Flavonoid quercetin reduces gliosis after repetitive mild traumatic brain injury in mice.

The effect of water-soluble form of quercetin on the structural changes of glial cells in hippocampus was investigated in mice after repetitive mild traumatic brain injury. Reactive astro- and microgliosis in hippocampus were observed after brain injury. Iba 1 and GFAP immunohistochemistry was used to visualize astrocytes and microglia cells. Immunopositive cells were counted in hippocampal CA 1-area at 5th, 10th and 30th days since thefirst injury and at 5th, 10th and 30th days since thefirst quercetin injection. Administration of quercetin leaded to the decrease in number of activated glial cells. Thus, our study demonstrates thefollowing: repetitive mild traumatic brain injury in mice is associated with reactive gliosis; quercetin showed neuroprotective effects by reducing this gliosis. In view of the described, use of quercetin is appropriate for pharmacological correction of cerebrovascular disorders after traumatic brain injury.

[Role of neural stem cells in regeneration of the central nervous system].

Central nervous system (CNS) of adult mammalian and, in particular of people, is a typical example of organs that are not restored. However, the growing interest in the development of innovative treatments that are aimed at the regeneration damaged tissue CNS is based on the latest research in the field of stem cells and neurology. The recapitulation of normal neural development has become a vital strategy for CNS regeneration. Normal CNS development is initiated by the induction of stem cells in the CNS, i.e., neural stem cells (NSCs). Thus, the introduction or mobilization of NSCs could be expected to lead to CNS regeneration by recapitulating normal CNS development, in terms of the activation of the endogenous regenerative capacity and cell transplantation therapy. In this review we summarized the recent progress in study of basic stem cell biology, on the prospective identification of NSCs, the elucidation of the mechanisms of ontogenic changes, potential differentiation, and their therapeutic applications.

[Migration and differentiation of transplanted fetal neurogenic cells in animals with brain ischemia].

The migration, integration and differentiation of fetal neural progenitor cells (NPCs) in the ischemic brain have been studied. In our study the ischemic insult in FVB line mice was produced by occlusion of both carotid arteries during 20 min. A day after occlusion NPCs from GFP-transgenic 12.5 dpc embryos were suboccipitally transplanted to the ischemic brain. The migration and differentiation of GFP-positive NPCs in the recipient tissue were observed in different time points after their transplantation by immunohistochemical approaches using confocal scanning microscopy. It has been shown that GFP-positive NPCs survived, migrated and differentiated to the mature neurons and glial cells in CA1 area of hippocampus of ischemic animals.

Microglia in normal condition and pathology.

Microglia, one of three types of glial cells in the central nervous system (CNS), plays an important role as resident immunocompetent and phagocytic cells in CNS in the event of injury and disease. It was del Rio Hortego who in 1927 determined that microglia belong a distinct glial cell type apart from astrocytes and oligodendrocytes. Since 1970s there has been wide recognition that microglial cells are immune effectors in the CNS that respond to pathological conditions and participate in initiation and progression of neurological disorders including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and acquired immune deficiency syndrome dementia complex by releasing potentially cytotoxic molecules such as proinflammatory cytokine, reactive oxygen intermediates, proteinases and complement proteins. There is also evidence to suggest that microglia is capable of secreting neurotrophic or neuron survival factors upon activation during inflammation or injury. It is thus timely to review the current status of knowledge on origin, morphology and functional features of microglial cells.

Remodeling of ammon's horn during the first two weeks of experimental diabetes development.

It is known that long-term diabetes mellitus causes hippocampal dysfunction, however, early events leading to diabetes-related impairments of hippocampal tissue remain obscure. The present study was performed to examine temporal and spatial patterns of neuronal damage and astrogliosis in hippocampal CA1-C3 areas during the early stage of streptozotocin-induced diabetes in rats. NeuN and GFAP immunohistochemistry was used to visualize neurons and glial cells. Immunopositive cells were counted in hippocampal CA1-CA3 areas at days 3, 7 and 14 of diabetes development using confocal Olympus FV1000 microscope. Significant decrease in the number of neurons in CA2 area was observed in diabetic rats at day 3. In contrast, in CA1 and CA3 areas NeuN-positive cell count started to decrease later being at day 7, correspondingly, by 7 and 9 % lower than that in the control. This trend developed further till day 14, when the number of neurons in CA1 and CA3 areas was, respectively, 20.3 and 18.1% smaller as compared with the control. These changes were accompanied by astrogliosis: the number of astrocytes in pyramidal cell layer was increased significantly in all examined time-points. Thus, our study demonstrates that streptozotocin-induced diabetes is associated with early neurodegeneration in Ammon's horn. It suggests that clinically relevant cognitive deficits development in diabetic patients starting from the early stage of the disease.

