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Biomedical subjects

M Vergnes

Publications and source records attributed to M Vergnes.

142 records · Page 8Linked to original sources
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Genetic Absence Epilepsy in Rats from Strasbourg (GAERS).

In Genetic Absence Epilepsy Rats from Strasbourg (GAERS), 100% of the animals present recurrent generalized non-convulsive seizures characterized by bilateral and synchronous spike-and-wave discharges (SWD) accompanied with behavioural arrest, staring and sometimes twitching of the vibrissae. Spontaneous SWD (7-11 cps) start and end abruptly on a normal background EEG at a mean frequency of 1.5 per min. Drugs effective against absence seizures in humans suppress the SWD dose-dependently, whereas drugs specific for convulsive or focal seizures are ineffective. Depth EEG recordings and lesion experiments show that SWD in GAERS depend on cortical and thalamic structures with a possible rhythmic triggering by the lateral thalamus; GABAA and GABAB receptors seem to play a critical role. SWD are genetically determined with an autosomal dominant inheritance. The variable expression of SWD in offspring from GAERS and control reciprocal crosses may be due to the existence of multiple genes.

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Interhemispheric desynchronization of spontaneous spike-wave discharges by corpus callosum transection in rats with petit mal-like epilepsy.

Wistar rats of a strain inbred for spontaneous generalized non-convulsive seizures present EEG spike-wave discharges (SWDs), 7-10 c/sec, occurring about once/min and lasting about 15 sec. They are bilateral and synchronous and can be recorded over the entire neocortex and in the lateral thalamic nuclei. After corpus callosum section, only a few bilateral SWDs persisted. Asymmetrical SWDs were most often recorded: bilateral SWDs starting asynchronously, or unilateral SWDs, which were also seen to alternate abruptly between hemispheres. The thalamic SWDs were always synchronized with the ipsilateral cortical pattern. These findings suggest that while the corpus callosum has a major role in bilateral synchronization of SWD in this model of epilepsy, occasional synchronization may still occur through other pathways after callosal transection.

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PubMedDate not supplied

Calcium-dependent regulation of genetically determined spike and waves by the reticular thalamic nucleus of rats.

The pathophysiologic role of the reticular thalamic nucleus (RT) in rat generalized nonconvulsive epilepsy was investigated in the selected strain GAERS (genetic absence epilepsy rats from Strasbourg). After the RT was lesioned by the excitotoxic agent ibotenic acid stereotaxically injected in previously callosotomized rats, a disruption of ipsilateral spike and wave discharges (SWD) was observed in freely moving animals. In a second group of animals Cd2+ (0.5-1.5 microliter, 1 mM), which is known to block Ca2+ and Ca(2+)-dependent K+ conductances (gK+ (Ca2+)), was injected into the thalamus. Cd2+ reversibly suppressed ipsilateral SWD when injected in RT, whereas it slightly reduced SWD expression when injected in the ventrobasal (VB) complex. The difference was highly significant. We conclude that Ca(2+)-dependent oscillatory properties of the RT are critical for expression of genetically determined SWD in GAERS.

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