Excitatory effect of intrahippocampal injection of glutamic acid on rabbit EEG.

Glutamic acid microinjection into the rabbit dorsal hippocampus was studied in its effects on hippocampal and cortical electroencephalogram (EEG). The studies were carried out on rabbits with chronically implanted electrodes and cannulae. Bipolar, silver recording electrodes and stainless steel cannulae were implanted into the hippocampus, and recording electrodes were placed on the surface of the frontal and cingular cortical areas. Low doses of glutamic acid (5-25 nM) induced EEG and behavioral arousal. Short lasting epileptiform-like seizures and behavioral convulsions were induced after injection of high doses of glutamic acid (100-500 nM). These findings suggest that glutamic acid in the hippocampus of the rabbit is involved in behavioral arousal and epileptiform-like disorders.