|
|
Role of β-arrestin in μ-opioid and TRPV1 receptor signalling
Nagy Marková, Vendula ; Novotný, Jiří (advisor) ; Blahoš, Jaroslav (referee) ; Roubalová, Lenka (referee)
β-Arrestin belongs to the protein family which has a huge impact not only on GPCR signaling, but its role exceeds the function of the membrane channel, its own signaling cascade, or as a scaffold protein, etc. Here we aimed to study β-arrestin roles on the MOR behaviour in the plasma membrane or -opioid receptor (MOR) signaling and effect on adenylyl cyclase (AC) function using the siRNA to decrease the expression of β-arrestin isoforms. Furthermore, we focused on investigating the role of β-arrestin on the crosstalk between MOR and TRPV1 channels, which are important parts of pain transduction. For this purpose, we used HEK293 cells that stably expressed MOR-YFP or transiently transfected with TRPV1-CFP. We observed that both β-arrestin isoforms have an effect on the lateral mobility of MOR in the plasma membrane and the silencing of one or another β-arrestin isoforms abolishes the effect of MOR agonists to affect its diffusion in the plasma membrane. Interestingly, silencing of β-arrestin1 diminish the internalization of MOR induced by the endogenous agonist endomorphin-2. On the other hand, silencing of β-arrestin2 did not abolish the endomorphin-2 induced MOR internalization. Moreover, both isoforms exhibit a distinct impact on the inhibition of AC induced by the agonists of MOR....
|
|
|
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...
|
|
|
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.
|
|
|
The effect of opioids on the redox state of rat myocardium
Jandová, Gabriela ; Novotný, Jiří (advisor) ; Roubalová, Lenka (referee)
The aim of this work was to study the expression of proteins involved in reactions in which harmful free radicals are degraded in an organism. was observed difference between the expression of selected myocardial proteins in non-influenced animals, animals who were treated with low dosage of morphine (0.1 mg/kg/day or 1 mg/kg/day), and animals administered high dosage of morphine (10 mg/kg/day). Low dosages were administered for 28 days and high dosage for 10 days. In addition, the effect of abstinence lasting one week was assessed after cessation of morphine administration (1 mg/kg/day). Morphine at low dosage (0.1 mg/kg/day) increased levels of glutathion peroxidase-1/2, which may be considered as one of the possible consequences of the ongoing oxidative stress. There were no significant differences in glutathion peroxidase-6 expression. Next aim of this work was to study the expression of antioxidant enzymes. These experiments were carried out on myocardial preparations from the animals treated with a constant dosage of morphine (10 mg/kg/day) for 10 days. Samples from these animals were used for measuring the total antioxidant capacity of the left and right ventricles. These samples were also used for determination of concentration of the oxidative stress marker 8-isoprostane. We also aimed to...
|
|
|
Beta-adrenergic signaling in the rat myocardium under long-term morphine treatment
Moravcová, Radka ; Novotný, Jiří (advisor) ; Roubalová, Lenka (referee)
2. Abstract The aim of this dissertation was to evaluate the effect of low doses (0,1 mg/kg, 1 mg/kg, 1 mg/kg per day for 28 days + 7 days of abstinence) and high doses (10 mg/kg per day for 10 days) of morphine on transmembrane signaling mediated by G-protein coupled receptors (GPCRs) in the rat myocardium. Opioid receptors (OR) and mainly β-adrenergic receptors (β-AR) belong to the most important receptors of this receptor family. δ-OR and κ-OR are the most numerous OR in the myocardium. Results of the present work indicated that there are no significant changes in the expression of these two receptor subtypes after any studied doses of morphine. There are three subtypes of β-AR (β1-AR, β2-AR and β3-AR) represent in the myocardial tissue. Here we studied the expression of β1-AR and β2-AR, because these two major subtypes of β-AR regulate through their signaling pathways functioning of the cardiovascular system. Our immunoblot analysis did not reveal any changes in the expression of β1-AR, but the expression of β2-AR was significantly decreased after treatment with morphine at the dose of 10 mg/kg for the 10 days. More sensitive saturation binding experiments with the nonselective β-antagonist [3 H]CGP 12177 indicated a significant increase in specific binding after treatment with morphine (1 mg/kg/day for...
|
|
|
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.
|
|
|
The effect of morphine on expression and distribution of the alpha and beta subunits of trimeric G-proteins in the rat myocardium
Bartoňová, Iveta ; Novotný, Jiří (advisor) ; Roubalová, Lenka (referee)
Morphine is a clinically very important drug from the opioid group that is used for treatment of severe pain because of its strong analgetic effect. Opioid receptors mediating the morphine effect interact with the Gi/o class of trimeric G-proteins. Opioid receptors also occur in heart tissue and morphine can thus potentially exercise its effect on the function of this organ. The major aim of this project was to pursue consequences of long-term treatment with morphine on expression and distribution of selected heterotrimeric G-protein subunits in the rat heart. Potential cardioprotective effects of this drug have also been studied. Laboratory rats of the Wistar strain were treated with morphine (1 mg/kg/day or 10 mg/kg/day) for 10 or 28 days. The control group was treated with saline solution. Prolonged treatment with morphine did not cause any effects on Gs, Gi, Gz, Gq/11, G subunits, but the expression of Go rather decreased. The results of subsequent experiments showed that prolonged administration of high doses of morphine may reduce the area affected by infarction and reduced the frequency of ventricle arrhythmias depending on dose and duration of morphine administration. Key words: morphine, myocardium, opioid receptor, G-protein subunits, infarction.
|
|
|
Effect of long-term application of morphine on opioid receptors in rat brain cortex
Jeřábková, Kateřina ; Hejnová, Lucie (advisor) ; Roubalová, Lenka (referee)
-5- ABSTRACT A huge effort has been put in determining the mechanism of the development of tolerance and dependence in context of clinical use of morphine for treatment of severe pain. Understanding of this mechanism would help to design new and more efficient pharmaceuticals. This diploma paper discus the opiate receptors with a special focus on long-term effect of chronic morphine treatment, which was determined using a radioligand binding assays with a non-selective antagonist [3 H]Diprenorphine. One of the goals of this work was to create and optimise a method for preparation of pure plasma membranes from rat cortex using percoll gradient. There were five groups, which differed in the length of morphine treatment: ten days (M-10), twenty-eight days (M-28), ten days with seven days of regression (RM-10 twenty-eight days with seven days of regression (RM-28) and a control group (K). The loss of total opioid receptor number was noticeable after ten days and grew slightly during continuous morphine treatment and kept lowering in the period of regression. The total loss was approximately 30% of the control binding. The equilibrium dissociation constant (Kd), thus the affinity of [3 H]Diprenorphine wasn't significantly different among the groups. Morphine acts through µ-opioid receptor, that's why there was a...
|
|
| |
|
| |
guest ::
RSS feed.