Effect of Reversible Inhibition of Hippocampal CAl Region by Lidocaine on Amygdala Kindled Seizures in Rats

In this study the role of CAl region ofdorsal hippocampus on amygdaloid kindled seizures was investigated by bilateral microinjection of lidocaine into the hippocampus.All animals were implanted with a tripolar electrode into the basolateral amygdala and 2 guide cannulae into the CAl region ofthe hippocampus ofthe both hemispheres. Animals were kindled by daily electrical stimulation of the amygdala, then divided into six groups. In groups 1-3, 1% lidocaine was infused into the hippocampus (1 1/2min) and animals were stimulated at 5, 15 and 30 min after the injection and seizure parameters were measured. In groups 4-6, 2% lidocaine was infused into the hippocampus (1  1/2min) and the seizure parameters were measured by the same manner as in groups 1-3. In all groups, 24h before lidocaine injection, saline was injected (I f.J 1/2min) and the parameters were recorded as control. Results showed that afterdischarge duration was reduced at 5 min after the lidocaine (1% and 2%) injection. The stage 5 seizure duration was also decreased at 5 and 15 min after the 2% lidocaine injection. Thus, it may be suggested that in the amygdala kindling, the activity ofneurons ofthe hippocampal CAl region has a role in the spreading of seizure spikes from the amygdala to the other brain region(s) and reduction ofthis activity results in the decrease of seizure severity.