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Effect of ketamine on light-induced changes in the circadian system
Kratina, Alex ; Bendová, Zdeňka (advisor) ; Valeš, Karel (referee)
The circadian system is controlled by the suprachiasmatic nuclei of the hypothalamus (SCN) and ensures optimal timing of physiological processes. Synchronization of this system with external light conditions is based on the activation of NMDA receptors during light exposure in the subjective night. Ketamine is a non-competitive antagonist of NMDA receptors used as a safe anesthetic, whose subanesthetic doses act as an antidepressant with a rapid onset of action, and increase proliferation in some parts of the brain. There are hypotheses about the possible effect of subanesthetic doses of ketamine on the circadian system, altough this effect has not yet been tested. This work aims to investigate the effect of a single subanesthetic dose of ketamine on the circadian system of the rat, especially on light-induced changes in locomotor activity and light-induced markers in the SCN and dentate gyrus, which represents one of the strongly proliferative areas of the brain. Our results show that ketamine decreases light pulse-induced c-FOS protein expression in the SCN at the onset of the subjective night, but increases this expression in the dentate gyrus under the same conditions. Reduction of c-FOS expression in the SCN correlates with the behavioral output of the circadian system and thus suppresses the...
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The study of functional and pharmacological properties of glutamate receptors
Kysilov, Bohdan ; Vyklický, Ladislav (advisor) ; Valeš, Karel (referee) ; Novotný, Jiří (referee)
N-methyl-D-Aspartate receptors (NMDAR) are ionotropic glutamate receptors that are involved in the regulation of nearly every process in the brain. Therefore, even a subtle disturbance in NMDAR function may result in severe pathological consequences. Loss-of- function mutations in the NMDAR-encoding genes have been implicated in numerous neuropsychiatric disorders, including intellectual disability, developmental delay, schizophrenia, autism spectrum disorders, epilepsy, and movement disorders. Insufficient NMDAR function can be rectified by positive allosteric modulators, including neurosteroids; however, the mechanism underlying the potentiating effect of steroids is not well understood. By employing patch-clamp electrophysiology we assessed the effect of newly synthesized neurosteroid-like pregnane analogues on recombinant GluN1/GluN2B receptors. We demonstrated that compounds with short C3 residues, such as pregnanolone acetate (PA- Ace) and pregnanolone carboxylate (PA-Car), are negative modulators of NMDAR, whereas compounds with longer C3 residues, such as pregnanolone butyrate (PA-But) and epipregnanolone butyrate (EPA-But), are positive modulators of NMDARs. Furthermore, we revealed that EPA-But has a disuse-dependent positive allosteric effect, being similar in that regard to endogenous...
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Characterization of the effect of pregnanolone sulfate and its derivatives on NMDA receptors.
Švehla, Pavel ; Vyklický, Ladislav (advisor) ; Blahoš, Jaroslav (referee)
N-methyl-D-aspartate (NMDA) receptors are a subtype of receptors for major excitatory neurotransmitter glutamate in the central nervous system. Their activity is regulated by variety of allosteric modulators, including endogenous neurosteroids and their synthetic analogues. NMDAreceptor dysfunction is implicated in various forms of neurodegeneration and inhibitory neurosteroids have unique therapeutic potential to act as neuroprotective agens. The aim of this work is to investigate relationship between structure and function of neurosteroids with modifications in the D-ring region, using whole-cell patch clamp recording at recombinant GluN1/GluN2B receptors. In this work, we characterised inhibition effect of 19 neurosteroid analogues on NMDA receptor activity and found several of them to be potent NMDA receptor inhibitors. According to our results, there is a linear relationship of IC50 and lipophilicity of a neurosteroid compound, suggesting the plasma membrane plays an important role in neurosteroid access to NMDA receptor. Indeed, using capacitance recording configuration in combination with amphipathic molecule gamma-cyclodextrin, we were able to separate the kinetic of neurosteroid membrane binding from receptor binding. Moreover, these experiments showed that neurosteroid accumulation in the...
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Ionotropic glutamate receptors and excitotoxicity
Skřenková, Kristýna ; Vyklický, Ladislav (advisor) ; Moravec, Jan (referee)
Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system and its excitatory role is mediated trough activation of glutamatergic ionotropic receptors which are responsible for synaptic transmission and play an important role in learning and memory formation. However, excessive exposure to glutamate can result in excitotoxicity which may lead to cell death. The following text is focused on one group of glutamate receptors - NMDA receptors. The study of the receptors is in the centre of current neurobiology research because there is a series of experimental and clinical evidences that they directly participate in the development of serious diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease and may cause neuronal damage in trauma, hypoxia and embolia. The aim of this bachelor thesis is to give a brief overview of current knowledge about the structure and function of NMDA receptors and mechanisms of their activation which leads to excitotoxicity and related neuroprotection.
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Neurobiology of hypoxic-ischemic insult in immature brain
Kuchtiak, Viktor ; Valeš, Karel (advisor) ; Hejnová, Lucie (referee)
Pathology of the hypoxic-ischemic insult is very well described in the adult age, whereas the state of knowledge is largely neglected during the perinatal age. Serious insult in the early postnatal age leads often to the permanent neurological consequences or death. Ischemic insult causes over release of the glutamate in a brain tissue. This process is followed by excitotoxic damage of the tissue. Glutamatergic NMDA receptors play a key role in the excitotoxicity. Over-activated NMDA receptors are one of the possible therapeutic approaches against ischemic damage of the brain. Speaking of contemporary projects focusing on perinatal stroke, it is necessary to take into account developmental differences in the brain tissue and the requirements to minimal toxicity of possible drugs. Pharmacotherapies for hypoxic-ischemic damage implemented in the current perinatology are insufficients.
