Reaction of the Hippocampal Microglia to Hyperbaric Oxygen.

We studied the reaction of rat hippocampal microgliocytes to hyperbaric oxygen at a pressure of 5 ata (absolute atmosphere). Immunohistochemical analysis with selective macrophage marker CD68 (ED1) and microglial marker Iba-1 allowed separate analysis of these two cell populations. It was shown that macrophages do not significantly contribute to reactive changes in the total pool of Iba-1+ hippocampal cells induced by hyperbaric oxygen.

[ON THE INFLUENCE OF PRENATAL HYPOXIA ON FORMATION OF THE OREXINERGIC SYSTEM AND SLEEP-WAKEFULNESS CYCLE IN EARLY POSTNATAL ONTOGENESIS OF RATS].

The role of orexin in the organization of sleep-wakefulness cycle (SWC) is well known. The aim of this study was to examine the terms of formation of the orexinergic system in the rat postnatal ontogenesis and to assess the role of orexin A in SWC organization under normal conditions and after prenatal hypoxia realized on days 14 and 19 of the embryogenesis. SWC was investigated in 30-day-old rats with elect- rodes implanted into the somatosensory and occipital cortex. Immunoreactivity in the orexinergic structures of the lateral hypothalamus was also studied. It was shown that in the control 14-day-old animals the orexinergic structures were at the formation stage whereas in the 30-day-old ones they were already formed as in adults. In the 14-day-old rats prenatal hypoxia evoked retardation of the orexinergic system for- mation terms. In the 30-day-old rats the orexinergic system activity after hypoxia was increased, with hypoxia on day 19 activating this system stronger than hypoxia on day 14 of gestation. These changes were reflected in the SWC formation in the 30-day-old rats as shortening of the slow-wave phase of sleep, increase in the fitful sleep and in the number of transitions from the slow-wave to the fast-wave phase of sleep. The results obtained are discussed in the light of the adaptation-compensatory role of the orexinergic system in the postnatal ontogenesis after prenatal damage affecting the central neural system.

[Glial fibrillary acidic protein: the component of intermediate filaments in the vertebrate brain astrocytes].

Glial fibrillary acidic protein (GFAP) refers to the type III intermediate filament proteins and is the 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.

[PROSPECTS OF THE NUCLEAR PROTEIN NeuN APPLICATION AS AN INDEX OF FUNCTIONAL STATE OF THE VERTEBRATE NERVE CELLS].

Assessment of safety, viability, and functional state of nerve cells is the major problem in studies of experimental effects on various structures of vertebrate brain and in search for correlation between structural abnormalities and changes in physiological parameters. Such an assessment is possible with applying an immunocytochemical reaction to neuronal nuclear antigen NeuN discovered in 1992. Numerous studies of the protein showed its neural specificity and its amino acid consequence was found to have high interspecies concervatism. This review summarizes and analyzes the available data about the function of the NeuN protein in nerve cells and the results of using this marker for assessment of functional state and viability of CNS neurons in experiments. Particular attention is paid to. the critical analysis of the basic data used for the conclusions on the properties and functions of NeuN. It is stated that there are no satisfactory explanation for lacking the constitutive expression of this marker in some neuronal populations of the mammalian brain and spinal cord. The analysis of our own and literature data presented in the review suggests the future prospects of NeuN labeling for investigation of nerve cell responses to damage including comparative interspecies studies. Key words: brain, neuron, immunocytochemistry, neuronal protein NeuN, vertebrates.

[Subependymal microgliocytes of the third ventricle of the brain].

The goal of the study was to identify the subependymal microglial cells of the III ventricle of the rat brain and to determine their structural characteristics. The sections of the brain of intact Wistar (n = 3) and Sprague-Dawley (n = 3) male rats were studied using the methods of immunocytochemistry and confocal laser microscopy. Subependymal microglia of the III ventricle was found to be a constantly present cell population. Two types of subependymal microgliocytes were identified--spindle-like and basket cells. Their processes penetrate the ependymal layer and reach its surface, thus contacting the cerebrospinal fluid (CSF), which suggests a possible participation of these cells in the structure of CSF-brain barrier.

