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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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NMDA receptors in astrocytes: their role in ischemic brain injury
Valný, Martin ; Anděrová, Miroslava (advisor) ; Hock, Miroslav (referee)
Glutamate is the main excitatory neurotransmitter in the mammalian brain, and its transmission is responsible for higher brain functions, such as learning, memory and cognition. Glutamate action is mediated by variety of glutamate receptors, of which N-methyl-D-aspartate (NMDA) receptors are the most remarkable due to their high Ca2+ permeability and complex pharmacology. Despite the widespread expression of NMDA receptors in astroglial cells in different brain regions, they have been studied mostly in neurons. Therefore, the role of astroglial NMDA receptors under physiological conditions as well as in pathological states, such as cerebral ischemia, is not fully understood. The aim of this work was to elucidate the presence, composition and function of these receptors in astrocytes under physiological conditions and after focal cerebral ischemia. For this purpose, we used transgenic (GFAP/EGFP) mice, in which astrocytes express enhanced green fluorescent protein (EGFP) under the control of human promotor for glial fibrillary acidic protein (GFAP) enabling astrocyte isolation and their collection via fluorescence-activated cell sorting. We performed single-cell RT-qPCR analysis of astrocytes isolated from the cortex of adult mice. The analyzed cells were isolated from the uninjured brains of 50...
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NMDA receptors in astrocytes: their role in ischemic brain injury
Valný, Martin ; Anděrová, Miroslava (advisor) ; Hock, Miroslav (referee)
Glutamate is the main excitatory neurotransmitter in the mammalian brain, and its transmission is responsible for higher brain functions, such as learning, memory and cognition. Glutamate action is mediated by variety of glutamate receptors, of which N-methyl-D-aspartate (NMDA) receptors are the most remarkable due to their high Ca2+ permeability and complex pharmacology. Despite the widespread expression of NMDA receptors in astroglial cells in different brain regions, they have been studied mostly in neurons. Therefore, the role of astroglial NMDA receptors under physiological conditions as well as in pathological states, such as cerebral ischemia, is not fully understood. The aim of this work was to elucidate the presence, composition and function of these receptors in astrocytes under physiological conditions and after focal cerebral ischemia. For this purpose, we used transgenic (GFAP/EGFP) mice, in which astrocytes express enhanced green fluorescent protein (EGFP) under the control of human promotor for glial fibrillary acidic protein (GFAP) enabling astrocyte isolation and their collection via fluorescence-activated cell sorting. We performed single-cell RT-qPCR analysis of astrocytes isolated from the cortex of adult mice. The analyzed cells were isolated from the uninjured brains of 50...
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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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