National Repository of Grey Literature 49 records found  beginprevious15 - 24nextend  jump to record: Search took 0.01 seconds. 
Membrane Properties of Glial Cells after Ischemia in vivo
Pivoňková, Helena ; Anděrová, Miroslava (advisor) ; Vyklický, Ladislav (referee) ; Vlachová, Viktorie (referee)
In my PhD thesis, I aimed to characterize the membrane properties of astrocytes and NG2 glia during the acute and chronic phases of the ischemic injury in the central nervous system with a focus on the expression and activity of K+ ion channels. Two ischemia models in rats were used for the experiments - global cerebral ischemia 5 causing selective neuronal loss and astrogliosis in the CA1 region of the hippocampus, and incubation of spinal cord segments in a solution with high K+ concentration. We found that hippocampal astrocytes depolarize starting 3 days after ischemia, and demonstrate an increase in the inward rectification of their whole cell currents 1 month after ischemia. The Kir4.1 channel expression in the hippocampal tissue was downregulated starting 3 days after ischemia, while the expression of Kir2.1, Kir5.1 and TREK1 channels was strongly upregulated in reactive astrocytes 1 month after ischemia. NG2 glia displayed a significant increase in the outwardly rectifying delayed and A-type K+ (KDR and KA) currents 2 hours and 3 days after ischemia, and a decrease in the inwardly rectifying K+ currents 3 days after ischemia, a typical current pattern of proliferating cells. Complex astrocytes in the spinal cord pre-incubated in a solution with high [K+] showed the largest changes in their membrane...
Molecular mechanisms of activation and modulation of TRPV3 receptor
Chvojka, Štěpán ; Vlachová, Viktorie (advisor) ; Novotný, Jiří (referee)
Transient receptor potential vanilloid 3 receptor channel (TRPV3) is a thermosensitive ion channel expressed in skin keratinocytes. There, in a molecular complex with the epidermal growth factor receptor (EGFR) contributes to proliferation and terminal differentiation of keratinocytes, temperature detection, pain and pruritus. TRPV3 is activated by a number of exogenous compounds, such as carvacrol from oregano, thymol from thyme and eugenol from clove. Its unique feature is sensitization, TRPV3 channel activity successively increases upon repeated stimulation. The molecular basis of this process is not yet understood. One of the considered possibility is a direct phosphorylation of TRPV3 protein through signaling pathways involving EGFR and mitogen-activated protein kinase MAPK1 / MAPK3 (also called ERK2 / ERK1). In this thesis we investigated whether sensitization of TRPV3 which is expressed in a human cell line immortalized keratinocytes could be influenced by mutations on the predicted consensual phosphorylation sites for MAPK1 / MAPK3. We used electrophysiological patch-clamp technique and tested eight mutants, in which was threonine or serine replaced with aspartic acid mimicking phosphorylation. We identified six residues where the mutations influenced at least one of the functional...
Modulatory mechanisms of nociceptive TRP channels
Maršáková, Lenka ; Vlachová, Viktorie (advisor) ; Novotný, Jiří (referee) ; Zemková, Hana (referee)
Detection of painful stimuli in the periphery is mediated by temperature-sensitive transient receptor potential (TRP) channels which are expressed in primary afferent endings of free sensory neurons called nociceptors. TRP channels in nociceptors are involved in the detection of thermal, but also mechanical and chemical stimuli. Out of seven known types of temperature-sensitive TRP channels, three are responsible for detecting painful temperatures: vanilloid receptors TRPV1 (> 42 o C) and TRPV2 (> 52 o C) detect noxious heat, and ankyrin receptor TRPA1 detects noxious cold (< 17 o C). Better knowledge of TRP channel mechanisms of action is essential for understanding TRP channel functions and ultimately for the design of potential analgesics. New findings presented in this thesis clarify mechanisms of action of TRPV1 and TRPA1 receptors, focusing on camphor and voltage sensitivity of TRPV1 channels and calcium modulation of TRPA1 channels. The first topic discussed in this thesis is the mechanism of camphor sensitivity of TRPV1 receptor. Camphor is a naturally occurring substance known since time immemorial for its effective analgesic properties, yet its mechanism of action is not understood. Camphor is known to be a partial agonist of TRPV1 channel, a full agonist of TRPV3 channel, but also an inhibitor of...
