The effect of strychnine, bicuculline, and picrotoxin on X and Y cells in the cat retina.

Abstract

A B S T a A C T The effect of intravenous strychnine and the GABA antagonists picrotoxin and bicuculline upon the discharge pattern of center-surround-organized cat retinal ganglion cells of X and Y type were studied. Stimuli (mosdy scotopic, and some photopic) were selected such that responses from both on and off-center cells were either due to the center, due to the surround, or clearly mixed. Pre-drug control responses were obtained, and their behavior following administration of the antagonists was observed for periods up to several hours. Xcell responses were affected in a consistent manner by strychnine while being unaffected by GABA antagonists. All observed changes following strychnine were consistent with a shift in center-surround balance of X cells in favor of the center. For Y-cell responses to flashing annuli following strychnine, there was either no shift or a relatively small shift in center-surround balance. Compared to X-cell responses to flashing lights, those of Y cells were very little affected by strychnine and in most cases were unaffected. It thus appears that glycine plays a similar role in receptive field organization of X cells as does GABA in Y cells (Kirby and Enroth-Cugell, 1976.J. Gen. Physiol. 68: 465--484).

Effects of picrotoxin and strychnine on non‐linear responses of Y‐type cat retinal ganglion cells.

“…The concentration in the retina itself must have been lower due to the blood-retinal barrier. These doses are slightly below those calculated by Caldwell, Daw & Wyatt (1978) for their experiments on -rabbits, and are the same as those which have previously been shown to be effective on cat retinal ganglion cells (Kirby & Enroth-Cugell, 1976;Kirby, 1979).…”

“…Under scotopic conditions pictrotoxin affected the linear receptive field components of Y cells (Kirby & Enroth-Cugell, 1976;, while under the mesopic and photopic conditions used here its major effect was on the non-linear responses. Strychnine also has quite different effects under the two conditions, reducing centre sensitivity under mesopic but not scotopic conditions (Kirby, 1979). Differences in pharmacology might be expected on the basis of the differences in the rod and cone pathways at the level of the inner plexiform layer (Kolb & Famiglietti, 1974;Nelson, Famiglietti & Kolb, 1978).…”

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

“…The results from studies using intravenous injection of GABA and bicuculline indicate a difference between X-and Y-type retinal ganglion cells (Kirby & Enroth-Cugell, 1976;Kirby, 1979;Kirby & Schweitzer-Tong, 1981). X cells seem to be unaffected by GABA and its antagonists, Y cells show a difference in the centre surround organization and in the centre size when bicuculline or picrotoxin are injected.…”

Action and localization of glycine and taurine in the cat retina.

“…Later studies on ganglion cells in the cat retina reported more specific effects of systemically applied strychnine. Chu (1968) found that the inhibition of off-centre but not of on-centre ganglion cells was blocked by strychnine, whereas Kirby (1979) found effects of strychnine only on brisk-sustained(X) cells but not on brisk-transient(Y) cells, irrespective of whether the cells were on-or off-centre ganglion cells. Using an isolated eyecup preparation Saito (1981) reported that the surround inhibition of on-centre brisk-sustained(X) cells was blocked by strychnine, whereas the surround inhibition of other ganglion cell types was unaffected by strychnine.…”