[Neuroprotective effect of quercetin during experimental brain ischemia].

The neuroprotective action by water-soluble form of quercetin was examined in gerbils after transient forebrain ischemia. The animals were exposed to 7 min of bilateral common carotid artery occlusion. Hippocampal CA 1 area was examined 7 days after ischemia-reperfusion. The average density of CA1 pyramidal neurons and GFAP-positive glial cells were counted in sham operated group, in ischemic group and in the groups treated with water-soluble form of quercetin. It was shown that quercetin revealed protective effect by decreasing of delayed neuronal death and reducing reactive astrogliosis after ischemia-reperfusion.

Estimating transmitter release rates and quantal amplitudes in central synapses from postsynaptic current fluctuations.

Several approaches recently introduced to analyze release rates in central synapses advanced our understanding of synaptic neurotransmission, however, leaving many questions still unresolved. In this work we present evidence that a new method recently developed by Sakaba and Neher to study neurotransmission in calyx of Held, a giant glutamatergic synapse, could be also applied for estimating release rate functions and averaged quantal sizes in small central synapses. By means of different simulation approaches applied to reproduce GABAergic neurotransmission in the hippocampus we have shown that possible problems with a spatial voltage clamp which can occur in synaptic connections distributed over a large area of dendritic tree are not crucial for applicability of the method when synapses are compactly distributed or located proximally and when release rates are below 1 ms(-1). In another set of simulations we have also shown that at above mentioned release rates desensitization and/or saturation of postsynaptic GABAA receptors does not prevent accurate estimates of release rate and averaged quantal size. Thus, we conclude that the new approach based on analysis of fluctuations of postsynaptic currents under conditions of stationary release or moderately nonstationary conditions might be applicable to studies of small central synapses.

Myelination and demyelination processes in the rat cerebellum cell culture: an electron microscopic study.

We observed manifestations of the myelination process in dissociated culture of the cerebellar tissue of newborn rats and modifications of the structure of myelin sheaths after treating the culture with a demyelinating factor, blood serum of patients suffering from multiple sclerosis (MS). On day in vitro (DIV) 26, in the control myelin sheaths of the axons demonstrated the closest resemblance to those observed in vivo, and we selected this term for inducing demyelination. Addition of the serum of MS patients to the culturing medium evoked rapid (in 3-6 hours) dramatic changes in the ultrastructure of myelin sheaths; these were a decrease in the number of the lamellae, their splitting and invagination, formation of vesicles, etc. The serum of MS patients in an acute stage of the disease exerted more intensive demyelination effects than that of patients in a remission stage.

GFAP promoter-controlled EGFP-expressing transgenic mice: a tool to visualize astrocytes and astrogliosis in living brain tissue.

We have generated transgenic mice in which astrocytes are labeled by the enhanced green fluorescent protein (EGFP) under the control of the human glial fibrillary acidic protein (GFAP) promoter. In all regions of the CNS, such as cortex, cerebellum, striatum, corpus callosum, hippocampus, retina, and spinal cord, EGFP-positive cells with morphological properties of astrocytes could be readily visualized by direct fluorescence microscopy in living brain slices or whole mounts. Also in the PNS, nonmyelinating Schwann cells from the sciatic nerve could be identified by their bright green fluorescence. Highest EGFP expression was found in the cerebellum. Already in acutely prepared whole brain, the cerebellum appeared green-yellowish under normal daylight. Colabeling with GFAP antibodies revealed an overlap with EGFP in the majority of cells. Some brain areas, however, such as retina or hypothalamus, showed only low levels of EGFP expression, although the astrocytes were rich in GFAP. In contrast, some areas that were poor in immunoreactive GFAP were conspicuous for their EGFP expression. Applying the patch clamp technique in brain slices, EGFP-positive cells exhibited two types of membrane properties, a passive membrane conductance as described for astrocytes and voltage-gated channels as described for glial precursor cells. Electron microscopical investigation of ultrastructural properties revealed EGFP-positive cells enwrapping synapses by their fine membrane processes. EGFP-positive cells were negative for oligodendrocyte (MAG) and neuronal markers (NeuN). As response to injury, i.e., by cortical stab wounds, enhanced levels of EGFP expression delineated the lesion site and could thus be used as a live marker for pathology.

