GAERS

EEG décharges de pointe-ondes

Genetic Absence Epilepsy Rats from Strasbourg (GAERS) are a strain of laboratory rats that serve as an animal model for human absence epilepsy. GAERS exhibit spontaneous absence seizures, which are characterized by sudden, brief lapses in consciousness accompanied by a cessation of activity, a hallmark of this type of epilepsy. The GAERS model has been instrumental in the study of the genetic, neurobiological, and pharmacological aspects of absence epilepsy, providing insights into potential therapeutic targets and mechanisms underlying this condition.

Characteristics

GAERS are identified by their distinctive phenotype of absence seizures, which typically begin to manifest around the age of 2 to 3 months. These seizures are characterized by the presence of spike-and-wave discharges (SWDs) on the electroencephalogram (EEG), which are indicative of the generalized, non-convulsive seizures seen in absence epilepsy. The frequency and duration of these SWDs can vary, but they are a consistent feature in the EEG recordings of GAERS.

Genetic Basis

The genetic basis of absence epilepsy in GAERS is complex and involves multiple genes. Research has identified several genetic loci that contribute to the susceptibility of GAERS to develop absence seizures. These findings suggest that the genetic architecture of absence epilepsy in GAERS involves both major effect genes and modifier genes, which may interact with environmental factors to influence the phenotype.

Neurobiological Mechanisms

Studies on GAERS have revealed alterations in various neurotransmitter systems and ion channels that are implicated in the generation of SWDs and absence seizures. These include changes in GABAergic inhibition, T-type calcium channels, and glutamate receptor signaling. The thalamocortical circuitry, which connects the thalamus with the cortex, plays a crucial role in the generation of SWDs in GAERS. Abnormalities in the function of this circuitry are thought to underlie the pathophysiology of absence seizures.

Pharmacological Studies

GAERS have been used extensively in pharmacological studies to test the efficacy of anti-epileptic drugs (AEDs) for absence epilepsy. These studies have shown that drugs which reduce T-type calcium channel activity, such as ethosuximide and valproate, are effective in suppressing SWDs in GAERS. Conversely, drugs that are ineffective against absence seizures, or that may exacerbate them, have also been identified through research on GAERS. This has helped in refining the treatment strategies for absence epilepsy in humans.

Conclusion

The GAERS model has significantly advanced our understanding of absence epilepsy, from its genetic underpinnings to the neurobiological mechanisms and pharmacological treatment options. As research continues, GAERS will remain a vital tool in the quest to uncover the complexities of absence epilepsy and to develop more effective therapies for those affected by this condition.