[Neuroglobin distribution in the human cerebellar cortex (an immunohistochemical study)].

Neuroglobin is a recently discovered heme-containing protein located predominantly in the mammalian brain. This paper for the first time presents the data on neuroglobin distribution in human cerbellum using immunohistochemistry. Neuroglobin immunoreactivity in the cerebellum was found in all the cases studied (n = 7), although its intensity varied. Distinct reaction was found in Purkinje cells and the areas of cerebellar glomeruli.

[Catecholaminergic neurons of mammalian brain and neuromelanin].

Brain catecholaminergic neurons belong to the most extensively studied populations of nerve cells. Presence of a pigment neuromelanin in their cytoplasm is a specific morphological feature of these neurons in many mammalian species. Elucidation of the role of neuromelanin is of importance for comparative neurobiology, as it is absent in neurons of another neurotransmitter systems and, moreover, even in catecholaminergic neurons of some laboratory animals, which limits the possibility of experimental verification of existing hypotheses of its functions under physiological and pathological conditions. For recent years, neuromelanin is an object of particular interest in the scientific community involved in research of neurotoxicity and modeling the Parkinson's disease. The present review summarizes and analyzes new data on the structure and functions of neuromelanin and its probable role in pathogenesis of Parkinson's disease is discussed.

[Comparative aspects of structural organization of astrocytes of the first layer of the human and rat cerebral cortex].

Importance of study of astrocytes for fundamental biology and medicine is due their key role in formation of the brain barrier system. On taking into consideration the controversial data on structure of the mammalian neocortex superficial layers, of great actuality are the comparative studies of the structural and cytochemical organization of astrocytes in human and in the laboratory animals used in the experimental studies connected with modeling of brain diseases and traumas. The goal of the present work was to study structural organization of astrocytes in the human and rat neocortical layer I. The work was on the autopsy and experimental material from Wistar rats. Astrocytes were revealed immunocytochemically by using antibodies to GFAP, vimentin and nestin. The preparations were examined with aid of light and confocal laser microscopy. No significant difference in the sizes of perinuclear areas were established between the rat and human astrocytes. In the majority of cortex regions, the specter of proteins forming intermediate filaments in these cells was identical. However, there were essential differences revealed in organization of the superficial glial bordering lamina (SGBL). The human SGBL is formed by interlacing of thin processes in the layer I processes, whereas the rat SGBL is represented by specialized astrocytes spread along the cortical surface and connected with the wide-blade processes. The human layer I astrocytes have translaminar processes passing via several cortical layers, whereas in rats such processes are located within the limits of one layer. The revealed differences in the astrocyte structural organization should be taken into account when interpreting results of experimental studies carried out on rats and extrapolating these results to human.

Prenatal Hypoxia Impairs Olfactory Function in Postnatal Ontogeny in Rats.

Analysis of the age-related dynamics of olfactory behavior in the odor preference and food search testsshowed that all male Wistar rats, regardless of age, preferred valerian essential oil, whose components have the properties of pheromones in rodents, when given a selection of eight essential oils; young rats displayed better food-seeking results than adult and old animals. Acute prenatal hypoxia (PH) on E14 (7% O2 for 3 h) led to impairment of the valerian odor preference at all ages studied and to decreased productivity of food searches. Neurodegenerative processes were seen in the piriform cortex after PH, with reductions in the number of neurons and increases in glial elements. We have previously observed these changes in the entorhinal cortex and hippocampus, but not in the olfactory bulbs. This suggests that PH-induced decreases in olfactory function in rats may result from impairments to the formation of the central elements of the analyzer during the first months of postnatal ontogeny.

[Neural stem cell marker MSI-1 expression in rat telencephalon].

