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GABA‐ergic pathways in the goldfish retina
Author(s) -
Marc Robert E.,
Stell William K.,
Bok Dean,
Lam Dominic M. K.
Publication year - 1978
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.901820204
Subject(s) - depolarization , retina , darkness , biophysics , biology , intracellular , neuroscience , amacrine cell , electron microscope , anatomy , microbiology and biotechnology , optics , physics , botany
A high‐affinity uptake mechanism for [ 3 H]‐γ‐aminobutyric acid (GABA) has been localized to type H1 cone horizontal cells and type A b pyriform amacrine cells in the retina of the goldfish by light and electron microscope autoradiography. By stimulating isololated retinas with colored lights during incubation we have been able to use [ 3 H]‐GABA uptake as a probe of light‐evoked changes in membrane potential. All colors of lights increase and darkness decreases [ 3 H]‐GABA uptake by H1 cone horizontal cells. Our model of voltage dependence of GABA uptake predicts that all colors of light should hyperpolarize H1 cone horizontal cells and other investigators have shown by intracellular recording and dye‐marking that type H1 cone horizontal cells hyperpolarize to all wavelengths of light. We have also obtained evidence that dark‐induced depolarizatiion of cone horizontal cells leads to release of GABA. Type A b pyriform amacrine cells show maximal [ 3 H]‐GABA uptake in darkness and when exposed to green or blue lights, but red lights dramatically suppress uptake. We predict these neurons to be red‐depolarizing and recent intracellular recordings and dye‐marking by Famiglietti et al. ('77) support our conclusions. Synaptic relations of apparently GABA‐ergic neurons were investigated in the electron microscope. We propose type H1 cone horizontal cells to be both pre‐ and post‐synaptic to red‐sensitive cones and type A b pyriform amacrine cells to be both pre‐ and post‐synaptic to red‐sensitive center‐depolarizing bipolar cells.