Microglia modulate TNFα-mediated synaptic plasticity

Area of Science:

• Neuroscience
• Neuroinflammation
• Synaptic Plasticity

Background:

• Tumor necrosis factor α (TNFα) is a pro-inflammatory cytokine that influences neuronal synaptic plasticity.
• The precise mechanisms by which TNFα mediates synaptic positive (change) and negative (stability) feedback remain unclear.

Purpose of the Study:

• To investigate the effects of TNFα on microglia activation and synaptic transmission in mouse organotypic entorhino-hippocampal tissue cultures.
• To elucidate the role of microglia in TNFα-induced synaptic plasticity and homeostasis.

Main Methods:

• Organotypic entorhino-hippocampal slice cultures from mice were used.
• Effects of varying concentrations of TNFα on excitatory and inhibitory neurotransmission were assessed.
• Microglia activation and synaptic changes, including GluA1-containing AMPA receptor accumulation, were analyzed.
• Experiments were conducted in both intact and microglia-depleted cultures.

Main Results:

• TNFα modulated excitatory and inhibitory neurotransmission in a concentration-dependent manner.
• Low TNFα concentrations strengthened glutamatergic transmission; higher concentrations increased inhibition.
• Activated microglia induced homeostatic adjustment of excitatory synapses, returning strength to baseline within 24 hours while increasing inhibition.
• In microglia-depleted cultures, TNFα-induced synaptic strengthening persisted.

Conclusions:

• Microglia play a crucial role in TNFα-mediated synaptic plasticity and homeostasis.
• Pro-inflammatory microglia act as negative feedback regulators, influencing neuronal plasticity and stability.
• Microglia are essential gatekeepers of synaptic change and stability in the brain.