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Exploring the role of opioid signaling in modulation of microglial function
Mali, Akash Shivling ; Novotný, Jiří (advisor) ; Svoboda, Petr (referee) ; Machová Urdzíková, Lucia (referee)
Microglial activation is the most important component of neuroinflammation. It appears that opioids may affect microglial M1/M2 polarization in different ways depending on the type of receptor employed. In addition to opioid receptors, Toll-like receptor 4 (TLR4) of the innate immune system can also be activated by some opioid ligands and thus elicit specific cellular responses. Although opioid receptors (ORs) are known to regulate neurotransmission in various peptidergic neurons, their potential role in modulation of microglial function remains largely unknown. In this study, we investigated the effects of OR agonists, namely DAMGO, DADLE, and U-50488, on polarization and metabolic modulation of C8-B4 microglial cells. Our findings have revealed that opioids effectively suppress lipopolysaccharide (LPS)-triggered M1 polarization and promote the M2 polarization state. This was evidenced by decreased phagocytic activity, decreased production of nitric oxide (NO), diminished expression of proinflammatory cytokines such as TNF-α, IL-1β, IL-6, IL-86, and IL-12 beta p40, along with an increased migration rate and elevated expression of anti-inflammatory markers such as IL-4, IL-10, IL-13 arginase 1, and CD206 in microglia compared to cells influenced by LPS. Furthermore, we have demonstrated that...
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Determination of opioid receptors in cerebral cortex of rats exposed to multifunctional opioid peptides
Kusová, Pavla ; Svoboda, Petr (advisor) ; Novotný, Jiří (referee)
The subject of this bachelor thesis was to study the effects of multifunctional peptides LYS739 and LYS744 on the amount of µ-, δ-, ĸ-opioid receptors (µ-OR, δ-OR, ĸ-OR) in rat cortex. Peptides were administered by the dose of 10 mg/kg for seven days. The reference group was administered a dose of 10 mg/kg morphine for the same period of the time. The effect of morphine is mainly through µ-OR. Long-term exposure to this opioid agonist results in a reduction in the function and quantity of these receptors in the development of tolerance and dependence. Multifunctional opioid peptides have begun to be investigated for their therapeutic potential to reduce adverse effects and increase efficacy. Their potential lies in their ability to interact with multiple opioid receptors. Peptides LYS739 and LYS744 act as agonists of µ-OR, δ-OR and simultaneously as antagonists of ĸ-OR. The amount of opioid receptors was determined by SDS-PAGE followed by Western blot. The results were compared with a control group that was administered by saline and a reference group that was administered by morphine. There was almost no change in the δ-OR, ĸ-OR receptors. In the case of µ-OR, there was a decrease in morphine and LYS739, but this change was not assessed as statistically significant.
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Effect of morphine on the resistance of the heart to ischemia
Mošovská, Linda ; Neckář, Jan (advisor) ; Žurmanová, Jitka (referee)
2. Abstract Opioids are considered as dangerous and addictive substances, mainly due to synthetic opioids such as heroin. It was discovered, that these substances can play an important role in myocardial ischemia because they can limit the damage of the heart tissue that occurs during a heart attack. Since that heart attack is the most common cardiovascular disease, the protective effect is significant. Cardioprotective effect is mainly mediated through δ opioid receptors, but the few studies have shown cardioprotective effect mediated through κ opioid receptors. The protective effect occurs by activation of opioid receptors by their agonists (eg. morphine or TAN-67), either before ischemia (opioid preconditioning) or before reperfusion (opioid postconditioning). The signaling pathway of cardioprotection include mitochondrial KATP channel, Gi/o proteins, protein kinase C, tyrosine kinases and reactive oxygen species.
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Effect of chronic morphine treatment of rats on myocardial signaling systems regulated by trimeric G-proteins
Škrabalová, Jitka ; Novotný, Jiří (advisor) ; Rudajev, Vladimír (referee)
It has recently been discovered that the effect of morphine can significantly reduce the tissue damage that occurs during myocardial ischemia. The molecular mechanisms by which morphine acts on the heart are still little understood. The aim of this thesis was to monitor the effect of chronic 27-day and 10-day administration of low (1 mg/kg/day) and high (10 mg/kg/ day) doses of morphine on the expression of selected G-protein-coupled receptors (GPCR) and on the expression and activity of adenylyl cyclase (AC). Chronic (27 days) morphine treatment reduced the expression of к-opioids receptors, but 10-day morphine exposure did not influence the expression of these receptors. Assessment of β1- and β2-AR by immunoblot technique did not show any significant change in the expression, but the more accurate determination of β-AR expression using the saturation binding studies revealed that 27-day treatment with high doses of morphine appreciable increased the total number of these receptors. Administration of high doses of morphine led to marked up-regulation of adenylyl cyclase (AC) isoforms V/VI, and the amount of AC decreased proportionally with the time of discontinuation of morphine administration. Low doses of morphine up- regulated AC only during 27-day administration. Chronic morphine exposure did...
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Importance of particular regions of CNS in the development of opioid addiction
Vyvadilová, Tereza ; Hejnová, Lucie (advisor) ; Roubalová, Lenka (referee)
Opiods are used as the most powerful painkillers in the medicine. The mechanism of their effect is determined by binding to the opioids receptors located in the central nervous system and peripheral nervous system. The opioids have high potential to develop addiction. Significance of psychical addiction belongs to losing control above using and compulsive desire to obtain drug of abuse to achieve certain psychical state. The somatic part is increase tolerance demonstrating need of dose increasing to achieve required effect. This thesis summarizes knowledge about particular regions of the central nervous system which participate on developing of addiction as ventral tegmental area, nucleus accumbens, locus coeruleus, ventral pallidum and amygdala. It seems that main role in developing of addiction acts the mesolimbic reward system which relates with increased release of dopamine resulting in stimulation of the brain reward system.
