The role of GABAA receptor activity in post-ictal depression period ‎in a rat kindling model of epilepsy ‎

Following the seizure there is an inhibitory period named “post-ictal depression period” which has a depressing effect on the following seizure. In this study, the role of GABAA receptors on post-ictal depression period was investigated in amygdala kindling model of epilepsy in rat. Animals were kindled by electrical stimulation of amygdala. Then, they were divided into four groups. Different groups of kindled animals were received a second stimulation at 10, 30, 60 and 90 min after the first stimulation and the percentage of suppression of seizure parameters after the second stimulation was calculated. In another four groups, bicucullin, a selective GABAA receptor antagonist (100 nM), was intra-cerebroventricularly microinjected 10 min before the second stimulation and its effect on the percentage of suppression induced by the first stimulation was investigated. Six animals were used in each group. When the second stimulation was applied at 10 and 30 min after the first stimulation a significant reduction was observed in the seizure severity and seizure parameters were depressed after the second stimulation. Bicucullin microinjection significantly decreased the percentage of depression in seizure parameters following the second stimulation compared to the animals received the solvent alone (P<0.05). This decrease was significant when the second stimulation was applied at 10 and 30 min after the first stimulation. Obtained results showed that activity of GABAA receptors by endogenous GABA is one of the mechanisms involved in post-ictal depressing period. However, the blocking of these receptors could not completely prevent this period. Thus, other factors have also role in its induction