[Gaseous intermediates in the brain of the salmon Oncorhynchus masou]

Distribution of nitroxidergic and H2S-producing neurons in the brain of the salmon Oncorhynchus masou was studied by methods of histochemical markering of NADPH-diaphorase and by immunohistochemical markering of the neuronal nitric oxide synthase and cystathionin beta-synthase (CBS). The established distribution of CBS and nNOS/NADPH-d of neurons and fibers in the salmon telencephalon, optic tectum, and cerebellum allows suggesting that the NO- and H2S-producing systems, represent individual, non-overlapping neuronal complexes performing specialized functions in the activity of local neuronal networks. In the brainstem part, the nNOS-ir and NADPH-d-positive neurons were detected in the composition of viscerosensor (V, VII, and IX-X) and visceromotor (III, IV, and VI) nuclei of craniocerebral nerves, octavolateral afferent complex, reticulospinal neurons, and medial reticular formation. CBS in the salmon medulla was revealed in neurons of the X nerve nucleus, reticulospinal neurons, and ventrolateral reticular formation. Distribution of NO-ergical and H2S-producing neurons in the salmon medulla nuclei indicates that NO in salmon is the predominant neuromodulator of medulla viscerosensory systems, while H2S seems to modulate only the descending motor systems. The results of the performed study allow suggesting that NI in the descending motor systems. The results of the performed study allow suggesting that NO in the salmon medulla periventricular area can act as a regulator of postnatal ontogenesis.