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Molecular physiology of opioid receptors
Valný, Martin ; Novotný, Jiří (advisor) ; Hejnová, Lucie (referee)
The opioid receptors (OR) belong to the family of G protein-coupled receptors (GPCRs). ORs mediate the effects of the opioids, leading primarily to inhibition of neuroexcitability, predominantly through the class of the inhibitory G proteins Gi/Go. Cloning of ORs confirmed the existence of four subtypes of ORs, which mediate effects of different classes of opioid ligands. The major aim of this work is to summarize the current knowledge about characteristics and function of ORs at the molecular level. Acute exposition of ORs to their agonists results in activation of the signaling cascades that trigger mechanisms leading to analgesia. Chronic exposition of ORs to their agonists leads to desensitization and internalization of the receptors and induces adaptive changes in signal transduction system that suppresses the opioid action, and may result in the development of opioid tolerance and dependence. Although a big progress has been made in the field of understanding the molecular mechanisms of the OR-mediated signaling, there are still a lot of unresolved questions that are necessary to answer.
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Study of opioid receptors
Cechová, Kristína ; Hudeček, Jiří (advisor) ; Holáň, Vladimír (referee)
1 ABSTRACT In this Thesis, we studied properties of μ-, δ-, and κ-opioid receptors in lymphocytes isolated from rat spleen. This splenocytes were exposed to mitogen concanavalin A or opiate morphine and cultivated for 48 hours. Under physiological conditions, level of opioid receptors in immune cells is very low. Due to various factors such as presence of opioids, mitogens, long-term exposition to stress, expression of these receptors can be amplified. In this study we demonstrated, that concanavalin A causes up-regulation of μ-, δ- and κ-opioid receptors in lymphocytes isolated from rat spleen. In control cells no significant signal of μ- or δ-receptors was observed. In contrast, κ-opioid receptors were detected already in control cells. Concanavalin A stimulation caused a 2.4 - fold increase of these receptors. In lymphocytes treated with morphine only μ-opioid receptors were up-regulated, whereas in control cells, there was no signal for these receptor type. δ-opioid receptors were not detected in control or morphine treated cells. κ-opioid receptors were determined in control and also in morphine affected lymphocytes but the amount of these receptors wasn't changed by morphine. Detection of μ-, δ- and κ-opioid receptors using Western blot technique in lymphocytes isolated from rat spleen, that were...
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Role of glutamatergic transmission in mechanisms of addiction to morphine.
Moutelíková, Karolína ; Hejnová, Lucie (advisor) ; Červená, Kateřina (referee)
Drugs are used by mankind since ancient times. One group of these substances are opioids. Opioids have antinociceptive effects and can induce euphoria and relaxation as well. A chronic usage of opioids can lead to a development of drug addiction and phenomens like tolerance and sensitization. One of the most used opioids in medicine is morphine. Morphine is isolated from opium of poppy (Papaver somniferum). Direct effect of morphine is mediated via activation of μ- opioid receptors and their signal cascade. It was implicated that the usage of morphine affects other neurotransmmiter systems in the brain and these neurotransmmiter systems play a signifikant role in the development of addiction and other phenomena. One of these systems is an important excitatory brain system - glutamergic system. This bacherol thesis focuses on interrelationship between opioid and glutamatergic systems during addiction.There were described changes in a composition of glutame ionotropic receptors and changes in their expression as well as in expression of metabotropic glutamate receptors. These changes differ in various parts of the brain and in diverse stages of addiction on morphine too. In spite of all diferences, the results of studies indicate that glutamatergic receptors play a significant role in the development...
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Influence of opioid receptor genetic polymorphism on drug addiction.
Syrová, Kateřina ; Hejnová, Lucie (advisor) ; Brejchová, Jana (referee)
Opioid substances have been used by mankind for several millenia not only for their ability to abolish even very intensive states of pain, but also for their ability to stimulate the brain reward circuit. However, a strong addiction can be formed to opioids quickly. This thesis focuses on collecting knowledge about the most abundant polymorphisms of these genes, their physiological impact and potential influence on drug addiction. Key words: opioid receptors, drug addiction, genetic polymorphism
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Specifics of the use of opioids as important immunomodulators in the treatment of pain
Švubová, Veronika ; Hejnová, Lucie (advisor) ; Vašek, Daniel (referee)
This work deals with the specifics associated with the use of opioid analgesics in pain relief. In terms of antinociceptive effects, opioids have not yet been surpassed by other available drugs. However the use of these analgesics is quite problematic in many respects. For over 30 years, studies have shown that opioids can adversely affect components of the immune system (IS) and thus the overall condition of the patient. To understand the relationship between opioids and IS, it is necessary to know the mechanisms leading to immunomodulatory processes. Contact with opioids occurs at the cellular interface through interactions with opioid receptors (ORs). Within IS, we encounter all three basic types of OR - μ (MOR), δ (DOR), κ (KOR) and non-classical nociceptin receptors (NOP). Stimulation of these receptors induces activation of signaling cascades in target cells which can lead to dysregulation of cellular processes, thus modulating the immune response. However, the effect of opioids on IS cells may not be exclusively direct. More complex regulatory pathways have been found, involving parts of the central nervous system (CNS), the sympathetic nervous system (SNS), and endocrine-active tissues. Activation of these pathways then affects the activity of whole lymphoid organs. Each cell type within an...
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