Inhibitory effect of state independent ponto-geniculo-occipital waves on seizure occurrence induced by local application of penicillin into the temporal lobe amygdala.

Abstract

PURPOSE: In order to explore the possible inhibitory role of the phasic phenomena of REM sleep ponto-geniculo-occipital (PGO) waves over epilepsy, seizure activity produced by topic administration of Na-penicillin (PCN) has been analyzed during sustained PGO waves irrespective of current state. PGO waves were induced by the injection of carbachol in the peribrachial area. METHODS: The development of acute experimental epilepsy was compared among nine chronically implanted, adult, male cats, by means of polygraphic 23 h recordings. Our protocol consisted of sets of 4 trials: carbachol; PCN; carbachol followed by PCN and finally PCN followed by carbachol. Each cat received one single set and all trials were carried out with a seven days interval, in order to compare the epileptic activity both in the presence of PGOs and without them. RESULTS: PGO waves 1) exert an inhibitory influence over number and duration of the Generalized Convulsive Seizures (GCSs) and 2) spike frequency; 3) increase the latency of GCSs; and 4) restores sleep alterations produced by experimental epilepsy. CONCLUSIONS: PGO waves exhibit an inhibitory influence over seizures induced by PCN. These data support the hypothesis that this phasic phenomenon of REM sleep have a depressant effect on epilepsy, inhibit seizures and normalize sleep architecture changes induced by seizures. We suggest that one possible function of PGO activity is to protect the brain from intense changes in neuronal excitability; namely convulsive activity.