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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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The effect of long-term morphine and its withdrawal on selected signaling proteins in rat heart
Ilková, Karolina ; Novotný, Jiří (advisor) ; Černá, Věra (referee)
Morphine is considered the gold standard among analgesics in the treatment of severe pain due to its effects mediated by μ-opioid receptors. However, it also produces various side effects and poses a high risk of developing tolerance and dependence. The aim of this bachelor thesis is to contribute to the elucidation of the action of morphine at the molecular level in cardiac muscle. Changes of protein levels in key signaling molecules in the signaling cascade induced by morphine administration with increasing doses and subsequent abstinence for 24 hours, 1 month and 3 months were investigated. Specifically, these were adenosine A2b receptor, β2-adrenergic receptor, κ-opioid receptor, G protein subunits, GRK5 kinase, and β-arrestin 2. Data of changes in expression were obtained from cardiac tissue homogenates (left ventricle) by Western blot followed by immunodetection, captured on light-sensitive photofilms, and statistically evaluated by ANOVA. Morphine administration did not lead to statistically significant changes in G protein subunits, β- arrestin 2, GRK5 kinase, adenosine A2b receptor, β2-adrenergic receptor, or κ-opioid receptor in rat heart. Therefore in order to develop better and safer analgesics, there is a high necessity of understanding the underlying molecular mechanisms of morphine...
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The effect of long-term morphine application on clock genes expression in the rat brain
Pačesová, Dominika ; Bendová, Zdeňka (advisor) ; Roubalová, Lenka (referee) ; Polidarová, Lenka (referee)
The circadian and opioid systems are systems involved in maintaining homeostasis in the body. Disruption of the circadian system disturbs the proper timing of physiological processes, which can result in the development or exacerbation of pre-existing pathological conditions, including addiction. One of the factors that can influence the precise synchronization of the circadian system is the use and abuse of opioids. The interrelationship between the circadian and opioid systems is poorly studied. To this end, the present study investigated the effect of morphine and methadone on the rat circadian system in adulthood and during development. The aim of this dissertation was to observe the effect of acute morphine administration on the expression of clock genes in the suprachiasmatic nuclei (SCN) of adult rats, and to investigate the effect of long-term morphine or methadone administration and withdrawal on the expression of clock genes in the SCN and on the activity of the enzyme AA-NAT in the pineal gland of adult rats. Proper development of the circadian clock contributes significantly to the maintenance of health in adulthood and ensures good adaptability of the organism to changes in the external environment. No study to date has focused on examining the effects of opioid administration during...
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Molecular mechanisms of morphine action on the immune system
Zeťková, Anna ; Hejnová, Lucie (advisor) ; Vašek, Daniel (referee)
This paper focuses on the molecular effect of morphine, which is widely used for its analgesic and sedative properties. This makes it an important drug for the treatment of chronic and severe pain. In addition to its positive effects, the long-term administration of morphine in particular has its drawbacks, such as the rapid development of tolerance and dependence on it. Other negative effects include constipation, respiratory stagnation or vomiting. These effects are caused not only by the influence of morphine on nerve cells, but also on other cells of the body. This thesis is primarily concerned with the effect of morphine on microglia, which are not only involved in the immune response in the central nervous system, but also have an effect on pain perception or the development of tolerance. This is one of the main areas of research in the field of opioids, therefore, the aim of this thesis is to summarize the findings on the effect of morphine on microglia, which happens mainly through opioid receptors, toll-like receptors and purinoceptors.
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The effect of morphine withdrawal on G protein-coupled receptors and redox balance in rat brain
Kočárková, Veronika ; Novotný, Jiří (advisor) ; Černá, Barbora (referee)
Although morphine is one of the most effective analgesics available, its long-term use is severely limited by the development of tolerance and dependence. Molecular mechanisms responsible for these effects have been the focus of intensive research for decades aimed at developing safer and more effective pain treatments. The aim of this thesis was to contribute to a better understanding of the molecular actions of morphine, as an understanding of these processes is essential to develop better therapeutic approaches. Using western blot analysis, we investigated the effect of 10-day treatment with increasing doses of morphine and its subsequent withdrawal on key components of opioid signalling in the rat cerebellum and cerebral cortex. Amounts of opioid receptors, various heterotrimeric G protein subunits, GRK3 kinase and β-arrestin 2 were examined. Furthermore, the levels of adenosine A3 receptor and cannabinoid receptor type 1 were detected. Finally, we also investigated the effect of morphine and its withdrawal on oxidative stress markers. Morphine administration resulted in a significant decrease in GRK3 kinase levels in both brain regions, and these changes remained even after withdrawal. However, there was no significant change observed in the content of opioid receptors, different G protein...
