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Journal Cover Neurophysiology
   [3 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1573-9007 - ISSN (Online) 0090-2977
     Published by Springer-Verlag Homepage  [2210 journals]   [SJR: 0.136]   [H-I: 7]
  • Activity of Different Populations of Neurons of the Bulbar Respiratory
           Center of Rats in the Dynamics of Hypobaric Hypoxia
    • Abstract: We examined the involvement of different groups of inspiratory and expiratory neurons, INs and ENs, respectively, of the bulbar respiratory center, RC, in the control of respiration under conditions of hypobaric hypoxia. Such conditions were created in a laboratory altitude chamber and corresponded to a “lift” up to 8000 m altitude. At the beginning of such a “lift,” at a pressure corresponding to an altitude of 4000–5000 m, a decrease in the pO2 in the inspired air to 98–85 mm Hg induced increases in the frequency of spiking of the examined neurons. Within a phase of extreme hypoxia, at an “altitude” of 7500 to 8000 m (pO2= 64–58 mm Hg), we observed considerable suppression of the activity of bulbar respiratory neurons. Impulse activity of INs and ENs within different stages of hypoxia demonstrated considerable specificity; INs were characterized by relatively higher resistivity with respect to the action of this factor. Among subgroups of these units, “early” and “full” INs were found to be more resistive with respect to the oxygen insufficiency. After “descent” of the animals and recovery of the normal atmospheric pressure, characteristics of spiking of most bulbar respiratory neurons gradually returned to the initial values.
      PubDate: 2014-12-09
       
  • Short-Term Plasticity of Glutamatergic and GABA-Ergic Synaptic
           Transmission between Co-Cultured Retinal Ganglion Cells and Superior
           Colliculus Neurons
    • Abstract: We studied changes in the efficacy of synaptic transmission via glutamatergic and GABA-ergic synaptic connections between co-cultured retinal ganglion cells (RGCs) and neurons of the superior colliculus (SC) at paired stimulation of RGCs (as a form of short-term synaptic plasticity). In a parallel manner, we recorded transmembrane currents and potentials in synaptically connected pairs of RGCs and SC neurons using the paired whole-cell patch-clamp technique. When glutamatergic synaptic action was mediated by activation of exclusively NMDA or non-NMDA receptor channel complexes on the postsynaptic membrane of SC neurons, depression of synaptic transmission after the second AP was observed. In the case of GABA-ergic transmission mediated by activation of GABAА receptor-channel complexes, analogous paired stimulation resulted in facilitation of synaptic action on an SC neuron after the second AP generated by an RGC. The use of basic and complete quantal analyses allowed us to find a significant decrease (Р < 0.05) in the binomial parameter n in the case of depression of NMDA-mediated evoked postsynaptic currents (ePSCs) and a significant drop in both quantal parameter q and binomial parameters n and p at depression of non-NMDA-mediated ePSCs. In the former case the estimate was indicative of possible presynaptic localization of the mechanisms of depression resulting from a decrease in the number of released synaptic vesicles containing the transmitter, while in the latter case not only pre- but also post-synaptic mechanisms (decrease in the number of released synaptic vesicles and desensitization of postsynaptic receptors) are probably involved. Estimation of normalized alterations of the quantal and binomial parameters at facilitation of GABAА-mediated ePSCs demonstrated a significant increase (Р < 0.05) in the presynaptic factors n and p and, correspondingly, in the quantal content m. Therefore, the effect of facilitation can be due to the processes realized in a presynaptic terminal (enhancement of the number of synaptic vesicles).
      PubDate: 2014-12-09
       
  • Do Results of the Open Field Test Depend on the Arena Shape'
    • Abstract: The open field test (OFT) is one of the main methods used for the estimation of behavioral indices and emotionality levels in animals. This test is widely used in toxicological and pharmacological studies. The question of whether the arena shape influences the results of testing remained open. This is why we compared the results of the mentioned test using one and the same species of laboratory animals (rats), identical conditions of testing, and arenas of nearly the same area but of a round or square shape. Significant differences were found in only two examined parameters, frequency of realization of the burrow reflex and intensity of “internal” horizontal motor activity; other indices showed nearly no considerable differences. Thus, it can be concluded that the results of behavioral studies carried out under the above two conditions are rather similar to each other in their adequacy.
      PubDate: 2014-12-09
       
