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Modulatory effect of monovalent ions on δ-opioid receptors
Vošahlíková, Miroslava ; Svoboda, Petr (advisor) ; Jakubík, Jan (referee) ; Kršiak, Miloslav (referee)
The exact role of opioid receptors in drug addiction and modulatory mechanism of action of monovalent cations on these receptors are still not fully understood. Our results support the view that the mechanism of addiction to morphine is primarily based on desensitization of μ- and δ-opioid receptors. Desenzitization of agonist response proceeds already at the level of G protein functional activity. Long-term exposure of rats to morphine resulted in increase of number of δ-opioid receptors and change of their sensitivity to sodium ions. Analysis of the effect of different monovalent ions on agonist binding in δ-OR- Gi1α (Cys351 -Ile351 )-HEK293 cell line confirmed the preferential sensitivity of δ-opioid receptor to sodium ions. We have distinguished the high- and low-affinity Na+ sites. Biophysical analysis of interaction of lithium, sodium, potassium and cesium ions with plasma membranes isolated from HEK293 cells with the help of fluorescent probes indicated that monovalent ions interact, in low-affinity manner, with the polar, membrane-water interface of membrane bilayer. Key words: morphine, forebrain cortex, opioid receptors, G proteins, monovalent ions, plasma membrane, fluorescence spectroscopy.
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Trimeric G protein-regulated signaling in neurodegenerative processes
Daňková, Karolína ; Novotný, Jiří (advisor) ; Weissová, Romana (referee)
Members of the large family of G proteins and their coupled receptors are involved in a variety of transduction processes the cell uses to respond to a received signal. Depending on their specific structure and function, they influence a wide range of effector molecules. A large body of research has shown that many neurodegenerative diseases have a negative impact on the signal pathways controlled by G proteins. Due to ageing population, neurodegenerative diseases are currently imposing a risk for growing numbers of people. The sequelae observed in the pathological development of such diseases include especially changes in membrane receptors representation or receptor uncoupling from G protein, which inhibits G subunits activation. The undesirable inhibition or over-stimulation of G proteins results in the increase or decrease in effector activity, which subsequently impacts the production of second messengers and the activity of subsequent members of the signal cascade. As a result, these alterations lead to an increase in intracellular concentration of Ca2+ ions, which then influence receptors responsible for excitotoxicity, and contribute to apoptosis and necrosis of neuronal population. The thesis summarizes the defects of signalling pathways controlled by trimeric G proteins in association...
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The role of cannabinoid signaling in neuroprotection
Mádrová, Eliška ; Novotný, Jiří (advisor) ; Červená, Kateřina (referee)
The name of the endocannabinoid system comes from Cannabis sativa which contains Δ9 -THC that causes psychotropic effects through cannabinoid receptors. It was discovered that Δ9 -THC is not the only ligand of the cannabinoid system but there also naturally exist endogenous cannabinoids in the human body. The main endogenous cannabinoids are anandamide and 2-arachidonoylglycerol which act on various receptors, primarily cannabinoid receptors CB1 and CB2 that fall into a group of G-protein coupled receptors, but they may also affect vanilloid receptor TRPV1 or nuclear peroxisome proliferator-activated receptor PPARγ. By studying the cannabinoid system, it was discovered that cannabinoids can modulate some of the cellular processes such as cell growth, proliferation and differentiation of cells, apoptosis and intracellular concentration of Ca2+ . Recently they have been primarily studied for their usefulness in the treatment of neurodegenerative diseases, for example, Alzheimer's disease, multiple sclerosis or epilepsy because it has been shown that they support the survival of neurons during excitotoxicity and they modulate the release of cytokines responsible for the regulation of the immune system and inflammatory response. Key words: cannabinoid receptors, G proteins, neuroprotection, Δ9 -THC,...
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The effect of morphine withdrawal on the adenylyl cylclase signaling system in rat brain
Nováková, Daniela ; Novotný, Jiří (advisor) ; Rudajev, Vladimír (referee)
The aim of this bachelor thesis is to study the effect of morphine withdrawal on the adenylyl cyclase signal system in the rat brain. Theoretical part of this thesis summarizes basic information known about opioids and its leading representative morphine, molecular mechanisms of its effect on the organism and yet determined knowledge about effects of morphine addiction and subsequent withdrawal on the organism and above all on the central nervous system. There is still much unknown about exact mechanism of development of morphine addiction and withdrawal. This thesis also summarizes briefly the Western blot method used in analysing the effect of morphine withdrawal on selected proteins of the adenylyl cyclase signal system in the rat brain. Experimental part of this thesis is based on the detection of expression of key components of the adenylyl cyclase pathway in selected regions of the rat brain after long-term administration and subsequent withdrawal of increasing doses of morphine. Results of this study did not reveal statistically significant differences in the expression of adenylyl cyclase signaling system components between the withdrawal and the corresponding control groups of animals, confirming high ability of the organism to withstand morphine administration and to return to...