Effects of new quinazoline derivatives on signalling pathways of muscarinic receptors
Nelic, Dominik ; Vlachová, Viktorie (advisor) ; Černá, Věra (referee)
The M2 and M3 subtypes of the muscarinic receptors are involved in smooth muscle contraction in the airways and lungs. Excessive activation of muscarinic receptors is associated with serious diseases such as asthma or chronic obstructive pulmonary disease. Blocking of muscarinic receptors is already utilized in the treatment of these diseases. Long-acting muscarinic antagonists are used as part of the therapy for these diseases simultaneously with anti-inflammatory corticosteroids and agonists of β2-adrenergic receptors, which induce smooth muscle relaxation. The natural substances vasicine and vasicinone isolated from dull plant Malabar nut (Justicia adhatoda) have been historically used to treat lung diseases, where they stimulate smooth muscle relaxation. Based on modifications of their structures, a series of substances with a modified quinazoline skeleton of the original structure vasicinone was prepared. These substances exert bronchodialtional activity on isolated rodent trachea. The aim of this diploma thesis was to confirm that the bronchodilatory effect of four quinazoline derivatives is mediated by the blocking of muscarinic receptors and also clarify in more detail the mechanism of action on muscarinic receptors. For this purpose, binding and functional pharmacological analysis of four...
Incidence and Properties of Thermosensitive TRP Ion Channels in Cellular Models of Sensory Neurones
Loudová, Leona ; Vlachová, Viktorie (advisor) ; Boušová, Kristýna (referee)
Primary afferent sensory neurons enable all living organisms to survive in their environment and react to dangerous stimuli, including noxious and irritant chemicals, temperature, and pressure. These pseudo-unipolar neurons represent a heterologous population that, depending on functional properties, morphology, receptor equipment, degree of myelination, and conduction velocity, determines the intensity at which a stimulus is converted to an electrical signal that is then conducted to the central nervous system to elicit defensive response. The cell bodies of the peripheral sensory neurons are localized in the dorsal root ganglia (DRG) and cell lines derived from these neurons are intensively used not only to study the mechanisms of pain, but also to rationally search for substances with potential analgesic effect. The main goal of this bachelor's thesis is to summarize the current research on molecular mechanisms of nociception using cell lines derived from DRG neurons with a focus on a specific group of temperature-sensitive transient receptor potential (thermoTRP) ion channels. The aim is to present currently available studies focusing on cellular and molecular differences that result from different methodological approaches to the preparation and cultivation of cell cultures, especially in the...
Molecular mechanisms of polymodal regulation of TRPA1 receptor
Sinica, Viktor ; Vlachová, Viktorie (advisor) ; Vondrášek, Jiří (referee) ; Holendová, Blanka (referee)
The TRPA1 channel is a universal, nociception-mediating cellular sensor activated by various environmental irritants, potentially harmful physical modalities and endogenous mediators of pathophysiological processes. The polymodality of TRPA1 channel allows the activation stimuli to further enhance or suppress each other's effect. While this modulation effect has its physiological importance in promoting the protective cellular and behavioral mechanisms, it may result into the unpleasant pain-related effects accompanying the chronical pain caused by aberrant TRPA1 channel activity. In order to effectively and selectively target the synergic properties of TRPA1 modulators, while preserving the sensitivity to the environmental threads, the knowledge of the mechanisms of polymodal regulation at the molecular level are required. This doctoral thesis aims at the elucidation of three main mechanisms of TRPA1 regulation: 1) the regulation via intracellular signaling cascades and phosphorylation, 2) the interaction with membrane phospholipids and 3) the temperature-driven gating. The results presented in the thesis show that the effects of the inflammatory mediator bradykinin are decreased by the low-frequency high-induction electromagnetic field used in magnetotherapy. We have identified a residue S602...
Identification of changes in membrane properties of astrocytes in a mouse model of amyotrophic lateral sclerosis
Vaňátko, Ondřej ; Turečková, Jana (advisor) ; Vlachová, Viktorie (referee)
Amyotrophic lateral sclerosis (ALS) is a progressive neurological disorder of the central nervous system characterized by loss of motor neurons and voluntary muscle degeneration. Astrocytes play a major role in regulation of the disease onset and progression due to their intimate association with neurons. Regulation of ionic homeostasis is one of their key functions and its failure has been linked to several neurological diseases. The aim of this thesis was to explore differences in membrane properties of astrocytes in ALS. To fulfill this aim, a double transgenic mouse strain with ALS-like phenotype and a specific expression of enhanced green fluorescent protein in astrocytes was generated. To phenotype this strain, two sensorimotor tests, wire grid hang test and rotarod test, were conducted. Immunohistochemistry was used to characterize the strain on a cellular level and to explore changes of specific ion channels. Functional properties of astrocytes were explored using the patch clamp technique. The double transgenic strain has the characteristic ALS-like phenotype and is comparable to the original strain with differences in symptom onset and progression between models and sexes. On the cellular level, there are characteristic ALS features, specifically loss of motor neurons and astrogliosis....
