Toll-like Receptor 8 (TLR8) Is Expressed in Mouse Hippocampal Neurons and Modulates Neuronal Excitability

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• Toll-like receptors (TLRs) are crucial for innate immunity.
• Neuronal TLRs influence neuronal development and function.
• The specific role of TLR8 in neurons requires further investigation.

Purpose of the Study:

• To investigate the expression and function of TLR8 in mouse postnatal hippocampal neurons.
• To determine the impact of TLR8 activation on neuronal activity and signaling pathways.

Main Methods:

• Immunocytochemistry to assess TLR8 and TLR7 expression.
• Electrophysiological recordings using a multi-electrode array system.
• Calcium flux imaging and Western blot analysis.
• Pharmacological manipulation with TLR8 agonists and NMDA receptor antagonists.

Main Results:

• TLR8 and TLR7 are expressed in postnatal hippocampal neurons, particularly in GABAergic interneurons.
• TLR8 agonist stimulation increased neuronal activity and synchronization.
• TLR8-induced calcium flux was dependent on NMDA receptor activity.
• Canonical TLR signaling pathway activation (IkB-α degradation) was not observed.

Conclusions:

• TLR8 and TLR7 are expressed in mouse hippocampal neurons.
• TLR8 activation enhances neuronal excitability, potentially via NMDA receptors.
• Acute TLR8 stimulation does not activate the canonical TLR signaling pathway in these neurons.