THE EFFECT OF ACPD ON THE RESPONSES TO NMDA AND AMPA VARIES WITH LAYER IN SLICES OF RAT VISUAL-CORTEX

The effect of 1 S,3 R-aminocyclopentane dicarboxylic acid (ACPD) was m easured on cells from various layers in slices of the rat visual corte x using whole-cell recording techniques. The position of the recorded cell was estimated by distance from pia to the layer VI/white matter b oundary, and verified in 34/97 cells by staining with biocytin. Potent iation or depression of the responses to NMDA and AMPA by the metabotr opic glutamate agonist ACPD was examined by iontophoresis of the drugs close to the cell body. Iontophoresis of ACPD had different effects i n different layers. In layer VI, ACPD produced a substantial depolariz ation, which augmented the responses to NMDA and AMPA. In layer V, ACP D did not produce a significant depolarization, but potentiated the re sponse to NMDA and AMPA. In layer IV, ACPD produced a small hyperpolar ization, and depressed the response to NMDA. In layers II and III, the results were small and variable. Most recordings from stained cells w ere from pyramidal cells. Where recordings from non-pyramidal cells we re obtained (3/34), results were the same as from pyramidal cells in t he same layer. The same results were obtained when tetrodotoxin was in the bath solution. We conclude that the potentiation or depression of the response to NMDA and AMPA by ACPD varies with layer in rat visual cortex. (C) 1998 Elsevier Science B.V. All rights reserved.