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Neurobiology of hypoxic-ischemic insult in immature brain
Kuchtiak, Viktor ; Valeš, Karel (advisor) ; Hahnová, Klára (referee)
Pathology of the hypoxic-ischemic insult is very well described in the adult age, whereas the state of knowledge is largely neglected during the perinatal age. Serious insult in the early postnatal age leads often to the permanent neurological consequences or death. Ischemic insult causes over release of the glutamate in a brain tissue. This process is followed by excitotoxic damage of the tissue. Glutamatergic NMDA receptors play a key role in the excitotoxicity. Over-activated NMDA receptors are one of the possible therapeutic approaches against ischemic damage of the brain. Speaking of contemporary projects focusing on perinatal stroke, it is necessary to take into account developmental differences in the brain tissue and the requirements to minimal toxicity of possible drugs. Pharmacotherapies for hypoxic-ischemic damage implemented in the current perinatology are insufficients.
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Animal models of schizophrenia based on NMDA receptors
Svojanovská, Markéta ; Stuchlík, Aleš (advisor) ; Bendová, Zdeňka (referee)
Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system responsible for information processing including learning and memory. Its concentration must be maintained at the correct physiological levels because a deficiency or an excess of glutamate can cause variety of disruptions of CNS function. Glutamate acts also via the NMDA receptor, a specific type of ionotropic glutamate receptor. A number of studies have suggested that glutamatergic NMDA receptors play an important role in an ability to learn, memory, brain development and brain function. Importantly, their reduced function is considered as a possible factor for the pathogenesis of schizophrenia. The NMDA receptor hypofunction hypothesis settles on findings that non-competitive NMDA receptor antagonists such as ketamine, phencyclidine and dizocilpine (MK-801) can induce schizophrenic-like symptoms in healthy individuals and exacerbates symptoms in schizophrenic patients; therefore they are often used in animals to induce schizophrenia-like behavior. All these animal models contribute to a better understanding of the etiology and pathophysiology of schizophrenia and may serve as a useful tool in searching for new antipsychotic agents. Key words: glutamate, schizophrenia, memory, NMDA receptors,...
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Characterization of the effect of pregnanolone sulfate and its derivatives on NMDA receptors.
Švehla, Pavel ; Vyklický, Ladislav (advisor) ; Blahoš, Jaroslav (referee)
N-methyl-D-aspartate (NMDA) receptors are a subtype of receptors for major excitatory neurotransmitter glutamate in the central nervous system. Their activity is regulated by variety of allosteric modulators, including endogenous neurosteroids and their synthetic analogues. NMDAreceptor dysfunction is implicated in various forms of neurodegeneration and inhibitory neurosteroids have unique therapeutic potential to act as neuroprotective agens. The aim of this work is to investigate relationship between structure and function of neurosteroids with modifications in the D-ring region, using whole-cell patch clamp recording at recombinant GluN1/GluN2B receptors. In this work, we characterised inhibition effect of 19 neurosteroid analogues on NMDA receptor activity and found several of them to be potent NMDA receptor inhibitors. According to our results, there is a linear relationship of IC50 and lipophilicity of a neurosteroid compound, suggesting the plasma membrane plays an important role in neurosteroid access to NMDA receptor. Indeed, using capacitance recording configuration in combination with amphipathic molecule gamma-cyclodextrin, we were able to separate the kinetic of neurosteroid membrane binding from receptor binding. Moreover, these experiments showed that neurosteroid accumulation in the...
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Structure, function and pharmacology of NMDA receptors
Švehla, Pavel ; Vyklický, Ladislav (advisor) ; Bendová, Zdeňka (referee)
Glutamate is a major excitatory neurotransmitter between neurons in the central nervous system. The effect of glutamate is caused by the activation of distinct ionotropic glutamate channels: AMPA, kainate and NMDA receptors. NMDA receptors play a critical role in the synaptic plasticity and excitotoxicity. Despite the crucial role of these receptors in the right function of the brain, their overexcitation under pathological conditions may result in such neurological disorders as Alzheimers, Parkinsons and Huntingtons diseases. The aim of this work is to review available data concerning the molecular structure of NMDA subtype of ionotropic glutamate receptors, their pharmacology and therapeutic potential.
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Ionotropic glutamate receptors and excitotoxicity
Skřenková, Kristýna ; Vyklický, Ladislav (advisor) ; Moravec, Jan (referee)
Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system and its excitatory role is mediated trough activation of glutamatergic ionotropic receptors which are responsible for synaptic transmission and play an important role in learning and memory formation. However, excessive exposure to glutamate can result in excitotoxicity which may lead to cell death. The following text is focused on one group of glutamate receptors - NMDA receptors. The study of the receptors is in the centre of current neurobiology research because there is a series of experimental and clinical evidences that they directly participate in the development of serious diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease and may cause neuronal damage in trauma, hypoxia and embolia. The aim of this bachelor thesis is to give a brief overview of current knowledge about the structure and function of NMDA receptors and mechanisms of their activation which leads to excitotoxicity and related neuroprotection.
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