Sequential treatment with low doses of kainic acid alters sensitivity of retinal cell types

Examination of chick retinae soon after treatment with a single intraocular injection of 5 nmol kainic acid revealed degenerative changes in a small population of neurons located in the outer aspect of the inner nuclear layer, consistent with either bipolar and/or horizontal cells. Damage to the outer plexiform layer was also present. After one week, affected retinae were clear of neuronal debris. Following a second, identical injection, one week after the first, there was degeneration of a different population of neurons confined to the inner aspect of the inner nuclear layer indicative of amacrine cells. As amacrine cells were the only cell type affected by the second injection, our results suggest that they are directly affected by the second dose of kainic acid. The pattern of neuronal damage following successive doses of kainic acid appears to be potentially useful technique in elucidating retinal circuitry.