Gaba transporter GATminus1-possitive (GATminus1plus) puncta may play an active role in modulating GABA actions in the trained barrel cortex

We have shown previously that classical conditioning training involving stimulation of a row of facial vibrissae (conditioning stimulus, CS) and electrical shock (unconditioned stimulus, UCS) to the tail is associated with increase in the numerical density of GAD67+ boutons located on the cognate barrel hollows. The present study was designed to determine whether the expression of GABA transporter GAT-1 changes after associative learning using the mice classical conditioning training as a model. We found that numerical density of GABA transporter GAT-1+ puncta was increased by about 50% in the neuropil of the ”trained barrel” hollow compared with controls: pseudoconditioned, whisker stimulation without UCS, and naive group of mice. The electron microscopic observations confi rm that immunoreactivity for GAT-1+ puncta was localized: in single synaptic terminals present on symmetric specialization synapses, on double-synapse spines on symmetric synapse, and on astrocytic processes. The projection of several confocal plans (3D spatial organization) identifi ed GAT-1+ coupled astrocytes. The present evidence supports the hypothesis that GABA transporter GAT-1 localized on GABAergic terminals and the astrocyte networks in the hollow of the “trained barrel” may be involved in learning-dependent changes in layer IV of the barrel cortex. Supported by MNiSW grant 188 to ES.