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Effect of morphine preconditioning and mKATP channel activity on survival of differentiated SH-SY5Y cell line after oxidative stress
Paluba, Michal ; Hejnová, Lucie (advisor) ; Kolář, David (referee)
Morphine as one of the most effective analgesics has been used in medicine for more than a century. However, morphine is also known for its neuroprotective and cardioprotective effect in ischemic disorders, where it induces increased cellular resistance to oxidative stress. One of the aims of our study was to analyze the effect of chronic morphine treatment on the viability of differentiated cells of the neuroblastoma cell line SH-SY5Y after induction of oxidative stress by tert butyl hydroperoxide (tBHP). However, the detailed mechanism of the protective effect of morphine is still unknown. Current research on this topic, and in particular on morphine-induced preconditioning, has focused much attention on mitochondrial ATP- sensitive potassium channels (mKATPs). There is evidence that morphine, through activation of opioid receptors, mimics the protective effect of ischemic preconditioning precisely through activation of mKATP channels. Modulation of mKATP channel activity is thought to be responsible for the functional state of the mitochondria by altering mitochondrial membrane potential and regulating reactive oxygen species (ROS) production. Thus, the next aim of our work was to reveal the role of mKATP channels in morphine preconditioning and the effect of their activity on cell survival. The...
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Rat gut microbiome composition and metabolic faecal markers upon morphine withdrawal
Mičke, Bianka ; Novotný, Jiří (advisor) ; Pácha, Jiří (referee)
The primary purpose of this pilot study was a long-term monitoring of the gut microbiome composition and fecal markers of metabolism in rats following the completion of 10-day intraperitoneal administration of increasing morphine doses (from 10 to 50 mg/kg/day) and in the corresponding control groups of rats that didn't administrate morphine. This study involved the introduction of new methods for microbiome and metabolome research, statistical evaluation of results and interpretation of data, or hypothesis to explain the effects of morphine on the gut microbiome and fecal metabolome composition compared to the resulting data of similarly oriented studies. The actual experiment was conducted on male Wistar rats aged 2 months and weighing approximately 300 g, which were maintained on a standard chow diet. The analysis and evaluation of the resulting data showed that there were changes in the composition of the gut microbiome and fecal metabolome in the experimental group compared to the control group during the reporting period but the induced changes were rather temporary. Further studies should be performed using a significantly larger experimental and control group as well as higher time series granularity. Keywords: morphine, opioids, withdrawal, gut microbiome, faecal metabolome
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Immunohistochemical analysis of the expression of selected signaling molecules in rat brain: the effect of morphine withdrawal
Přítulová, Eliška ; Novotný, Jiří (advisor) ; Mrózková, Petra (referee)
Morphine is one of the most commonly used analgesics for pain, but its clinical use may be accompanied by the development of tolerance and dependence. Abuse of morphine can then lead to the development of severe withdrawal symptoms. Given the knowledge gathered so far, morphine addiction research often examines the impact on areas of the brain involved in the reward system. The main goal of this work was to investigate the effect of long-term administration of morphine and morphine withdrawal on certain signaling molecules that are related to the molecular action of opioids in selected areas of the rat brain. We focused on the cAMP response element-binding protein (CREB) and its active phosphorylated form (pCREB), as well as on G-protein signaling regulator RGS4. Our results indicated that morphine administration may cause a decrease in CREB expression in the basolateral amygdala in morphine-affected rats. We also found a reduction in CREB phosphorylation in the CA1 region of the hippocampus, possibly due to morphine withdrawal for three months. In this study, we did not observe any statistically significant changes in RGS4 expression in the prefrontal cortex and hippocampus due to morphine administration and subsequent morphine withdrawal. Key words: morphine, dependence, withdrawal, rat brain,...
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Potential role of opioids in neuroprotection
Gebauer, Martin ; Novotný, Jiří (advisor) ; Rudajev, Vladimír (referee)
The opioids have been used by mankind for more than two millennia, but effect and mechanism of their action on the cells has been unveiling in the last few decades. The mechanism itself is often still unknown, but its effect is observed only. There are several groups of opioid receptors which are able to bind opioids. These groups are characterized by their differe nt affinity to opioids, in some cases by their different effects on cells and by their representation in the various areas in the CNS. Thus, the effects induces by these opioid are very different in many cases. This thesis summarizes the current knowledge about coronary heart disease and the potential of opioids for the prevention and their effect during ischemia, also summarizes the effects of morphine on the CNS. During ischemia δ-opioid receptors play a major role, because they inhibit or block the proapoptotic effects of ischemia on many levels. These receptors are also involved in inducing and maintaining the animal hibernation and protect animal's body against very harmful effects of hibernation, e.g lack of oxygen and nutrients. Morphine is opioid which has been used as anesthetic for longest time. It is well-known opioid and it has the most known derivates. This thesis also summarizes most significant effects of morphine on...
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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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