Microglia modulate TNFα‐mediated synaptic plasticity

The pro-inflammatory cytokine tumor necrosis factor α (TNFα) tunes the capacity of neurons to express synaptic plasticity. It remains, however, unclear how TNFα mediates synaptic positive (=change) and negative (=stability) feedback mechanisms. We assessed effects of TNFα on microglia activation and synaptic transmission onto CA1 pyramidal neurons of mouse organotypic entorhino–hippocampal tissue cultures. TNFα mediated changes in excitatory and inhibitory neurotransmission in a concentration-dependent manner, where low concentration strengthened glutamatergic neurotransmission via synaptic accumulation of GluA1-only-containing AMPA receptors and higher concentration increased inhibition. The latter induced the synaptic accumulation of GluA1-only-containing AMPA receptors as well. However, activated, pro-inflammatory microglia mediated a homeostatic adjustment of excitatory synapses, that is, an initial increase in excitatory synaptic strength at 3 h returned to baseline within 24 h, wh..., Transcriptome analysis
Tissue cultures (n = 3) were transferred as one sample into 250 μL RNAlater (Thermo Fisher Scientific, Cat# AM7020) and stored at −20°C. RNA was isolated after homogenization with TRIzol (Thermo Fisher Scientific, Cat# 15596018) using the Direct-zol RNA Microprep-Kit (Zymo Research, Freiburg im Breisgau, Germany, Cat# R2061) according to the manufacturer's instructions. RNA was eluted in 50 μL water and precipitated with 0.75 M ammonium-acetate and 10 μg glycogen (Thermo Fisher Scientific, Cat# R0551) by adding 125 μL ethanol (100%). Samples were incubated at −80°C overnight and consecutively centrifuged for 30 min at 4°C. Pellets were washed with 70% ethanol, centrifuged again and dried. Finally, pellets were dissolved in water for further processing. RNA concentration and integrity were consecutively analyzed by capillary electrophoresis using a Fragment Analyzer (Advanced Analytical Technologies, Inc., Ankeny, IA, USA) and the Agilent RNA 6000 Pico Kit (Agilent..., Transcriptome Analysis Console 4.0 (Applied Biosystems).
R-4.3.1, oligo R package, limma R package, GSEA 4.1.0.