation of a Ca 2+ → Ca 2+ /calmodulin → calcineurin cascade. Long (>12 s) exposure to glutamate mimicked the caffeine effect, i.e. it inhibited the GABA A current by elevating [Ca 2+ ] i through mGluR1 receptor activation and consequent IP 3 generation. This pathway provides a ‘timed’ disinhibitory mechanism to potentiate excitatory postsynaptic potentials in wide‐field amacrine cells. It occurs as a result of the suppression of GABA‐mediated conductances as a function of the duration of presynaptic excitatory input activity. This is much like some forms of long‐term potentiation in the central nervous system. In a local retinal circuit this will selectively accentuate particular excitatory inputs to the wide‐field amacrine cell. Similar to other neural systems, we suggest that activity‐dependent postsynaptic disinhibition is an important feature of the signal processing in the inner retina.