M. B. Shtark

S100, a brain-specific protein: Localization and possible role in the snail nervous system

Immunofluorescence techniques were used to show that S100 is present on the surface of neuronal and glial membranes of Helix pomatia in vitro. By the method of rocket immunoelectrophoresis of aqueous, Trition, and n-pentanol extracts of snail nervous tissue, S100 was demonstrated to be mainly in the membrane fraction. Anti-S100 antiserum inhibited the electrical activity of identified neurons, pointing to a relationship of this protein with ionic channels of the excitable membrane. The effect of anti-S100 antiserum on the membrane was potential dependent and controlled by the Ca2+ concentration.

A Comparison of the Dynamics of S100B, S100A1, and S100A6 mRNA Expression in Hippocampal CA1 Area of Rats during Long-Term Potentiation and after Low-Frequency Stimulation

The interest in tissue- and cell-specific S100 proteins physiological roles in the brain remains high. However, necessary experimental data for the assessment of their dynamics in one of the most important brain activities, its plasticity, is not sufficient. We studied the expression of S100B, S100A1, and S100A6 mRNA in the subfield CA1 of rat hippocampal slices after tetanic and low-frequency stimulation by real-time PCR. Within 30 min after tetanization, a 2–4 fold increase of the S100B mRNA level was observed as compared to the control (intact slices) or to low-frequency stimulation. Subsequently, the S100B mRNA content gradually returned to baseline. The amount of S100A1 mRNA gradually increased during first hour and maintained at the achieved level in the course of second hour after tetanization. The level of S100A6 mRNA did not change following tetanization or low-frequency stimulation.

Regulation of S100B gene in rat hippocampal CA1 area during long term potentiation.

In the present study we investigated the regulation of S100B expression during tetanization-induced hippocampal long term potentiation, one of the best characterized forms of synaptic plasticity. Tetanization resulted in time-dependent change in S100B gene expression and protein content in hippocampal CA1 area. We analyzed the promoter region of the rat S100B gene and identified response elements for the tumor suppressor p53. ChIP assay revealed that p53 could bind to putative p53-binding sites of the S100B promoter. The time-dependent recruitment of p53 to its putative binding sites in the S100B gene promoter paralleled the time-course change of S100B mRNA and protein levels. Thus, these results strongly support the view that S100B gene may be a target of p53. Moreover, we demonstrated that the increase of S100B protein content was accompanied with the decrease of p53 protein content, and it seems that the decrease is regulated on post-translational level. Thus, our results may help to understand the physiological function of the p53-S100B-p53 loop in the process of synaptic plasticity.

Psychotropic drug tenoten activates mitogen-activated MAP/ERK kinase regulatory cascade controlling the neuroprotective effects.

For evaluation of the molecular mechanisms underlying the effects of tenoten, a preparation based on ultralow-dose antibodies to S100 proteins and intended for the therapy of anxious and depressive disorders, we studied its influence on mitogen-activated ERK kinase cascade in Helix lucorum subpharyngeal ganglion complex. Western blot analysis showed that incubation of the ganglion preparation with tenoten resulted in significant activation of mitogen-activated ERK kinases, which was reduced by PD98059 (blocker of upstream protein kinase). This attests to a specific effect of the drug on mitogen-activated ERK kinase cascade. It is hypothesized that the therapeutic efficiency of tenoten is realed to activation of mitogen-activated ERK kinase cascade.

Expression of p53 Target Genes in the Early Phase of Long-Term Potentiation in the Rat Hippocampal CA1 Area

Gene expression plays an important role in the mechanisms of long-term potentiation (LTP), which is a widely accepted experimental model of synaptic plasticity. We have studied the expression of at least 50 genes that are transcriptionally regulated by p53, as well as other genes that are related to p53-dependent processes, in the early phase of LTP. Within 30 min after Schaffer collaterals (SC) tetanization, increases in the mRNA and protein levels of Bax, which are upregulated by p53, and a decrease in the mRNA and protein levels of Bcl2, which are downregulated by p53, were observed. The inhibition of Mdm2 by nutlin-3 increased the basal p53 protein level and rescued its tetanization-induced depletion, which suggested the involvement of Mdm2 in the control over p53 during LTP. Furthermore, nutlin-3 caused an increase in the basal expression of Bax and a decrease in the basal expression of Bcl2, whereas tetanization-induced changes in their expression were occluded. These results support the hypothesis that p53 may be involved in transcriptional regulation during the early phase of LTP. We hope that the presented data may aid in the understanding of the contribution of p53 and related genes in the processes that are associated with synaptic plasticity.