  • Peculiarities of Microhemocirculation in the Rat Brain after Different
           Modes of Cold Acclimation
    • Abstract: Different regimes of cold acclimation (continuous and rhythmic) led to specific changes in the microcirculatory bed of the pia of the rat brain. In the course of long-term (1 month) continuous stay of rats at a low temperature, alterations of microcirculation were similar to those observed after acute short-term cold action, while repetitive short-term episodes of cold action during the same time interval (1 month) induced no vasoconstriction in the arterial link and no venous congestion resulting in ischemization of the brain. Synergistic or antagonistic actions on the vascular tone of local (nitric oxide) and central neural and humoral (catecholamines) factors can underlie the specificities of these phenomena.
      PubDate: 2014-12-09
       
  • Effects of Electrical Stimulation of the Cerebellum and Injections of
           Levetiracetam on Aggressive Behavior of Kindling Rats
    • Abstract: In rats with the corazole-induced kindling syndrome, we estimated the conditions for the appearance of battles on an electrified floor; the threshold for initiation of aggressive reactions in kindling animals was lower, on average, by 41.5%, as compared with the corresponding index in intact animals. Combination of electrical stimulation (ES) of the paleocerebellar cortex (lobules V-VII; 100 sec–1; altogether 10 sessions of ES) and injection of levetiracetam (40.0 mg/kg, i.p.), which per se did not influence significantly aggressive behavior of kindling rats, led to an increase in the threshold for the appearance of battles, on average, by 28.8% (P < 0.05), compared with the initial value in the tested animals, i.e., to a drop in the level of aggressiveness.
      PubDate: 2014-12-09
       
  • Effects of Transduction of the bcl-2 Gene and of Nerve Growth Factor on
           Apoptosis of Cultured PC12 Cells
    • Abstract: We examined what effects are exerted by expression of the bcl-2 gene and by treatment with nerve growth factor (NGF) on the intensity of apoptosis in cultured pheochromocytoma cells (PC12 cells). Half of these cells were transduced with the bcl-2 gene using lentiviral plasmids, and the respective two groups were denoted as bcl-2-PC12 and control (c) PC12. Then the cells were incubated in a serum-free medium in six different modes. One group of c-PC12 cells was incubated in this medium with no additional agents added, another group was incubated with 1.0 mM H2O2, and the third group was incubated with both 1 mM H2O2 and 20 ng/ml NGF (groups 1-3). Cells of another triad were incubated under the same conditions, respectively, but these were bcl-2-PC12 cells (groups 4-6). The apoptosis rate in each group after 1-h-long incubation was measured using a flow cytometry method. A bicinchoninic acid (BCA) technique was used for estimation of expression of Bcl-2 protein in the cultures. As was observed, the action of H2O2 significantly increased the apoptosis rate in both c-PC12 and bcl-2-PC12 samplings, while the simultaneous action of NGF considerably attenuated such increases. At the same time, values of the apoptosis rate for bcl-2-PC12 cells were much smaller than the respective values for c-PC12 cells under all the three modes of incubation. In H2O2-treated cultures, the amount of Bcl-2 protein dropped, while treatment with NGF counteracted such shifts. The content of this protein in the bcl-2-PC12 groups was much higher than in the c-PC12 groups. Thus, transduction with the bcl-2 gene significantly inhibits apoptosis in cultured PC12 cells, and the combined influence of expression of this gene and treatment with NGF produces a synergistic effect.
      PubDate: 2014-12-09
       
  • Effects of Acute Intracerebroventricular Microinfusions of Bupropion on
           Background Spike Activity of Locus Coeruleus Neurons in Rats
    • Abstract: Considering that noradrenergic (NAE) neurons of the locus coeruleus (LC) play significant roles in the formation of biological rhythms, pain, addictions, and mood disorders, we tested the effects of acute intracerebroventricular microinfusions of bupropion, an inhibitor of NA reuptake used in clinics as an antidepressant, on background spike activity on LC neurons in chloral hydrate anesthetized rats. Ten microliters of the solutions containing 0.001, 0.01, 0.1, 1.0, or 10.0 μmol bupropion were infused during 3 min; spike activity of single LC neurons identified according to the known characteristics was recorded extracellularly by glass microelectrodes. Microinfusions of 0.01 to 10.0 μmol bupropion suppressed background spiking of the above neurons in a dose-dependent manner. The normalized mean intensities and durations of inhibition were 17.3, 19.4, 26.3, and 41.1% and 1.4, 7.1, 12.4, and 18.3 min, respectively. The smallest dose (0.001 μmol) was ineffective. It is assumed that bupropion increases the NA level in proximity to NAE LC neurons. The actions of bupropion on other cerebral neuromodulatory systems need further examination. Inhibition of LC neuronal activity by bupropion can help to explain some acute, chronic, and side effects of this agent used in clinics for correction of mood disorders.
      PubDate: 2014-12-09
       