[Physiologic energy requirements of miners working in deep coal mines]. / Fiziologicheskaia potrebnost' v énergii gornorabochikh glubokikh ugol'nykh shakht.

A time course study of energy balance was conducted in miners working in deep coal mines under a strict control of their nutrition using the method of estimating the energy value of food received and body mass. It has been established that mean daily energy requirement of a "standard" miner (body mass--70 kg, age--25-35 years) comprises 16529.7 kJ (3950.7 kcal) under conditions of fulfillment of the standard output, 6-hour working day, 2 days off.

[ATP level in synaptosomes--a determining factor of the functional activity of ion channels induced by alpha-latrotoxin]. / Uroven' ATP v sinaptosomakh--opredeliaiushchii faktor funktsional'noi aktivnosti ionnykh kanalov, indutsiruemykh alpha-latrotoksinom.

The paper deals with characteristics of relationship between synaptosomal calcium permeability induced by alpha-latrotoxin and cytosolic concentration of ATP. It is shown that reagents decreasing the ATP level in the synaptosomes (monoiodoacetate, papaverine) inactivate the toxin-induced ionic fluxes and, on the contrary, reagents increasing the ATP level in synaptosomes enhance the toxin-induced calcium influx. The treatment of synaptosomes with inhibitors of phosphodiesterase of cAMP and cAMP-dependent protein kinase has no effect on the alpha-latrotoxin-induced calcium influx.

[Interaction of alpha-latrotoxin with synaptosomes; metabolic control of the induction of calcium channels]. / Vzaimodeistvie alpha-latrotoksina s sinaptosomami; metabolicheskii kontrol' induktsii kal'tsievykh potokov.

The aim of the present study is to elucidate the possible significance of metabolic control of the calcium permeability of synaptosomes induced by alpha-latrotoxin. The alpha-latrotoxin influence of processes of GABA release and reuptake is shown to depend on synaptosomal metabolism. It has been found that incubation by the synaptosomes during one hour at 37 degrees C or their treatment by 10(-3) M monoiodacetate during 10 min at 10 degrees C or at room temperature completely abolished or at least strongly decreased the ability of alpha-latrotoxin to induce the calcium influx. Under the same conditions the ability of alpha-latrotoxin to activate the GABA release and inhibit the GABA reuptake do not change. It is concluded that only formation of calcium channels by alpha-latrotoxin is strictly controlled by the level of synaptosomal metabolism.

[Calcium permeability of synaptosomes induced by alpha-latrotoxin]. / O kal'tsievoi pronitsaemosti sinaptosom, indutsirovannoi alpha-latrotoksinom.

The paper deals with characteristics of ionic alpha-latrotoxin-induced permeability of rat brain synaptosomes. It has been shown that the addition of alpha-latrotoxin to synaptosomes in the Ca2+-containing media resulted in an extensive and rapid uptake of 45Ca2+ in synaptosomes. alpha -Latrotoxin was not able to enhance the 22Na+ and 86Rb+ uptake or efflux in the Ca2+-containing and Ca2+- and Mg2+-free media. The dye di-O-C3 was used to monitor the membrane potential changes as a consequence of alpha-latrotoxin treatment of synaptosomes. It has been found that alpha-latrotoxin increased synaptosomal fluorescence in the Ca2+-containing media, but failed to induce any increase of fluorescence in Ca2+- and Mg2+-free media. It has been also shown that the calcium uptake induced by alpha-latrotoxin depends on free calcium concentration in synaptosomes. Toxin-induced calcium flows are shown to be of the vector character.