O. S. Alekseeva

Distribution of Neuroglobin in the Human Cerebellar Cortex (an immunohistochemical study)

Neuroglobin is a recently discovered heme-containing protein located mainly in the brain in mammals. We report here the first data on the distribution of neuroglobin in the human cerebellum, obtained from immunohistochemical studies. Reactions for neuroglobin were seen in all the cases studied (n = 7), though its intensity varied. Clear reactions were seen in Purkinje cells and in the cerebellar glomeruli.

Glial fibrillary acidic protein: The component of iintermediate filaments in the vertebrate brain astrocytes

Glial fibrillary acidic protein (GFAP) refers to the type III intermediate filament proteins and is an essential component of the cytoskeleton in astrocytes of all vertebrates. This review presents current data on the molecular organization of GFAP in a comparative aspect. The results of most relevant studies using immunocytochemical labeling of the protein are summarized. The data on the changes in expression of GFAP in Alexander disease caused by the primary pathology of astrocytes are presented.

Catecholaminergic Neurons of Mammalian Brain and Neuromelanin

The brain neurons synthesizing catecholamines are ones of the most studied populations of nerve cells. The most essential morphological difference of these cells in many mammalian species—the presence of pigment neuromelanin in their cytoplasm. The issue of role of neuromelanin in cell seems important for comparative neurobiology, as it not only is absent in neurons of different transmitter nature, but even in catecholaminergic neurons in some species of laboratory animals, which restricts possibilities of experimental testing of available hypotheses about its functions in norm and in pathology. For the last few years neuromelanin attracts particular interest in the researchers studying neurotoxicity and modulation of Parkinson’s disease. In the presented review there are generalized and analyzed novel data about structure and functions of neuromelanin, as well as discussed is its possible role in pathogenesis of Parkinson’s disease.

Prospects for the application of neun nuclear protein as a marker of the functional state of nerve cells in vertebrates

Assessment of the integrity, viability and functional state of nerve cells is a major problem in studying the effect of experimental exposures on different brain structures in vertebrates and correlating structural abnormalities with changes in physiological parameters. Such an assessment is possible due to the use of the immunocytochemical reaction for NeuN, a neuronal nuclear protein discovered in 1992. Numerous studies have demonstrated that this protein is neuron-specific, while its amino acid sequence shows a high degree of interspecies conservatism. In the present review, the available information about the functions of NeuN in nerve cells and results of its application for the assessment of the functional state and viability of CNS neurons during experiments are generalized and analyzed. A special focus is on the critical analysis of the data that allowed the properties and functions of NeuN to be deduced from. The still poorly explained facts of the constitutionally lacking expression of this biomarker in some neuronal populations of the mammalian brain and spinal cord are also discussed. The analysis of our own and literature data reveals a great potential of the NeuN labeling in studying the responses of nerve cells to damage, including comparative interspecies studies.

Intranuclear localization of iron in neurons of mammalian brain

Using Perls’ histochemical method, iron was revealed in the brain structures of human and rat. Iron accumulation was observed in perivascular areas and neuropil of substantia nigra as well as in white matter of cerebellum. After diaminobenzidine enhancement of histochemical reaction, the iron was revealed in nucleoli of many neurons, which is described for the first time in animal cells.

On the influence of prenatal hypoxia on formation of the orexinergic system and sleep–wake cycle in early ontogenesis of rats

The role of orexin in the organization of the sleep–wake cycle (SWC) is well known. The aim of this study was to examine the timing of the orexinergic system formation in rat postnatal ontogenesis and to assess the role of orexin A in the SWC organization under normal conditions and after prenatal hypoxia undergone on days 14 and 19 of embryogenesis. The SWC was investigated in 30-day-old rats with electrodes implanted into the somatosensory and occipital cortex. Immunoreactivity within the orexigenic structures of the lateral hypothalamus was analyzed. It was shown that in control 14-day-old animals the orexinergic structures were in their formative stage, whereas in 30-day-old rats they were already as formed as in adults. In 14-day-old rats, prenatal hypoxia evoked retarded formation of the orexinergic system. In 30-day-old animals, hypoxia undergone in the prenatal period increased the activity of the orexinergic system, which was higher in animals exposed to hypoxia on day 19 than on day 14 of gestation. In 30-day-old rats, these changes were reflected in the SWC formation in the form of shorter slow-wave sleep, more fitful sleep and increased number of transitions from slow- to fast-wave sleep. The results obtained are discussed in the light of the adaptive-compensatory role of the orexigenic system in postnatal ontogenesis after prenatal damage to the central nervous system.