  • Spike Timing-Dependent Plasticity in CA1 Pyramidal Neuron-Controlling
           Hippocampal Circuits: a Model Study
    • Abstract: Spike timing-dependent plasticity (STDP) plays an important role in sculpting neural circuits to store information in the hippocampus, since motor learning and memory are thought to be closely linked with this type of synaptic plasticity. We built a computational model to study the potential learning rule by linearly changing the synaptic weight and number of the synapses involved. The main findings are the following: (i) changes in the synaptic weight and number of synapses can lead to different long-term changes in the synaptic efficacy; (ii) the first spike pair of two neurons exerts a great influence on the subsequent spike pair; a pre-post spiking pair reinforces the subsequent paired spiking, while a post-pre spiking pair depresses this paired spiking; (iii) when the synaptic weight and synaptic number change, the interval in the first spiking pair is reduced, which directly influences the first spiking pair, and (iv) when a stellate neuron is stimulated weakly or the capacitance of a CA1 pyramidal neuron is decreased, LTP is produced more easily than LTD; in the opposite case, LTD is produced more readily; an increase of the synaptic number can promote activation of CA1 pyramidal neurons.
      PubDate: 2014-12-09
       
  • Neurotropic Properties of Novel Alkyl Derivatives of
           1,3,4-Benzotriazepines
    • Abstract: We studied the neurotropic properties of four novel derivatives of 1,3,4-benzotriazepines. The tested compounds were i.p. injected in doses of 1.0 or 10 mg/kg. We estimated motor and research activity of these compounds in the open-field test, their anticonvulsive effects under conditions of acute corazoleinduced seizures, anorixogenic and antidepressive effects, and also the acute and chronic toxicity of these agents. The latter properties of all studied compounds were found to be relatively low. In doses of 10 mg/kg, the tested agents decreased general motor activity, influenced the appetite of animals, and did not exert depressive effects. Therefore, the obtained data are indicative of the expedience of further search for alkylthio derivatives of 1,3,4-benzotriazepine with different functional groups connected to the heterocycle because such agents possess clearly pronounced sedative, anorexigenic, or orexigenic properties.
      PubDate: 2014-12-09
       
  • Correlations between the Amount of Oxidatively Modified Proteins and
           Proteolytic Activity in the Rat Basal Nuclei after Acute Hypoxia
    • Abstract: We studied correlations between the intensity of accumulation of oxidatively modified proteins and the state of the system of proteolysis in the basal nuclei (nucl. caudatus, pallidum, nucl. accumbens of the septum, and amygdala) of the rat brain after an episode of intense acute hypobaric hypoxia. We demonstrated that, the processes of protein peroxidation in the basal ganglia are intensified under the action of hypoxia in a parallel manner with increase in proteolytic activity. Accumulation of oxidized proteins is considered a factor influencing the activity of proteolysis.
      PubDate: 2014-12-09
       
  • Effects of Atorvastatin on E-Selectin and Myeloperoxidase Expressions
           after Cerebral Ischemia-Reperfusion Injury in Rats
    • Abstract: We examined expressions of E-selectin and myeloperoxidase (MPO) in cerebral tissues after cerebral ischemia-reperfusion (CIR) in rats and evaluated neuroprotective effects of atorvastatin under these conditions. Immunohistochemical methods were used to detect E-selectin and MPO expression in the tissue. Small numbers of E-selectin- and MPO-positive cells were observed in the sham group within 4 to 24 h time intervals. In the operation group, numerous positive cells were found in the cortex and hippocampus after CIR. E-selectin expression occurred at 4 h, peaked at 12 h, and returned to nearly normal levels at 24 h. However, E-selectin expression in the intervention (CIR + atorvastatin) group was significantly lower than that in the operation group at each time (P < 0.05). Myeloperoxidase had nearly similar timing of changes in E-selectin expression, and MPO expressions at different time points in the intervention group were significantly lower than those in the operation group (P < 0.05). Therefore, expressions of E-selectin and MPO change dynamically after CIR. Atorvastatin, an agent having antiinflammatory properties, demonstrates an obvious protective effect with respect to acute CIR-related damage.
      PubDate: 2014-12-09
       
