GABA transaminase in cyprinid fish retina: Localization and effects of inhibitors on temporal characteristics of S-potentials.
Cellular localization and physiology of GABA-transaminase have been studied in the cyprinid fish retina. Immunohistochemical localization of the enzyme in the goldfish retina revealed a broad distribution pattern, including both outer and inner plexiform layers. Well known inhibitors of GABA-transaminase activity, such as gabaculine and ?-vinyl-GABA, caused an improvement of the temporal frequency transfer functions of luminosity type horizontal cells in the roach retina. In contrast, bicuculline had the opposite effect. Results suggest that GABA-transaminase has a physiological role in the retina consistent with the hypothesis that GABAergic (negative) feed-back from horizontal cells to cones regulates the temporal characteristics of light-evoked electrical activity in the outer plexiform layer.
Prince
D J
DJ
Imperial College, Department of Pure and Applied Biology, London, SW7 2BB, U.K.
Djamgoz
M B
MB
Karten
H J
HJ