Effect of Glycinergic Blockade on Light Responses of Frog Retinal Ganglion Cells

Abstract

The effect of glycinergic blockade by strychnine on light responses of ganglion cells (GC) was investigated in perfused dark adapted eyecups of frog ( Rana ridibunda). We found that 78% of successfully registered GCs were strychnine-sensitive, but the blocker's effect differed among various cells. In the half of the strychnine-sensitive ON-OFF GCs strychnine markedly potentiated in nearly equal degree their ON and OFF responses, but in a few cases potentiation of only the OFF responses was observed. In three cells, instead of potentiation, diminution of both the ON and OFF responses of ON-OFF GCs was obtained. In some cases the glycinergic blockade changed the apparent cell's type and among these cells it was interesting to observe an opposite effect of the glycinergic blockade on the ON and OFF responses. In contrast to the diverse effects on the ganglion cells' activity, strychnine had one and the same potentiating effect on the amplitude of both b- and d-wave of the local ERG. Our results indicate that the glycinergic interneurons are involved in different networks in the inner plexiform layer of frog retina.