Structural plasticity of synapses in hippocampal slices after oxygen-glucose deprivation

We analyzed structural rearrangements of synaptic contacts in the stratum radiatum of the CA1 area of cultured rat hippocampal slices under conditions of the development of potentiation of synaptic transmission induced by short-term (10 min) oxygen-glucose deprivation (OGD). Studies were carried out using electron microscopy and 3D reconstruction of cellular compartments. Within the 1st h after OGD, we observed increases in the volume of pre-synaptic terminals and post-synaptic spines and also in the area of postsynaptic densities (PSDs) in both asymmetric excitatory and symmetric inhibitory synapses, especially in the case were the PSD was perforated. We also observed significant activation of glial cells (increases in their volume and area of contacts of their processes with the components of synapses). Therefore, OGD results in activationassociated structural rearrangements of both excitatory and inhibitory synapses of the hippocampal CA1 area. Such rearrangements are accompanied by a clearly pronounced reaction of the glia, which correlates with an important role of the latter in modulation of the functioning of neurons.