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Lai, Kuei-Hung
(författare)
Studies on anti-leukemic terpenoids from medicinal mushrooms and marine sponges with ChemGPS-NP-based targets investigation of lead compounds
2017
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
This thesis investigates the anti-leukemic activity of terpenoids isolated from medicinal mushrooms and marine sponges, as well as their possible targets and mechanisms of action.In the first section, we focused on studying the triterpenoidal components of three triterpenoid-enriched medicinal mushrooms Antrodia cinnamomea, Ganoderma lucidum, and Poria cocos, which have been used in folk medicine for centuries and also developed into several contemporary marketed products. We isolated the major and characteristic triterpenoids from these mushrooms, together with six new lanostanoids (II-1–II-6). The anti-leukemic activity of the isolates was evaluated in vitro using MTT proliferative assay and seven of them exhibited potential anti-leukemic effect. The active lead compounds were further subjected to computational analyses utilizing the ChemGPS-NP tool. We established a database for the anti-leukemic relevant chemical space of triterpenoids isolated from these three medicinal mushrooms, which could be used as a reference database for further research on anti-leukemic triterpenoids. Our results indicated that the anti-leukemic effect of the active lead compounds was mediated not only through topoisomerases inhibition but also through inhibiting DNA polymerases.The second and third sections focused on isolation of anti-leukemic sesterterpenoids from sponges. The investigation of Carteriospongia sp. led to the isolation of two new scalarane-type sesterterpenoids (III-1 and III-2) and one known tetraprenyltoluquinol-related metabolite (III-3). All isolates exhibit an apoptotic mechanism of action against Molt 4 cells, found to be mediated through the disruption of the mitochondrial membrane potential (MMP) and inhibition of topoisomerase IIα expression. Detailed investigation of the apoptotic mechanism of action using molecular docking analysis revealed that compound III-1 might target Hsp90 protein. The apoptotic-inducing effect of III-3 was supported by in vivo experiment by suppressing the volume of xenograft tumor growth (47.58%) compared with the control.In the final section of this thesis we studied manoalide and its derivatives, sesterterpenoids isolated from the sponge Luffariella sp.. Manoalide has been studied as a potential anti-inflammatory agent for the last thirty years with more than 200 publications and 40 patents. However, the configurations at positions 24 and 25 were never revealed. In the current study, ten manoalide-type sesterterpenoids (IV-1–IV-10) were isolated from Luffariella sp. and their stereoisomers at positions 24 and 25 were identified and separated for the first time. The configuration at positions 24 and 25 showed to have a significant effect on the anti-leukemic activity of manoalide derivatives, with the 24R,25S-isomer exhibiting the most potent anti-leukemic activity. The apoptotic mechanism of action of compound IV-7 against Molt 4 cells was investigated, and the compound was found to trigger MMP disruption and intracellular reactive oxygen species (ROS) generation. Compound IV-7 also inhibited activity against both human topoisomerases, I and II. The in vivo experiment further supported the anti-leukemic effect of IV-7 with a 66.11% tumor volume suppression compared to the control.
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Klawonn, Anna, 1985-
(författare)
Molecular Mechanisms of Reward and Aversion
2017
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Various molecular pathways in the brain shape our understanding of good and bad, as well as our motivation to seek and avoid such stimuli. This work evolves around how systemic inflammation causes aversion; and why general unpleasant states such as sickness, stress, pain and nausea are encoded by our brain as undesirable; and contrary to these questions, how drugs of abuse can subjugate the motivational neurocircuitry of the brain. A common feature of these various disease states is involvement of the motivational neurocircuitry - from mesolimbic to striatonigral pathways. Having an intact motivational system is what helps us evade negative outcomes and approach natural positive reinforcers, which is essential for our survival. During disease-states the motivational neurocircuitry may be overthrown by the molecular mechanisms that originally were meant to aid us.In study I, to investigate how inflammation is perceived as aversive, we used a behavioral test based on Pavlovian place conditioning with the aversive inflammatory stimulus E. coli lipopolysaccharide (LPS). Using a combination of cell-type specific gene deletions, pharmacology, and chemogenetics, we uncovered that systemic inflammation triggered aversion by MyD88-dependent activation of the brain endothelium followed by COX1-mediated cerebral prostaglandin E2 (PGE2) synthesis. Moreover, we showed that inflammation-induced PGE2 targeted EP1 receptors on striatal dopamine D1 receptor–expressing neurons and that this signaling sequence induced aversion through GABA-mediated inhibition of dopaminergic cells. Finally, inflammation-induced aversion was not an indirect consequence of fever or anorexia but constituted an independent inflammatory symptom triggered by a unique molecular mechanism. Collectively, these findings demonstrate that PGE2-mediated modulation of the dopaminergic circuitry is a key mechanism underlying inflammation-induced aversion.In study II, we investigate the role of peripheral IFN-γ in LPS induced conditioned place aversion by employing a strategy based on global and cell-type specific gene deletions, combined with measures of gene-expression. LPS induced IFN-ɣ expression in the blood, and deletion of IFN-ɣ or its receptor prevented conditioned place aversion (CPA) to LPS. LPS increased the expression of chemokine Cxcl10 in the striatum of normal mice. This induction was absent in mice lacking IFN-ɣ receptors or Myd88 in blood brain barrier endothelial cells. Furthermore, inflammation-induced aversion was blocked in mice lacking Cxcl10 or its receptor Cxcr3. Finally, mice with a selective deletion of the IFN-ɣ receptor in brain endothelial cells did not develop inflammation-induced aversion. Collectively, these findings demonstrate that circulating IFN-ɣ binding to receptors on brain endothelial cells which induces Cxcl10, is