The involvement of gamma-aminobutyric acid in the organization of cat retinal ganglion cell receptive fields. A study with picrotoxin and bicuculline.

Abstract

A B S T R A C T The effects of picrotoxin and bicuculline upon the discharge pattern of center-surround organized cat retinal ganglion cells of X and Y type were studied. All experiments were carried out under scotopic or possibly low mesopic conditions; mostly but not exclusively on-center cells were studied. Stimuli were chosen so that responses were either: (a) "purely" central; (b) surround dominated; or (c) clearly mixed but center dominated. In each case a pre-drug control response was established, the drug was administered intravenously, and its subsequent effect upon the response was observed. In Y cells both picrotoxin and bicuculline caused the center-driven component of the response to become somewhat reduced in magnitude, while the surround component was substantially reduced. There was thus a change in center-surround balance in favor of the center-driven component. Responses of X cells remained virtually unaffected by both picrotoxin and bicuculline.

Action and localization of gamma‐aminobutyric acid in the cat retina.

“…Kirby & Schweitzer-Tong (1981) reported that intravenous injection of GABA antagonists changes the receptive field centre size in Y cells; in an earlier study, it was also reported that X-cell responses remain virtually unaffected by GABA antagonists (Kirby & Enroth-Cugell, 1976). In the present study, we measured area-response curves of the receptive field centre mechanism for two brisksustained(X) cells.…”

“…During bicuculline this maintained firing level was reduced. Centre and surround stimulation Kirby & Enroth-Cugell (1976) reported that GABA antagonists change the balance of Y-cell receptive fields causing the centre response to become more dominant. In the course of the present study, we occasionally found data which apparently supported this claim, as exemplified by the off-centre brisk-transient(Y) cell shown in Fig.…”

“…However, the published results are conflicting because whilst some studies have used in vivo systemic application (Kirby & Enroth-Cugell, 1976;Kirby & Schweitzer-Tong, 1981), others have recorded from the isolated eyecup applying the drugs to the bathing medium (Saito, 1981), while still others applied GABA iontophoretically (Straschill & Perwein, 1969;Ikeda & Sheardown, 1983). Straschill & Perwein (1969), found all ganglion cells to be suppressed by iontophoretic…”

Glycine receptor subunits -a2 and a3 participate in different inhibitory circuits that alter the receptive field organization of on- and off-center retinal ganglion cells.

“…Similar effects of strychnine were reported for a variety of species that include an overall increase in the spontaneous and evoked activity ofRGCs when glycinergic transmission is blocked (Burkhardt, 1972, Kirby and Enroth-Cugell, 1976, Miller and Dacheux, 1977. Caldwell et al (1978) .…”

“…Thus, it is no surprise that the literature is filled with diverse effects of strychnine in the vertebrate retina and some are conflicting. First, strychnine has been reported to increase ON-and OFF-center RGC's spontaneous and evoked activity at LA levels (Kirby andEnroth-Cugell, 1976, Miller et aI, 1977;Muller et aI, 1988) and block light responses of OFF-but not ON-center RGCs at DA levels (MUller et aI, 1988 (Kirby, 1977;Saito, 1981). Third, strychnine abolishes the transient (Caldwell and Daw, 1978;Belgum et aI, 1983Belgum et aI, , 1984O'Brien et al, 2003) and sustained (Stone and Pinto, 1992) components ofRGC responses.…”