Dynamic Mapping of the Brain in Substance-Dependent Individuals: Functional Magnetic Resonance Imaging

Functional magnetic resonance imaging can be used to study numerous brain dysfunctions, including disorders of the self, in substance-dependent individuals. The self as the sum of human concepts about oneself is regulated by the brain system close to the default mode network: the medial prefrontal cortex, posterior cingulated gyrus, and some parietal regions. However, the composition and activity of this system in mental disease, specifically, in substance addiction, are virtually not described. Our study showed that self-appraisal task in addicts activates the superior frontal cortex, cuneus, precuneus, angular gyrus, and posterior cingulated cortex. The involvement of the parietal (postcentral and supramarginal gyri) and temporal (superior temporal and Heschl’s gyri) sensory areas is diminished. Hence, published data on the involvement of the cingulate cortex and prefrontal cortex in functional regulation of the self are confirmed. Activation-deactivation patterns in the parietal and temporal regions differ significantly from the previous descriptions.

Neuroprotective effect of ultra-low doses of antibodies against S100 protein in neuroblastoma culture during oxygen and glucose deprivation

Antibodies against S100 protein applied in high and ultra-high dilutions possess neuroprotective activity and maintain survival of neuroblastoma C-1300 cells under conditions of oxygen and glucose deprivation. The examined antibody preparations stimulated differentiation in neuroblastoma culture thereby demonstrating pronounced neurotrophic activity.

Sirt1 Regulates p53 Stability and Expression of Its Target S100B during Long-Term Potentiation in Rat Hippocampus

Induction of long-term potentiation in rat hippocampus was followed by short-term activation of transcription factor p53 and its subsequent degradation. We studied the effects of EX-527 (inhibitor of deacetylase Sirt1, a negative regulator of p53) and pifi thrin-β (inhibitor of p53-dependent transcription) on the levels of p53 protein and mRNA of its target gene S100B during long-term potentiation. Pifi thrin-β limited the increase in S100B mRNA content after tetanization, which confi rmed signifi cant contribution of p53 in the regulation of S100B during long-term potentiation. EX-527 completely prevented p53 degradation and increased S100B expression induced by tetanization. Thus, Str1 regulates stability of p53 and expression of its target gene S100B in rat hippocampus during long-term potentiation.

Synergetic fMRI-EEG Brain Mapping in Alpha-Rhythm Voluntary Control Mode

For the first time in neurobiology-related issues, the synergistic spatial dynamics of EEG and fMRI (BOLD phenomenon) was studied during cognitive alpha biofeedback training in the operant conditioning mode (acoustic reinforcement of alpha-rhythm development and stability). Significant changes in alpha-rhythm intensity were found in T6 electrode area (Brodmann area 37). Brodmann areas related to solving alpha-training tasks and maximally involved in the formation of new neuronal network were middle and superior temporal gyri (areas 21, 22, and 37), fusiform gyrus, inferior frontal gyrus (areas 4, 6, and 46), anterior cingulate gyrus (areas 23 and 24), cuneus, and precuneus (area 7). Wide involvement of Brodmann areas is determined by psychological architecture of alpha-rhythm generating system control that includes complex cognitive activities: decision making, retrieval of long-term memory, evaluation of the reward and control efficiency during alpha-EEG biofeedback.

Induction of S100B Gene Expression in Long-Term Potentiation in the Hippocampal CA1 Field Depends on Activity of NMDA Receptors

The effects of NMDA receptor blocker MK-801 on the increase in S100B protein mRNA content induced by long-term posttetanic potentiation in the hippocampal sections were studied. The level of S100B mRNA after 30-min tetanization in the presence of 10 μM MK-801 constituted 132% of the basal level, which was significantly (226%) lower than the control level. Hence, gene expression, induced by long-term posttetanic potentiation, in the glial cells (similarly as in the neurons) depended significantly on NMDA receptors.