Aminooxyacetic acid causes selective neuronal loss in layer III of the rat medial entorhinal cortex

Aminooxyacetic acid (AOAA) was used to produce a selective lesion in the rat entorhinal cortex (EC). As assessed 7 days following the injection of AOAA (75 micrograms/0.75 microliter) into the EC, neuronal loss in layer III of the medial EC, particularly in its ventral portion, was consistently observed in Nissl-stained horizontal sections. This selective neurodegeneration was seen even when AOAA was injected laterally or in deeper layers. Behavioral seizures occurred between 2 and 4 h after the AOAA injection. AOAA-induced EC lesions may provide experimental models for the study of human diseases in which the EC, particularly layer III neurons, is involved.