Blockade of high frequency rhythmical slow activity by intrahippocampal injection of a glutamic acid antagonist.

Intrahippocampal injections of glutamic acid diethylester (GDEE) were performed in rats in order to study a possible implication of glutamate in the mediation of high frequency (8-12 Hz) rhythmical slow activity (RSA) elicited by 100 Hz electrical stimulation of the dorsomedial hypothalamus. This 8-12 Hz RSA was selectively and reversibly suppressed in hippocampal EEG 6 min and 15 min after 150 micrograms or 400 micrograms of GDEE, whereas no modifications were found in the low frequency RSA (6-8 Hz) evoked in hippocampus during exploratory behavior.