Search

We studied the effects of acute normobaric hypoxia on postnatal day 2 (model of preterm pregnancy) on reflex activity and behavior of juvenile male Wistar rats and the possibility of correction of behavioral deficit by administration of GABA derivative Salifen after hypoxia. It is shown, that perinatal hypoxia impaired righting reflex and forelimb grip strength and increased motor activity in juvenile male rats. Administration of Salifen for 14 days in a dose of 15 mg/kg improved reflex activity and behavior of rats, which indicates the prospect of further study of the therapeutic efficacy of this drug on models of neonatal encephalopathy.

Ectopic neurotransplantation can be used as an in vivo culture method for evaluation of the effect of various environmental factors (neurotransmitters, cytokines, and other bioactive substances) on histogenesis of the developing brain. The study was performed 1 day after allotransplantation of neocortical primordia from embryos of rats receiving intraperitoneal injection of p-chlorophenylalanine on day 11 of pregnancy. Under these experimental conditions the number of degenerating cells increased, while the count of mitotic neuroepithelial cells was 2.5-fold lower compared to neurotransplants of intact embryos at the same stage of development. Incubation of neocortical primordia in serotonin-containing medium before transplantation prevented cell death and promoted division of transplanted cells. Serotonin plays a role in the regulation of neuroepithelial cell proliferation and prevents cell death in the developing neocortex.

Neurons of rat neocortex and spinal cord express NADPH-diaphorase after heterotopic allotransplantation into the sciatic nerve. These peculiarity of diaphorase expression in transplanted cells in comparison with brain cells developing in situ suggest an important role of afferent and efferent relationships in the development of NO mechanisms in neurons.

It was found that intracerebral blood vessels in human embryo telencephalon first appear on the 7th week of prenatal development as capillaries with poorly differentiated walls and signs of functional immaturity. The formation of the basal capillary membrane consisting of laminin and type IV collagen starts immediately after the formation of primary capillary network.

We compared the dynamics of the development of ectopic transplants of embryonic (day 14) primordial neocortex from rats injected with serotonin inhibitor (para-chlorophenylalanine; 400 mg/kg) on day 11 of pregnancy and transplants of similar primordial neocortex incubated before transplantation in a medium with serotonin (3 microg/ml). The study of mitotic activity and differentiation of transplanted cells showed that serotonin promoted survival of the transplanted neuroepithelial cells and their differentiation into nerve cells, and is involved in the regulation of their proliferation. We hypothesized that serotonin accelerated the cell cycle of transplanted cells, thus accelerating the neuron differentiation.

Morphological study of allotransplants of rat embryonic neocortex 14-18 months after transplantation into the neocortex, lateral cerebral ventricle, and sciatic nerve of adult animals revealed death of nerve and glial cells in the delayed postoperation period independently on the site of transplantation. After heterotopic transplantation the count of degenerated neurons was 2 times higher that after homotopic transplantation. In heterotopic transplants a considerable number of grafted neurons underwent reversible and irreversible degenerative changes accompanied by their premature aging. Neuronal death is probably determined by insufficiency of trophic influence from afferent structures and target tissues. We hypothesized that antiapoptotic preparations can be used for prevention of transplanted cell death. It was also found that degeneration of neurons was associated with impaired vascularization of transplants and pronounced immune reaction of the recipient in late posttransplantation period. Transplantation of embryonic brain structures can serve as a model system in studies concerning involutive and pathological processes in the central nervous system and in the search for factors improving survival of neurons.

Neurons of rat neocortex and spinal cord express NADPH-diaphorase after heterotopic allotransplantation into the sciatic nerve. These peculiarity of diaphorase expression in transplanted cells in comparison with brain cells developing in situ suggest an important role of afferent and efferent relationships in the development of NO mechanisms in neurons.