3D Ultrastructure of Synaptic Inputs to Distinct GABAergic Neurons in the Mouse Primary Visual Cortex

Synapses are the fundamental elements of the brain’s complicated neural networks. Although the ultrastructure of synapses has been extensively studied, the difference in how synaptic inputs are organized onto distinct neuronal types is not yet fully understood. Here, we examined the cell-type-specific ultrastructure of proximal processes from the soma of parvalbumin-positive (PV+) and somatostatin-positive (SST+) GABAergic neurons in comparison with a pyramidal neuron in the mouse primary visual cortex (V1), using serial block-face scanning electron microscopy. Interestingly, each type of neuron organizes excitatory and inhibitory synapses in a unique way. First, we found that a subset of SST+ neurons are spiny, having spines on both soma and dendrites. Each of those spines has a highly complicated structure that has up to eight synaptic inputs. Next, the PV+ and SST+ neurons receive more robust excitatory inputs to their perisoma than does the pyramidal neuron. Notably, excitatory synapses on GABAergic neurons were often multiple-synapse boutons, making another synapse on distal dendrites. On the other hand, inhibitory synapses near the soma were often single-targeting multiple boutons. Collectively, our data demonstrate that synaptic inputs near the soma are differentially organized across cell types and form a network that balances inhibition and excitation in the V1.

ULTRASTRUCTURE OF SYNAPSES IN THE HIPPOCAMPUS OF RATS IN AGING

The aim of the study was to examine age-related changes in the ultrastructure of synapses in the CA1 region of the hippocampus of Wistar rats and premature aging OXYS rats.To assess changes of the sinaptoarhitectonics photographed on 15 randomly chosen fields of view of the pyramidal layer of the CA1 region of the hippocampus with five slices at a standard magnification of 10000. It was determined the amount of mineral contacts (size of the field of view is 50 μm2) and calculated numerical density of synapses per 100 μm2. The number of contacts with asymmetric and symmetric organization sistemasubsidiaries units, perforated, hypertrophic contacts are counted.The study showed that there are significant differences in the ultrastructural organization of the synapses between the lines, already 4 months old. The numerical density of snaps in this age group OXYS rats was significantly higher than that of Wistar. Ultrastructure of synapses in the CA1 region of the hippocampus of rats at the age of 18 months more bulupodadan pathological essentiaompetencies processes and membrane prematurely senescent rats in contrast to the control line. The numerical indicator of protect contents 18-month-old rats OXYS was significantly lower than in Wistar.Identified interstrain differences in the degree of changes of synapses can testify in favor of a different sensitivity to oxidative stress in rats investigated lines.