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Lipid rafts and their role in transmembrane signaling mediated by G protein-coupled receptors
Ševčíková, Adéla ; Novotný, Jiří (advisor) ; Funda, Jiří (referee)
Membrane microdomains enriched in cholesterol and sphingolipids, known as lipid rafts and caveolae, contribute to many cellular processes including cholesterol homeostasis or lateral segregation of membrane proteins. This bachelor thesis describes the role of these membrane microdomains on transmembrane signaling mediated by G protein-coupled receptors. This is the most numerous and diverse family of receptors in mammalian cells that can affect a large number of physiological functions of the organism. A large amount of GPCR located in the membrane microdomains that concentrate specific signal components increase the variability of signaling. This issue is very complicated because the methods used to characterize these variable structures have limitations and each of the receptors exhibits specific behaviour. Key words: GPCRs, G proteins, lipid rafts, caveolae, transmembrane signaling
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Modulatory effect of monovalent ions on δ-opioid receptors
Vošahlíková, Miroslava ; Svoboda, Petr (advisor) ; Jakubík, Jan (referee) ; Kršiak, Miloslav (referee)
The exact role of opioid receptors in drug addiction and modulatory mechanism of action of monovalent cations on these receptors are still not fully understood. Our results support the view that the mechanism of addiction to morphine is primarily based on desensitization of μ- and δ-opioid receptors. Desenzitization of agonist response proceeds already at the level of G protein functional activity. Long-term exposure of rats to morphine resulted in increase of number of δ-opioid receptors and change of their sensitivity to sodium ions. Analysis of the effect of different monovalent ions on agonist binding in δ-OR- Gi1α (Cys351 -Ile351 )-HEK293 cell line confirmed the preferential sensitivity of δ-opioid receptor to sodium ions. We have distinguished the high- and low-affinity Na+ sites. Biophysical analysis of interaction of lithium, sodium, potassium and cesium ions with plasma membranes isolated from HEK293 cells with the help of fluorescent probes indicated that monovalent ions interact, in low-affinity manner, with the polar, membrane-water interface of membrane bilayer. Key words: morphine, forebrain cortex, opioid receptors, G proteins, monovalent ions, plasma membrane, fluorescence spectroscopy.
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Cannabinoid signalling and its physiological significance
Pavluch, Vojtěch ; Novotný, Jiří (advisor) ; Moravcová, Simona (referee)
Lidská společnost je ve styku s kanabinoidními látkami již od starověku. Ať už lidé využívali rostlinnou biomasu nebo bylinné léčitelství, bylo konopí vždy předmětem diskuzí. Poznatky objasňující molekulární principy účinku látek obsažených přírodně jen v konopí jsou však známy jen několik málo desítek let. Cílem této práce je charakterizovat subtypy receptorů, na které se kanabinoidy vážou, molekulární mechanismy jejich působení, následné konsekvence ve fyziologii a také poukázat na potenciální uplatnění jak rostlinných, tak syntetických kanabinoidů v lékařství. Kanabinoidní receptory jsou hojně se vyskytující podskupinou integrálních membránových receptorů, spadající do velké rodiny receptorů spřažených s G-proteiny. Vzhledem k ubikviternímu výskytu v organismu tyto receptory po aktivaci příslušnými lipofilními ligandy ovlivňují celou škálu fyziologických pochodů. Vazba kanabinoidních látek na daný subtyp těchto receptorů spouští specifickou signální kaskádu v buňce a ovlivňuje tak určitým způsobem buněčný metabolismus. Studium kanabinoidních receptorů a jejich ligandů přispívá k porozumění procesům zahrnujícím tvorbu paměti a učení, ale také mechanismům zapojeným v analgézii, imunomodulaci a buněčné proliferaci. Tyto receptory však ovlivňují také fyziologii kardiovaskulárního systému nebo...
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