Astrocytic mGluR5 Regulation of Synaptic Transmission is Activity-Dependent in Adult Rats

Area of Science:

• Neuroscience
• Cellular Neuroscience
• Synaptic Plasticity

Background:

• Astrocytes are glial cells crucial for regulating synaptic transmission and plasticity.
• In juvenile rats, astrocytes detect glutamate release via mGluR5 receptors and enhance excitatory transmission through purine release.
• It remains unclear if this astrocyte-mediated regulation persists in adult brains.

Purpose of the Study:

• To investigate whether the astrocyte-mediated upregulation of excitatory synaptic transmission observed in juvenile rats is also present in adult rats.
• To explore how astrocyte responses are modulated by different levels of network activity in adult brains.

Main Methods:

• Immunohistochemistry and RNAscope on fixed tissue from adult male rats.
• Electrophysiological recordings from acute hippocampal brain slices of adult male rats.

Main Results:

• The astrocyte-mediated upregulation of excitatory synaptic transmission, triggered by glutamate release and mediated by mGluR5 and purines, was confirmed in adult rats.
• This facilitatory effect was abolished when a large number of inputs were stimulated, unlike when only a few synapses were activated.
• Astrocytes integrate afferent information and adapt their responses based on network activity levels.

Conclusions:

• The astrocyte-mediated regulatory pathway for synaptic transmission is functional in adult rats.
• Astrocytes exhibit adaptive responses, integrating network activity to modulate synaptic transmission efficacy.
• These findings highlight the dynamic role of astrocytes in information processing within the adult brain circuitry.