  • Effects of New Coordination Compounds of Ge, Sn, and Mg on Acute
           Generalized Convulsive Activity in Rats
    • Abstract: Neurotropic effects of new coordination compounds, germacit and stanmacit, were tested on models of acute generalized convulsive activity induced in rats by injections of pentylenetetrazol (PTZ, 40 mg/kg), picrotoxin (PT, 2.0 mg/kg), or kainic acid (KA, 15 mg/kg). The tested biologically active substances were injected in doses corresponding to 1/10, 1/20, 1/40, 1/80, or 1/135 of the calculated LD50. Germacit provided obvious anticonvulsive effects in the case of seizure activity induced by PTZ (in a dose of 1/80 LD50), PT, and KA (in doses of 1/40 LD50); the intensity of convulsive manifestations decreased significantly compared with analogous indices in control groups (P < 0.05). Stanmacit did not influence the expression of acute PT-induced convulsions (P > 0.05) but intensified PTZ- and KA-induced seizures (at 1/20 and 1/40 LD50, respectively; P < 0.05). The obtained data are indicative of the ability of new complex coordination compounds of germanium and tin with magnesium and citric acid to significantly control the excitability of cerebral structures involved in the generation of epileptiform activity.
      PubDate: 2014-12-09
       
  • Protective Actions of Ghrelin on Global Cerebral Ischemia-Induced Memory
           Deficits
    • Abstract: In our study, we investigated transient global cerebral ischemia (TGCI)-induced changes in spatial memory and motor activity together with apoptotic, oxidant, and NO/NOS signaling parameters in rats and the effects of treatment of animals with ghrelin. The TGCI-induced deficiencies of spatial memory and motor activity in the Y-maze and open field tests were attenuated by ghrelin treatment. Furthermore, ghrelin administration lowered the levels of caspase-3 and iNOS elevated by TGCI in the hippocampus. Thus, we conclude that ghrelin exerts a neuroprotective action against hippocampal TGCI injury via influencing apoptotic, oxidant, and/or NO/NOS pathways. If the underlying mechanisms of action of this agent are fully clarified, ghrelin might be a candidate drug for treatment of TGCI-induced memory impairments.
      PubDate: 2014-12-09
       
  • Effect of Injury of the Cortico- and Rubro-Spinal Pathways on Operant
           Food-Procuring Reflexes in Cats
    • Abstract: In experiments on cats with injury of the cortico- and rubro-spinal pathways, we studied the dynamics of recovery of operant (instrumental) food-procuring reactions at different durations of presurgery learning of animals. Operant manipulatory food-procuring movements were realized under conditions of horizontal and vertical tests, which required training for and support of a strictly defined pose in the course of performance of such movements and determined a specific pattern and stability of the coordinated motor phenomenon. The severity of abnormalities of operant food-procuring activity after transection of the lateral funiculus of the spinal cord at the level of С5-С6 and the time interval necessary for compensation of disorders of the developed manipulatory reaction depended significantly on the duration of presurgery motor learning and decreased considerably with increase in this duration. Such increase determined transformation of the pattern of postural rearrangement, which demonstrated no dependence on the amplitude and trajectory of the forthcoming operant phasic movements and was observed under conditions of both horizontal and vertical motor tests. Our results indicate that the main factor providing successful compensation of disorders of the developed operant habit in cats after injury of the cortico- and rubro-spinal pathways is active involvement of the tecto-and reticulo-spinal systems in the process of formation of the reflex. This can be due to an increase in the duration and intensity of presurgery learning of animals.
      PubDate: 2014-12-09
       
  • Biophysical Mechanism of Parasympathetic Excitation of Urinary Bladder
           Smooth Muscle Cells: a Simulation Study
    • Abstract: Using the Hodgkin-Huxley formalism, we developed a computer model of a smooth muscle cell (SMC) of the urinary bladder detrusor; the model included the main types of ion channels and pumps, as well as intracellular calcium regulatory mechanisms inherent in the prototype cell. The biophysical mechanisms of generation of action potentials (APs) necessary for initiation of muscle contraction and those of calcium transients in response to parasympathetic activation of metabotropic М2/М3-cholinoreceptors and co-activation of Р2Х-purinoreceptors were investigated. The simulated SMC in response to a depolarizing current pulse generated an AP that was, by a number of indices, similar to real APs and was also accompanied by a transient elevation of the intracellular calcium concentration. We demonstrated a possibility of generation of such APs in response to a transient increase in the conductivity of channels of calcium-dependent chloride current accompanied by increase in the conductivity of channels associated with Р2Х-receptors (the conductivity ratio was 95 to 5 % and similar to that in the prototype). For the AP generation, temporal relations of the processes of increases in the mentioned conductances simulating the final effect of activation of М2/М3- and Р2Х-receptors were significant. These results obtained on the rather simplified model allow researchers to use the latter as an appropriate starting point for the development of more detailed models (in particular, those representing cascades of metabolic reactions triggered by a parasympathetic action).
      PubDate: 2014-12-09
       
