Premium
GABA A and GABA C receptors in adult porcine cones: evidence from a photoreceptor‐glia co‐culture model
Author(s) -
Picaud Serge,
Pattnaik Bikash,
Hicks David,
Forster Valérie,
Fontaine Valérie,
Sahel José,
Dreyfus Henri
Publication year - 1998
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 - 10.1111/j.1469-7793.1998.033by.x
Subject(s) - retina , bicuculline , receptor , gabaa receptor , biology , neuroscience , inhibitory postsynaptic potential , gamma aminobutyric acid , gaba receptor , microbiology and biotechnology , growth cone , retinal , biophysics , axon , biochemistry
1 Edge contrast enhancement is an integrated visual function based on the complex centre‐surround organization of the cone photoreceptor light response. While centre responses result from direct light activation, surround responses are thought to result from lateral inhibition mediated by horizontal cells. This feedback signal has been attributed to GABA A receptors which have been found in lower vertebrate cones. 2 In order to study the GABA response of adult mammalian photoreceptors, we designed a culture system consisting of isolated photoreceptors seeded on a layer of retinal glial cells. Mature rods and cones required the presence of Müller glial cells to survive and develop neurites; they degenerated in the absence of glial cells. 3 Cone photoreceptors generated large GABA responses whereas rod photoreceptors did not respond to GABA applications. 4 Cone GABA responses consisted of two distinct components, one suppressed by the GABA A receptor blockers bicuculline and SR95531, and the second by the GABA C receptor antagonists TPMPA and imidazole‐4‐acetic acid (I4AA). Pentobarbital greatly increased the GABA A receptor component whereas it did not affect, or even reduced, the GABA C receptor component. During long GABA applications, GABA A receptor currents desensitized by 78 %, contrasting with the sustained GABA C response. 5 Expression of GABA C receptors in cone photoreceptors was confirmed by anti‐ρ‐subunit immunolabelling of porcine retinal sections. 6 These results indicate that both GABA A and GABA C receptors may participate in the feedback synapse from horizontal cells to cone photoreceptors in the mammalian retina.