Synaptically evoked GABA transporter currents in neocortical glia

Area of Science:

• Neuroscience
• Cellular Neuroscience
• Astrocyte Biology

Background:

• Glial cells, particularly astrocytes, play crucial roles in regulating the extracellular environment.
• Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system.
• GABA transporters (GATs) are responsible for clearing GABA from the synaptic cleft, influencing neuronal activity.

Purpose of the Study:

• To investigate the presence, magnitude, and time course of GABA transporter currents in neocortical astrocytes.
• To determine the contribution of specific GAT subtypes to these currents.
• To elucidate the role of glial GATs in synaptic transmission.

Main Methods:

• Electrophysiological characterization of neocortical astrocytes in an in vitro slice preparation.
• Stimulation using a bipolar-tungsten stimulating electrode.
• Application of subtype-specific GAT antagonists (GAT-1, GAT-2/3).

Main Results:

• The majority of astrocytes exhibited long-lasting GABA transporter currents upon stimulation.
• These currents were identified to originate from at least two GAT subtypes: GAT-1 and GAT-2/3.
• Transporter currents displayed slow rise and long decay times, distinct from glutamate transporter currents.

Conclusions:

• Glial GABA transporters in neocortical astrocytes generate significant and long-lasting currents.
• GAT-1 and GAT-2/3 subtypes contribute to these observed currents.
• The distinct time course suggests a prolonged extracellular GABA presence and highlights the functional role of glial GATs in modulating synaptic transmission.