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2‐Amino‐4‐Phosphonobutyric Acid Exerts a Light‐Dependent Effect on Post‐Gabaculine Levels of Retinal γ‐Aminobutyric Acid (GABA): Evidence that ON Synaptic Pathways Regulate Retinal GABAergic Transmission
Author(s) -
Cubells Joseph F.,
Ndubuka Christopher,
Makman Maynard H.
Publication year - 1991
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1991.tb02097.x
Subject(s) - retinal , gabaergic , kainic acid , retina , gamma aminobutyric acid , glutamate receptor , neurotransmission , gaba transaminase , biology , neuroscience , glutamate decarboxylase , pharmacology , biochemistry , microbiology and biotechnology , chemistry , inhibitory postsynaptic potential , receptor , enzyme
The effects of light, 2‐amino‐4‐phosphonobutyric acid (APB), and kainic acid on rat retinal γ‐aminobutyric acid (GABA)‐ergic transmission were studied by measuring levels of retinal GABA following subcutaneous injection of gabaculine, an irreversible inhibitor of GABA‐transaminase. Post‐gabaculine levels of retinal GABA in light‐exposed rats were significantly greater than those in rats held in darkness. The synaptic mechanism of this effect of light was examined by measuring post‐gabaculine levels of retinal GABA in rats placed into either lighted or darkened conditions after receiving unilateral intravitreal injections of APB, a glutamate analogue that selectively decreases the activity of ON synaptic pathways in the retina. APB attenuated the post‐gabaculine accumulation of GABA in rats held in the light, but not in those placed into darkness. Furthermore, the light‐dependent increment in post‐gabacu line accumulation of retinal GABA was entirely APB sensitive, and the effect of APB was entirely light dependent. In contrast to APB, kainic acid stimulated the post‐gabaculine accumulation of retinal GABA in vivo. Our findings suggest that APB and kainic acid influence GABAergic transmission at different sites in the retina and that some retinal GABAergic neurons are either ON or ON‐OFF amacrine cells.