The Phenomenon of Compensatory Cell Proliferation in Olfactory Epithelium in Fish Caused by Prolonged Exposure to Natural Odorants

Igor V Klimenkov,Nikolay P Sudakov,Nikolay S Kositsyn,Mikhail V Pastukhov

doi:10.1038/s41598-020-65854-9

Igor V Klimenkov, Nikolay P Sudakov + Show 2 more

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https://doi.org/10.1038/s41598-020-65854-9

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Abstract

It was previously shown that activation of the processes of neurogenesis in the olfactory epithelium (OE) can be caused after intranasal administration of toxic or neurotrophic factors, after axon transection, or as a result of bulbectomy. Our study showed for the first time that a significant increase in olfactory cell renewal can also occur in animals due to periodic chemostimulation with natural odorants (amino acids and peptides) for 15 days. Using electron and laser confocal microscopy in fish (Paracottus knerii (Cottidae), Dybowski, 1874) from Lake Baikal, we showed that periodic stimulation of aquatic organisms with a water-soluble mixture of amino acids and peptides causes stress in OE, which leads to programmed death cells and compensatory intensification of their renewal. We estimated the level of reactive oxygen species, number of functionally active mitochondria, intensity of apoptosis processes, and mitosis activity of cells in the OE of fish in the control group and after periodic natural odorants exposure. This study showed that new stem cells are activated during enhanced odor stimulation and subsequent degenerative changes in the cells of the sensory apparatus. Those new activated stem cells are located in previously proliferatively inactive regions of OE that become involved in compensatory processes for the formation of new cells.

Highlights

In this publication we present a new approach for stimulating of cell proliferation in olfactory epithelium (OE), which allows one to avoid these complications
It was established that, compared with that of the control (Fig. 1C), the OEs of the experimental fish, which were subjected to intensive odorant exposure to a mixture of amino acids and peptides, showed signs of densification and fragmentation of nuclei in epithelial cellular elements, which serve as an indicator of the final phase of PCD43
The plot shows that the volume occupied by the mitochondria decreased by a factor of 6.2 between the experimental and control fish

Summary

Introduction

In this publication we present a new approach for stimulating of cell proliferation in OE, which allows one to avoid these complications. In order to activate this processes, we proceeded from the two main facts: (1) amino www.nature.com/scientificreports acids (and, to a lesser extent, peptides) and their mixtures are effective natural odorants for fishes[22,23,24,25,26,27], and (2) OSNs are monospecific[28,29,30], which is why we used a mixture of such structurally diverse molecules to increase the number of odorant-stimulated OSNs. We applied a long (15 days) periodic (12 hours every day) exposure of OE in fish to mixture of a wide range of natural water-soluble odors (amino acids and peptides). This effect caused stress in a large amount of OSN, which was accompanied by degenerative changes in the mitochondria and activation of programmed cell death (PCD), which led to a compensatory increase in the activity of mitotic stem cells (SC) in OE

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