  • Wavelet Decomposition-Based Analysis of Mismatch Negativity Elicited by a
           Multi-Feature Paradigm
    • Abstract: In this study, event-related potentials (ERPs) collected from normally hearing subjects and elicited by a multi-feature paradigm were investigated, and mismatch negativity (MMN) was detected. Standard stimuli and five types of deviant stimuli were presented in a specified sequence, while EEG data were recorded digitally at a 1024 sec–1 sampling rate. Two wavelet analyses were compared with a traditional difference-wave (DW) method. The Reverse biorthogonal wavelet ot the order of 6.8 and the quadratic B-Spline wavelet were applied for seven-level decomposition. The sixth-level approximation coefficients were appropriate for extracting the MMN from the averaged trace. The results obtained showed that wavelet decomposition (WLD) methods extract MMN as well as a band-pass digital filter (DF). The differences of the MMN peak latency between deviant types elicited by B-Spline WLD were more significant than those extracted by the DW, DF, or Reverse biorthogonal WLD. Also, wavelet coefficients of the delta-theta range indicated good discrimination between some combinations of the deviant types.
      PubDate: 2014-12-09
       
  • Roles of Central Monoaminergic Systems in the Formation of Different Types
           of Aggressiveness in Rats
    • Abstract: The contents of noradrenaline, dopamine, and serotonin in the frontal cortex and hippocampus of rats demonstrating dominant, balanced, and submissive types of behavior were examined. The serotonin content in submissive males was considerably lower than that in balanced and dominant animals. The content of noradrenaline was lower in dominant individuals and greater in submissive ones as compared with the analogous index in balanced rats. The content of dopamine in the frontal cortex was lower in both submissive and dominant animals, while that in the hippocampus was lower only in submissive males (in comparison with balanced individuals).
      PubDate: 2014-06-01
       
  • Peculiarities of Utilization of Glucose by Brain Tissues of
           Alcohol-Dependent Rats
    • Abstract: We evaluated the ability of brain tissues of normal and alcohol-dependent rats to utilize glucose under conditions of experimental hyperglycemia; we estimated the arterio-venous difference (AVD) of the glucose levels in the brain (arteria carotis comm. – sinus sagittalis inf.) and compared this index with that in the organism’s tissues in general (samples were taken from the femoral veins, i.e., AVD a. carotis comm. – v. femoralis). Blood samples were taken on an empty stomach and 30 min after glucose loading (0.33 g glucose per 1 kg of the body mass injected i.v. as a 20% solution). In control rats (n = 10), the above-mentioned differences for the brain (AVDb) and for the entire organism (AVDo) were 0.7 ± 0.1 and 0.5 ± 0.1 mM, respectively. In alcohol-dependent animals (n = 10), the respective values were 0.2 ± 0.1 and 0.4 ± 0.1 mM. After glucose loading, the AVDb in control rats was 0.8 ± 0.1 mM (increment 0.1 mM), while the AVDo reached 0.9 ± 0.1 mM (increment 0.4 mM). In alcohol-dependent rats, the analogous values corresponded to 0.2 ± 0.1 mM, (i.e., there was no increase), and 0.7 ± 0.1 mM (increment 0.3 mM). Therefore, the ability of the alcoholized brain to utilize glucose drops significantly. We suppose that decreases in the activity of enzymes providing glycolysis are the main reason for this phenomenon.
      PubDate: 2014-06-01
       
  • Streptozotocin-Induced Diabetes-Related Changes in the Functional State of
           the Rat Retina: Possibilities for Correction Using Delta Sleep-Inducing
           Peptide
    • Abstract: Three months after single injection of streptozotocin (50.0 mg/kg, i.p.), average activities of superoxide dismutase (SOD) and glutathione reductase (GTR) in tissues of the retina of Wistar rats were lower by 47.5 and 42.2%, respectively, while the content of malondialdehyde (MDA) was about 330% of the norm. Recording of electroretinogram (ERG) showed that the amplitude of wave a in these animals was significantly lower (by 57.3%), while the latencies of waves a and b exceeded normal values by 27.5 and 11.8 %, respectively (P < 0.05). After injections of δ sleep-inducing peptide (δSIP, 0.05 mg/kg, i.p., once every three days for two months), SOD and GTR activities did not differ significantly from normal values, while the MDA level was higher by 53.7% (P < 0.05). The mean amplitude of ERG wave a demonstrated no considerable difference from the norm; at the same time, the latencies of waves a and b still exceeded normal values by 13.2 and 10.4 %, respectively. Therefore, negative changes in the functional state of the retina observed because of the development of diabetic retinopathy undergo noticeable moderation under the influence of δSIP.
      PubDate: 2014-06-01
       
  • Vladimir Ganitkevich
    • PubDate: 2014-06-01
       
 
 
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