Influence of transcranial magnetic stimulation on spike-wave discharges in a genetic model of absence epilepsy.

Transcranial magnetic stimulation (TMS) impulses, (0.5 Hz, 3 impulses) were presented at threshold intensity to male WAG/Rij rats. One group received stimuli, which involved motor responses of hindlimbs, rats of the second group received sham stimulation.

Are there different mechanisms of synchronization in the course of spike-wave discharges (SWDs) burst development in WAG/Rij rats?

In WAG/Rij rats the pair linear correlation r was calculated for bipolar recordings in fronto-temporal, fronto-occipital and occipito-temporal zones of both hemispheres as well as in paleocerebellar cortex (culmen). It was shown that development of SWD bursts resulted in interhemispheric decreases of correlation between the right occipito-temporal cortical region on one side, and left fronto-temporal on the contralateral side. Towards the end of SWD, we found an increased interhemispheric correlation between left fronto-temporal and right fronto-occipital cortical zones, as well as, between both fronto-temporal zones.

The brain 5HTergic response to an acute sound stress in rats with generalized (absence and audiogenic) epilepsy.

The brain serotoninergic (5HTergic) system of epileptic subjects can influence their vulnerability to stress. We studied the putative dependency of 5HT neurotransmission parameters on emotional stress, and the presence, types and severity of seizures using rats with genetic generalized (absence and/or audiogenic) epilepsy, of WAG/Rij and Wistar strains. The animals were stressed by exposure to a short aversive noise or left without sound stimulation.

Measuring clusters of spontaneous spike-wave discharges in absence epileptic rats.

Spike-wave discharges (SWDs) characterizing absence epilepsy appear in closely packed aggregated sequences, which gave rise to the name "pyknolepsy" for this disease. In WAG/Rij rats, genetically prone to absence epilepsy, spontaneous SWDs seem to occur in clusters as well. Here, we aimed to quantify the seizures' clusters.

The preferential mGlu2/3 receptor antagonist, LY341495, reduces the frequency of spike-wave discharges in the WAG/Rij rat model of absence epilepsy.

We examined the expression and function of group-II metabotropic glutamate (mGlu) receptors in an animal model of absence seizures using genetically epileptic WAG/Rij rats, which develop spontaneous non-convulsive seizures after 2-3 months of age. Six-month-old WAG/Rij rats showed an increased expression of mGlu2/3 receptors in the ventrolateral regions of the somatosensory cortex, ventrobasal thalamic nuclei, and hippocampus, but not in the reticular thalamic nucleus and in the corpus striatum, as assessed by immunohistochemistry and Western blotting. In contrast, mGlu2/3 receptor signalling was reduced in slices prepared from the somatosensory cortex of 6-month-old WAG/Rij rats, as assessed by the ability of the agonist, LY379268, to inhibit forskolin-stimulated cAMP formation.