TY - JOUR TI - Similar GABAA receptor subunit composition in somatic and axon initial segment synapses of hippocampal pyramidal cells AU - Kerti-Szigeti, Katalin AU - Nusser, Zoltan A2 - Bartos, Marlene VL - 5 PY - 2016 DA - 2016/08/18 SP - e18426 C1 - eLife 2016;5:e18426 DO - 10.7554/eLife.18426 UR - https://doi.org/10.7554/eLife.18426 AB - Hippocampal pyramidal cells (PCs) express many GABAAR subunit types and receive GABAergic inputs from distinct interneurons. Previous experiments revealed input-specific differences in α1 and α2 subunit densities in perisomatic synapses, suggesting distinct IPSC decay kinetics. However, IPSC decays evoked by axo-axonic, parvalbumin- or cholecystokinin-expressing basket cells were found to be similar. Using replica immunogold labeling, here we show that all CA1 PC somatic and AIS synapses contain the α1, α2, β1, β2, β3 and γ2 subunits. In CA3 PCs, 90% of the perisomatic synapses are immunopositive for the α1 subunit and all synapses are positive for the remaining five subunits. Somatic synapses form unimodal distributions based on their immunoreactivity for these subunits. The α2 subunit densities in somatic synapses facing Cav2.1 (i.e. parvalbumin) or Cav2.2 (cholecystokinin) positive presynaptic active zones are comparable. We conclude that perisomatic synapses made by three distinct interneuron types have similar GABAA receptor subunit content. KW - replica labeling KW - immunohistochemistry KW - GABA KW - inhibition KW - hippocampus JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -