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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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Mechanisms of activation and modulation of the TRPV1 receptor: relationship between structure and function
Touška, Filip ; Vlachová, Viktorie (advisor) ; Teisinger, Jan (referee)
Vanilloid Receptor Subtype 1 - TRPV1 - is an important member of the TRP ion channel family. The physiological role of this ion channel is to integrate the nociceptive signals from the peripheral nervous system. TRPV1 participates in the detection of noxious stimuli on the primary afferent sensory neurons: of the chemical stimuli, such as capsaicin, resiniferatoxin, inflammatory mediators, endogenous vanilloids, and of the low pH (<6.5), and of the noxious heat stimuli (>43řC). Apart from the high expression on the dorsal root ganglion neurons and trigeminal ganglions, the functional expression of this receptor has been also found in the central nervous system, where its role remains elusive, however. Structural-functional studies which have been carried out since the receptor was first cloned, that is 13 years ago, have revealed several specific characteristics. Nonetheless, a number of questions remain to be answered, particularly those concerning cellular mechanisms and regulation of TRPV1's activation, modulation, and its complex function in the nervous system. The aim of this diploma thesis was to characterize, using electrophysiological and fluorescence techniques, the activation and desensitization kinetics of recombinant TRPV1 receptor in relation to the dynamic changes of intracellular calcium....
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