The role of astrocytic metabotropic glutamate receptor 5 in social behavior

Astrocytes were seen for a long time as supportive cells in the central nervous system. However, evidence points to the pivotal role of these cells in brain function, including the modulation of synaptic transmission. Astrocytes express neurotransmitter receptors at the cellular membrane, whose activation may cause somatic calcium elevations and consequently release signaling molecules in the synaptic cleft. The impact of astrocytic signaling in the modulation of neuronal circuits and behavior is still poorly understood. Social behavior results from a complex interaction between brain regions. It is promoted by a variety of sensory cues, modulated by social internal states such as motivation, emotion, reward, or memory, and lastly affected by decision-making integration. Cortico-limbic regions in the brain are responsible for the integration between cognition and emotion and are crucial for the behavioral output as social behaviors. In those regions where glutamate is the primary fast excitatory neurotransmitter, astrocytes express glutamate receptors, such as the metabotropic glutamate receptor 5 (mGluR5). In this work, we generated a mouse line lacking the mGluR5 in astrocytes and tested social behavior in these mice in an optimized three-chamber sociability and social novelty test. This work provided further information on the involvement of astrocytes in different forms of behavior.