ABSTRACT
The distribution of proliferative zones, NO-producing cells and apoptosis areas in the medulla oblongata, cerebellum, optic tectum, thalamus and hypothalamus of Amur sturgeon Acipenser schrenckii was investigated, using techniques of immunoperoxidase staining of proliferating cell nuclear antigen (PCNA), neuronal nitric oxide synthase and TU-NEL-labeling of fragmented DNA. It has been established, that in the sturgeon brain NO can act both as a cytotoxic proapoptogenic factor, and as a factor, which stimulates cell proliferation. The presence of NO-producing elements in somato- and viscerosensory areas of medulla oblongata, tectum, cerebellum and thalamus suppose, that in these brain areas NO constitutes apoptogenic factor, which induces the cells death in a territory of postmitotic neuroblasts, renders controlling effect on development and differentiating of chemosensory, visual, motor and hypophysotropic brain areas in postnatal ontogenesis. Maximal proliferating activity and high concentration of NO-ergic cells were revealed in external layers, adjoining to the medullar, cerebellar and tectum membranes, that allow to suppose NO participation in postnatal morphogenesis of these brain structures as a factor, which regulates cell proliferation. In sensory centers (tectum and nuclei of the V, VII, and X nerves), significantly varying ratios of intensities of proliferation and apoptosis were found; this is indicative of dissimilar rates of growth and differentiation in visual and chemosensory centers of the sturgeon brain. Presence of NO-producing elements in the PCNA- immuno-labeling and TUNEL-labeling brain areas allow to consider NO as a factor, which balances processes of proliferation and apoptosis in the sturgeon brain.