Nitroxidergic and Calretinin-Containing Nonpyramidal Neurons of Rat Hippocampus

Abstract—: Unlike pyramidal neurons, interneurons of the hippocampus are a heterogeneous group of neurons that differ in their morphological, cytochemical, and functional characteristics. The aim of this study was to conduct a comparative morphological analysis of nitroxidergic (NOS+) and calretinin-containing (CR+) nonpyramidal neurons of the CA1 and CA3 zones in the rat hippocampus using immunohistochemical methods. Qualitative and quantitative differences in NOS+ and CR+ populations of nonpyramidal neurons in different layers of the studied zones of the hippocampus were demonstrated. Differences in the quantitative composition of the studied populations of interneurons were also demonstrated in two subregions of the hippocampus that correspond to dorsal and intermediate hippocampus. It was established that NOS+ interneurons are more typical for the dorsal hippocampus, while a greater number of CR+ interneurons are presented in the intermediate hippocampus. Data obtained during the study can contribute to understanding the role of nonpyramidal neurons in the formation of functional specialization of different regions of the hippocampus. © 2022, Pleiades Publishing, Ltd.