Cellular mechanisms of TRPA1 channel regulation
Barvíková, Kristýna ; Vlachová, Viktorie (advisor) ; Hudeček, Jiří (referee)
TRPA1 is a thermosensitive ion channel from the ankyrin subfamily of Transient Receptor Potential (TRP) receptors. These proteins play essential roles in the transduction of wide variety of environmental and endogenous signals. TRPA1, which is abundantly expressed in primary nociceptive neurons, is an important transducer of various noxious and irritant stimuli and is also involved in the detection of temperature changes. Similarly to other TRP channels, TRPA1 is comprised of four subunits, each with six transmembrane segments (S1-S6), flanked by the cytoplasmic N- and C-terminal ends. In native tissues, TRPA1 is supposed to be regulated by multiple phosphorylation sites that underlie TRPA1 activity under physiological and various pathophysiological conditions. Using mutational approach, we predicted and explored the role of potential phosphorylation sites for protein kinase C in TRPA1 functioning. Our results identify candidate residues, at which phosho-mimicking mutations affected the channel's ability to respond to voltage and chemical stimuli, whereas the phospho-null mutations to alanine or glycine did not affect the channel activation. Particularly, we identify the serine 602 within the N-terminal ankyrin repeat domain 16, the substitution of which to aspartate completely abolished the TRPA1...
Cellular and molecular mechanisms of activation of thermally sensitive TRP ion channels
Máčiková, Lucie ; Vlachová, Viktorie (advisor) ; Anděrová, Miroslava (referee) ; Jakubík, Jan (referee)
The transient receptor potential (TRP) are cation channels mostly permeable to both monovalent and divalent cations. ThermoTRP is a specific group of directly thermally activated TRP channels. The vanilloid transient receptor potential 3 (TRPV3) is an ion channel widely expressed in keratinocytes, that is implicated in the regulation of skin homeostasis, thermo- sensing, nociception and development of itch sensation. Our results show the importance of the cytoplasmic inter-subunit interface in the heat sensitivity of TRPV3. As there is a structural analogy within the vanilloid receptors, our hypothesis of the identified important region is supposed to be valid also for other thermally activated TRPV receptors (TRPV1, TRPV2 and TRPV4). We have proved that TRPV3 is a substrate for ERK1/2 protein kinase (kinase regulated by extracellular signal 1 and 2) and we have identified TRPV3 phosphorylation sites that may be direct targets for ERK1/2. Of these residues, threonine 264 has been shown to be the main phosphorylation site responsible for TRPV3 sensitization mediated by ERK kinase. In human keratinocytes, the phosphorylation might be physiologically and pathophysiologically important in processes of TRPV3 sensitization mediated by MAPK signaling pathway. The transient receptor potential ankyrin 1...
Mechanisms of Activation and Modulation of Ion Channels Specific for Nociceptive Neurones
Touška, Filip ; Vlachová, Viktorie (advisor) ; Paleček, Jiří (referee) ; Tureček, Rostislav (referee)
Human body detects potentially damaging stimuli by specialized sensory nerve endings in the skin, the nociceptors. Their membranes are equipped with ion channels, molecular sensors, coding the outside stimuli into the trains of action potentials and conducting them to the higher brain centers. The most prominent group of transduction ion channels is the transient receptor potential (TRP) channel family followed by ion channels responsible for generation and conduction of action potentials from the periphery to the brain, the voltage-gated sodium channels (VGSCs). Understanding the mechanisms how particular stimulus is encoded and processed is of particular importance to find therapeutics for various types of pain conditions. We characterized the properties of VGSC subtypes NaV1.9 and NaV1.8 at high temperatures. We showed that NaV1.9 undergo large increase in current with increasing temperatures and significantly contribute to the action potential generation in dorsal root ganglion (DRG) neurons. Ciguatoxins (CTXs) are sodium channels activator toxins causing ciguatera fish poisoning, a disease manifested by sensory and neurological disturbances. We elucidated the mechanism of CTX- induced cold allodynia, a pathological phenomenon where normally innocuous cool temperatures are perceived as pain. We...

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2 Vlachová, Veronika
5 Vlachová, Vlasta
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