Intermediate filament proteins in tanycytes of the third cerebral ventricle in rats during postnatal ontogenesis

Cytoskeletal intermediate filaments (IF) are composed of proteins able to form homo- and heterodimers, while their repertoire can change during cell differentiation. Data on the IF protein composition in tanycytes lining the mammalian third cerebral ventricle are still discrepant. The aim of this study was to investigate age-related changes in the IF protein composition in tanycytes of the third cerebral ventricle in Wistar rats at different ages (7-, 14-, and 30-day-old pups and 4–5-month-old adults; n = 26), using immunocytochemistry and confocal laser microscopy. In adult animals, tanycytes were shown to express IF proteins vimentin, GFAP, and nestin. In different types of tanycytes GFAP and nestin begin to be synthesized at different postnatal ages. For example, in α1 tanycytes GFAP is already present in 7-day-old animals, while in β1 tanycytes it appears only by day 30 of postnatal development. Meanwhile, vimentin is an essential IF component at all ages studied. A comparison of our data with the results obtained on other animal models suggests the existence of species-specific differences in the IF protein repertoire in tanycytes.

Effects of hyperbaric oxygenation on subependymal microglia of the rat brain

not yet well understood. We only know that HBO enhances production of reactive oxygen species (ROS) that oxidize cell structures and produce neurochemical changes that lead to neurotoxicity [2]. Microglia is one of the most important effector cells of the nervous tissue, mediating the damaging effects of various environmental factors. For example, low lead concentrations resulted in a decrease of the number of microglial cells [3], while during ischemia the proliferation and migration of these cells is observed [4]. This fact may indicate the oxygen sensitivity of the microglial cells. However , there are no data concerning the reaction of microglia to the impact of HBO. The goal of this work was to study effect of HBO on the state of subependymal microglia—an essential element of the cerebrospinal fluid–brain barrier. The study was performed on male Wistar rats weighing 200–250 g (n = 12). The HBO séance for 6 animals was carried out in a hyperbaric chamber of 107-l-volume at an oxygen pressure of 0.3 MPa for 4 h. During this time period the chro-noconcentration effect of oxygen did not lead Hyperbaric oxygenation (HBO) is a method of oxygen saturation of an organism under high pressure , which is used in medical and diving practice in preventive and curative purposes [1]. Application of HBO is accompanied by positive effects that are related to a possibility of compensating the oxygen debt of the organism in insufficient external respiration or oxygen-binding function of blood, deficiency of regional and general supply , etc. HBO promotes deceleration and deeper breathing, a slowing of the heart rate, decreases the cardiac output and volume of the organ blood flow, increases the peripheral vascular resistance, improves myocardial contractility, and increases its functional reserve. Also, HBO increases essentially the level of regenerative processes. However, if the concentration of hyperbaric oxygen exceeds the therapeutic level, a neurotoxic effect is evident , which is manifested in development of oxygen convulsions. The HBO-induced physiological and pathological reactions of the central nervous system have long been known phenomenologi-cally, but the molecular mechanisms of oxygen toxicity and the occurring cellular responses are

Preadaptation to nitrogen anesthesia and impairment of rats brain cortex structure during hypoxia

The attenuating effect of various variants of hypoxia on hyperbaric anesthesia in rats was studied. The most efficient turned out to be the daily 8-fold one-hour interval 6% hypoxia that decreased manifestation of the anesthesia by 60–67%. The immunocytochemical light optical microscopy showed that in the brain cortex after the 8th seance of such hypoxia the number of neurons with the strong and moderate reaction to heat shock proteins (HSP-70) increased essentially, whereas the number of neurons with the weak reaction to these proteins decreased significantly. After the first hypoxia seances the number of cells with no reaction for the nuclear protein NeuN increased, while after its 8th seance the areas of deletion of neurons appeared. It is believed that one of the main causes of an increase of resistance of the rat organism to nitrogen anesthesia after seances of the many-day interval 6% hypoxia is accumulation of HSP-70 in brain motor cortex cells. At the same time, taking into account a possible cell death and areas of deletion of neurons in cortex during the hypoxic action, it is better to use as a preadaptogen the more moderate or not too frequent hypoxia.

Neuroglobin, an oxygen-binding protein in the mammalian nervous system (localization and putative functions)

The review summarizes current data on neuroglobin, the heme-containing protein discovered in mammalian nerve cells in 2000. It presents general characteristics of neuroglobin as well as data on its evolutionary changes and expression across different taxa. Neuroglobin distribution in specific brain structures and outside the brain is described. The issue of the occurrence of neuroglobin not only in neurons but also in astroglial cells is discussed. Subcellular localization of neuroglobin is characterized with a special focus on its detection in the nucleus of nerve cells, suggesting its involvement in nuclear functions. Current ideas on the probable functional significance of neuroglobin are reported. Neuroglobin is presumed to be involved in metabolism of reactive nitrogen and oxygen species as well as in intracellular signaling pathways. Besides, neuroglobin has neuroprotective and antiapoptotic functions. Since its expression changes during ontogenesis, its neuroprotective role in ageing is specifically highlighted. Changes in expression and localization of neuroglobin are suggested to influence the adaptive potential of an organism.