Studying the properties of neural stem progenitor cells (NSPCs) in a fish model will provide new information about the organization of neurogenic niches containing embryonic and adult neural stem cells, reflecting their development, origin cell lines and proliferative dynamics. Currently, the molecular signatures of these populations in homeostasis and repair in the vertebrate forebrain are being intensively studied. Outside the telencephalon, the regenerative plasticity of NSPCs and their biological significance have not yet been practically studied. The impressive capacity of juvenile salmon to regenerate brain suggests that most NSPCs are likely multipotent, as they are capable of replacing virtually all cell lineages lost during injury, including neuroepithelial cells, radial glia, oligodendrocytes, and neurons. However, the unique regenerative profile of individual cell phenotypes in the diverse niches of brain stem cells remains unclear. Various types of neuronal precursors, as previously shown, are contained in sufficient numbers in different parts of the brain in juvenile Pacific salmon. This review article aims to provide an update on NSPCs in the brain of common models of zebrafish and other fish species, including Pacific salmon, and the involvement of these cells in homeostatic brain growth as well as reparative processes during the postraumatic period. Additionally, new data are presented on the participation of astrocytic glia in the functioning of neural circuits and animal behavior. Thus, from a molecular aspect, zebrafish radial glia cells are seen to be similar to mammalian astrocytes, and can therefore also be referred to as astroglia. However, a question exists as to if zebrafish astroglia cells interact functionally with neurons, in a similar way to their mammalian counterparts. Future studies of this fish will complement those on rodents and provide important information about the cellular and physiological processes underlying astroglial function that modulate neural activity and behavior in animals.

The review article explores the role of constitutive neurogenesis in the brains of vertebrates, with a special focus on fish as a model organism for studying neurogenesis. In particular, the article discusses the involvement of neuroepithelial stem cells and radial glia in both pre- and postnatal neurogenesis of the central nervous system, alongside the contribution of radial glia to embryonic and adult neurogenesis. Special emphasis is placed on the characteristics of neurogenesis in lower vertebrates, particularly fish, as a promising model for understanding these processes. Using several species of Pacific salmon as subjects, the review also investigates how fetalization influences constitutive and post-traumatic neurogenesis in adult animals. Notably, significant glial plasticity observed in response to mechanical brain injury in Danio rerio L. highlights the importance of tightly regulated balance between quiescence and proliferation in determining regenerative potential. This balance is crucial for maintaining stem cell pools that are responsive to neuronal loss. The article also discusses contemporary findings on the heterogeneity of neural stem cell and radial glia populations. In conclusion, the article presents recent insights into the involvement of glia in neural network functioning and the modulation of behavioral activity. В обзорной статье представлены данные о конститутивном нейрогенезе в мозге позвоночных животных. Обсуждается участие нейроэпителиальных стволовых клеток и радиальной глии в пре- и постнатальном нейрогенезе ЦНС, а также вклад радиальной глии в эмбриональный и взрослый нейрогенез. Особое внимание в обзоре уделяется анализу особенностей нейрогенеза у низших позвоночных животных (рыб) как перспективной модели для исследования этих процессов. На нескольких видах тихоокеанских лососей изучено влияние процесса фетализации на конститутивный и посттравматический нейрогенез у взрослых животных. Выявленная значительная глиальная пластичность, возникающая в ответ на механическую травму головного мозга у Danio rerio L., указывает, что жесткая регуляция баланса покоя и пролиферации является определяющим фактором регенеративной активности и способствует поддержанию эффективных пулов стволовых клеток, готовых реагировать на потерю нейронов. Обсуждаются современные аспекты проблемы, связанные с гетерогенностью пулов нейральных стволовых клеток и радиальной глии.