Project Title:

Nature of the GABA transporter GAT1 malfunction in thalamic astrocytes in absence epilepsy

Tatiana Morais

Objectives:

Increased tonic GABA_A receptor inhibition in the thalamus is necessary and sufficient for induction of seizures of experimental absence epilepsy (AE). Drugs that increase GABA levels elicit and aggravate absence seizures (ASs) in normal individuals and in AE patients. Although tonic inhibition results from malfunction of the astroglial GABA transporter GAT1, there are no genetic abnormalities of the GAT1 gene. Here, it will be investigat­ed in situ and in vivo whether thalamic GAT1 malfunction in genetic animal models of AE results from either 1) abnormal phosphorylation, 2) failure of trafficking to the outer astrocytic membrane, and/or 3) misplaced localiz­ation with respect to synaptic or extrasynaptic regions of the GABAergic synapses between thalamic reticular and thalamocortical neurons.

Methodology:

Experiments will involve 3H-GABA uptake, biotinylation experiments and live trafficking of fluorescence-tagged GAT1 in thalamic slices and in cultures of pure thalamic astrocytes) as well as immunogold EM localization of GAT1 transporter, GABA_B and δ-subunit containing GABA_A receptor and in thalamic regions. This work will be carried out in rat and mouse models of absence epilepsy.

Vincenzo Crunelli
Cardiff University