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Fishes are an attractive animal model for investigation of the embryonal and postembryonal central nervous system development and participation in this processes some neurochemical agents. Pacific salmons Oncorhynchus masou, sturgeons Acipencer schrenckii and carps Cyprinus carpio were the objects of our investigation. The purpose of our investigation is to explore the participation of some neurotransmitters (dopamine, GABA), gasotransmitters (NO and H2S) and transcription factor Pax6 in the processes of post-embryonic neurogenesis in fish. In this work, we used methods of immunohistochemical labeling tyrosine hydroxylase, GABA, neuronal NOS, cystathionine β-synthase, transcription factor Pax6, PCNA. The area, which contained apoptosis have been diagnosed by TUNEL-labeling. Results of our research were established, that population of undifferentiated cells, which producing a OH, NOS, Pax6 on the territory of the matrix areas, containing proliferative PCNA-ir cells in the young O. masou 3-, 6-months and 1 year old was founded. The expression of Pax6 in the zones of proliferation, differentiation and migration in the brain integrative centers of adult carp and colocalization of Pax6, TH and CBS in the matrix zone of the brainstem, cerebellum and of lobus vagi. We argue that in periventricular proliferative zones identified expression tyrosine hydroxylase, GABA, NO and H2S, participating in the regulation of the basic histogenetic processes as morphogenetic factors, carrying out paracrinic and autocrinic regulation of cells-predecessors proliferation, migration of differentiating neurons and the expression of specific genes and synthesis.

Teleost fishes are distinct from the mammals in their ability of persistent neurogenesis in the adult brain. Among different contributing factors, Hydrogen sulfide (H 2 S) acts as a novel neuro-modulator and neuroprotective agent, but its role in regulating neurogenesis in the teleost fish remains largely unexplored. To address this issue, we isolated cells from the brain and spinal cord of the two species of salmonid fish, viz., masu salmon ( Oncorhynchus masou ) and trout ( Oncorhynchus mykiss ), cultured them in specially coated duplex dishes with L-15 medium supplemented with 10% fetal bovine serum and examined their proliferation and differentiation properties in vitro . After 3–4 days in culture, neurospheres developed that grew in suspension and reached diameters of up to 80–100 μm within 5–7 days. The cells in suspension further gave rise to both proliferating (PCNA positive) and differentiated neuronal (positive for CBS, Pax6, Hu-C/D, and paravalbumin) cells. The CBS immunoreactivity was observed as a function of H 2 S in cells from both the brain and spinal cord. In masu brain, 66% of the cells were in monolayer and prone to the formation of conglomerates, while, 30.5% of the cells (with 20–40 μm) expressed CBS in spinal cord of the trout. However, small PCNA-positive cells of 10–15 μm diameter predominated and constituted about 38.9% of the CBS positive cells in monolayer. The data suggests involvement of H 2 S-dependent mechanisms in proliferation and differentiation of parenchymal cells and projects primary culture of salmonid’s brain as a powerful tool to study neurogenesis and regeneration in the central nervous system of the adult fish.