Hippocampal kindling in rats with absence epilepsy resembles amygdaloid kindling.
OBJECTIVE
WAG/Rij and GAERS rats show delays or resistance to secondary generalization of limbic seizures during amygdaloid kindling. In this study, we aimed to evaluate the kindling from a different limbic site, hippocampus, and to compare its effects on spike-and-wave discharges (SWDs) with that of amygdaloid kindling.


METHODS
Recording electrodes were implanted epidurally and a stimulation/recording electrode was implanted into the ventral hippocampus in the WAG/Rij, GAERS and Wistar rats. Animals received kindling stimulation twice daily at their afterdischarge thresholds until they reached stage 5 seizures, or the maximum number of stimulations (50) had been delivered. The EEG was recorded to analyze SWDs and afterdischarge durations.


RESULTS
All Wistar rats reached stage 5 by the 34th stimulation. 4 of 8 WAG/Rij rats and 3 of 6 GAERS rats displayed stage 4/5 seizures (kindling-prone rats); the rest stayed at stage 2 seizures (kindling-resistant rats) even after 50th stimulations. The cumulative duration and number of SWDs decreased in the post-stimulation period after the first stage 2 seizures, whereas these parameters increased after the first stage 3 seizures in the kindling-prone WAG/Rij and GAERS. The peak frequency of SWDs and its harmonics decreased significantly only in the GAERS group after stage 4 seizures.


CONCLUSIONS
Hippocampal kindling resembles amygdaloid kindling in showing a delay of or resistance to secondary seizure generalization, which supported the interaction of thalamo-cortical and limbic circuitry in GAERS and WAG/Rij.
Akman
Ozlem
O
Kocaeli University, School of Medicine, Department of Physiology, Kocaeli, Turkey.
Karson
Ayse
A
Aker
Rezzan Gulhan
RG
Ates
Nurbay
N
Onat
Filiz Yilmaz
FY
D000679:Amygdala / Q000503:physiopathology*; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D001703:Biophysics; D004195:Disease Models, Animal; D004558:Electric Stimulation / Q000009:adverse effects; D004569:Electroencephalography; D004832:Epilepsy, Absence / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology*; D006624:Hippocampus / Q000503:physiopathology*; D007696:Kindling, Neurologic / Q000502:physiology*; D008297:Male; D051381:Rats; D011922:Rats, Mutant Strains; D017208:Rats, Wistar; D018709:Statistics, Nonparametric; D013238:Stereotaxic Techniques; D013997:Time Factors