The aim of the study was to examine the distribution of cells expressing Msi-1 (Musashi-1) protein which is believed to be a marker of neural stem cells, in rat telencephalon. These cells were found to be concentrated in the subventricular proliferative zone and diffusely scattered in striatum and hippocampus. Moreover, neurons with extensive Msi-1 reaction were found in habenular nuclei. The data obtained are not in full agreement with current views on the localization of neural stem cells in the brain.

[Astrocytes of the subventricular zone of the telencephalon].

Subventricular proliferative zone is the brain area most intriguing and least understood in terms of cellular and spatial organization. The objective of this study was to focus on the structural and cytochemical organization of astrocytes of the subventricular zone of the rat brain. Astrocytes were detected immunocytochemically. The preparations were analyzed using conventional light microscopy and confocal laser microscopy. The study performed showed that the major cellular population of the subventricular zone was represented by a special kind of atypical fibrous astrocytes with the intermediate filaments containing only glial fibrillary acidic protein (GFAP). The processes of these cells formed a complex double-layer network beneath the ependyma. The described structural pattern of the glial skeleton of the subventricular zone seems to be determined by specific functions of the area and its location in the zone of CSF-brain barrier.

[Structural organization of superficial glial limiting membrane and layer I astrocytes in rat brain cortex].

A study of structural and functional organization of the boundaries separating CNS compartments is a fundamental task of neurobiology. Taking into account the contradictory data on the structure of superficial layers of mammalian neocortex, it is pertinent to study structural and cytochemical organization of astrocytes--the main components of the brain barrier system in animals that are often used for experimental modeling of brain diseases and injuries. The aim of the present work was to study the structural organization of layer I astrocytes of rat neocortex. Astrocytes were demonstrated immunocytochemically using anti-GFAP, anti-vimentin and anti-nestin antibodies using light and confocal laser microscopy. The results of the study demonstrated that the superficial glial limiting membrane had significant structural differences in different cortical regions. Astrocytes in layer I of rat neocortex were different from typical protoplasmic astrocytes, common to gray matter The regional peculiar features of superficial glial limiting membrane organization that were found in this study, are probably determined by the differences in functional characteristics of CSF-encephalic barrier in the specific regions of the brain.

[Preadaption to nitrogen anesthesia and impairment of brain cortex structure in rats 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 manifestations of the anesthesia by 60-67%. The immunocytochemical light optical microscopy showed that in the brain cortex after the 8th séance 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 séances the number of cells with no reaction for the nuclear protein NeuN increased, while after its 8th séance the areas of the absence 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 séances 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 at use of the hypoxic action, it is better to use as a preadaptogen the more moderate or not too frequent hypoxia.

[Fatty acids of phospholipids of brain cell nuclei in rat ontogenesis].

Experiments were carried out on the 19-day old rat embryos, the 5- and 45-day old rat pups, and the 1.4-1.5-year old rats. Phospholipids and their fatty acid composition in brain cell nuclei were studied using methods of extraction, two-dimensional thin-layer chromatography, and spectrofluorimetry. In the course of ontogenesis, the percentage of different classes of nuclear phospholipids was changed; at the postembryonic period, the unsaturation index of lipids (phosphatidylcholine and phosphatidylethanolamine) and the content of unsaturated (especially polyenic) fatty acids decreased. Microviscosity of nuclear membranes increased; this changes were also shown earlier in phylogenesis of vertebrates. Thus, the facts revealed in the present work correspond to the recapitulation law. It is suggested that such change of lipid ratio and of composition of their fatty acids as well as of the membrane microviscosity serve for regulation of functions of membrane proteins and have adaptive character.

[Effect of nitric oxide/endothelin interaction on hyperoxic vasoconstruction].

The data obtained demonstrated that NO restrains ET-1 production and blunts ET-1-mediated basal cerebrovascular tone. Local hyperoxygenation of the brain tissue decreases NO availability, supeoxide production, suppresses NO-mediated vascular tone and facilitates ET-1-mediated vasoconstriction.