Structural Features of Neuro-Glio-Vascular Ensembles in the Glomeruli of the Rat Olfactory Bulb

Abstract

The glomeruli of the olfactory bulb of mammals are the primary coding elements of olfactory information. The excitation pattern produced by individual glomeruli in response to olfactory stimulation is stable and specific to certain odors. First of all, this is due to the structure of the neural circuits of the olfactory bulb. Nevertheless, there is reason to believe that auxiliary cells of the nervous system—astrocytes—play a role in the organization of the primary processing of the olfactory signal. It is known that astrocytes not only have a direct effect on synaptic activity and plasticity, but coordinate the joint work of neuronal circuits and the vascular component, forming so-called “neuro-glio-vascular ensembles” as well. In this study, we carried out a morphological study of peripheral processes and gap junctions of astrocytes in order to study the structure of neuro-glio-vascular ensembles at the level of organization of the olfactory bulb glomeruli neuropil. The study showed that the main part of the astrocytic processes inside the glomeruli is located in the area of dendro-dendritic connections of the interneurons and projection neurons of the olfactory bulb, while in the zone of the primary switching of the olfactory signal, the astrocytic processes are practically absent. We also found a pronounced imbalance in the expression of the main astroglial connexins between the different functional poles of the neuro-glio-vascular ensembles of the olfactory bulb and the presence of heterotypic contacts formed by Cx30. The functional significance of the observed features of connexins expression in the olfactory bulb has yet to be studied.