Destruction of the indoleamine-accumulating amacrine cells alters the ERG of rabbits.

The indoleamine-accumulating amacrine cells in the rabbit's retina were destroyed by intravitreal injections of 5,7-DHT according to the technique of Ehinger and Florén. One week after the injections, histofluoresence microscopy failed to show the IA-cells in the retina. At this time, the b-wave of the treated eyes was significantly smaller, the OPs were more prominent, and the duration of the b-wave was longer. The a- and c-waves and the off-response were not affected. The loss of the IA-cells resulted in a reduction in the range of dark-adaptation but did not affect the rate of recovery of the threshold. The loss of the IA-cells also had no effect on the response of the retina to flickering light. In a double-flash experiment, the suppression of the response to the second flash was significantly weaker in the treated eyes. These results can be explained by the loss of a negative feedback circuit that has been proposed for the IA-cells from morphologic studies.