a central link in the signaling chain eliciting inflammation-induced aversion.In study III, we explored the role of melanocortin 4 receptors (MC4Rs) in aversive processing using genetically modified mice in CPA to various stimuli. In normal mice, robust aversions were induced by systemic inflammation, nausea, pain and kappa opioid receptor-induced dysphoria. In sharp contrast, mice lacking MC4Rs displayed preference towards most of the aversive stimuli, but were indifferent to pain. The unusual flip from aversion to reward in mice lacking MC4Rs was dopamine-dependent and associated with a change from decreased to increased activity of the dopamine system. The responses to aversive stimuli were normalized when MC4Rs were re-expressed on dopamine D1 receptor-expressing cells or in the striatum of mice otherwise lacking MC4Rs. Furthermore, activation of arcuate nucleus proopiomelanocortin neurons projecting to the ventral striatum increased the activity of striatal neurons in a MC4R-dependent manner and elicited aversion. Our findings demonstrate that melanocortin signaling through striatal MC4Rs is critical for assigning negative motivational valence to harmful stimuli.The neurotransmitter acetylcholine has been implied in reward learning and drug addiction. However, the role of cholinergic receptor subtypes in such processes remains elusive. In study IV we investigated the function of muscarinic M4Rs on dopamine D1R expressing neurons and acetylcholinergic neurons, using transgenic mice in various reward-enforced behaviors and in a “waiting”-impulsivity test. Mice lacking M4-receptors from D1-receptor expressing neurons exhibited an escalated reward seeking phenotype towards cocaine and natural reward, in Pavlovian conditioning and an operant self-administration task, respectively. In addition, the M4-D1RCre mice showed impaired waiting impulsivity in the 5-choice-serial-reaction-time-task. On the contrary, mice without M4Rs in acetylcholinergic neurons were unable to learn positive reinforcement to natural reward and cocaine, in an operant runway paradigm and in Pavlovian conditioning. Immediate early gene expression mirrored the behavioral findings arising from M4R-D1R knockout, as cocaine induced cFos and FosB was significantly increased in the forebrain of M4-D1RCre mice, whereas it remained normal in the M4R-ChatCre mice. Our study illustrates that muscarinic M4Rs on specific neural populations, either cholinergic or D1R-expressing, are pivotal for learning processes related to both natural reward and drugs of abuse, with opposing functionality.
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Adermark, Louise, 1974
(författare)
Astrocyte Function in Alcohol Reward and Addiction
2015
Ingår i: Journal of Alcoholism & Drug Dependence. - : OMICS Publishing Group. - 2329-6488. ; 3
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt) abstract
Glial cells, particularly astrocytes, play essential roles in the regulation of neurotransmission, metabolism, and supply of energy substrates for synaptic transmission. One astrocyte can receive inputs from several hundreds of synapses, and synchronized neuronal activity correlates with astrocyte calcium signaling. Astrocyte pathology is a common feature of ethanol exposure in both humans and animal models, and brief alcohol intake is sufficient to cause long-lasting changes in astrocyte gene expression, activity and proliferation. Recent research also suggests that astrocytes shape the rewarding sensation of ethanol, and might be involved in modulating alcohol consumption. Considering the role of astrocytes in regulating glutamate homeostasis, a crucial component of alcohol abuse disorders, the astrocyte might be an important target for the development of new pharmacological treatments of alcoholism.
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Boknäs, Niklas, 1979-
(författare)
Studies on interfaces between primary and secondary hemostasis
2016
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Our conceptual understanding of hemostasis is still heavily influenced by outdated experimental models wherein the hemostatic activity of platelets and coagulation factors are understood and studied in isolation. Although perhaps convenient for researchers and clinicians, this reductionist view is negated by an ever increasing body of evidence pointing towards an intimate relationship between the two phases of hemostasis, marked by strong interdependence. In this thesis, I have focused on factual and proposed interfaces between primary and secondary hemostasis, and on how these interfaces can be studied.In my first project, we zoomed in on the mechanisms behind the well-known phenomenon of thrombin-induced platelet activation, an important event linking secondary to primary hemostasis. In our study, we examined how thrombin makes use of certain domains for high-affinity binding to substrates, called exosite I and II, to activate platelets via PAR4. We show that thrombin-induced platelet activation via PAR4 is critically dependent on exosite II, and that blockage of exosite II with different substances virtually eliminates PAR4 activation. Apart from providing new insights into the mechanisms by which thrombin activates PAR4, these results expand our knowledge of the antithrombotic actions of various endogenous proteins such as members of the serpin superfamily, which inhibit interactions with exosite II. Additionally, we show that inhibition of exosite II could be a feasible pharmacological strategy for achieving selective blockade of PAR4.In my second project, we examined the controversial issue of whether platelets can initiate the coagulation cascade by means of contact activation, a hypothesis which, if true, could provide a direct link between primary and secondary hemostasis. In contrast to previous results, our findings falsify this hypothesis, and show that some of the erroneous conclusions drawn from earlier studies can be explained by inappropriate experimental models unsuitable for the study of plateletcoagulation interfaces.My third project comprised an assessment of the methodological difficulties encountered when trying to measure the ability of platelets to initiate secondary hemostasis by the release of microparticles expressing tissue factor. Our study shows that the functional assays available for this purpose are highly susceptible to error caused by artificial contact activation. These results could help to improve the methodology of future research and thus pave the way for new insights into the roles of tissue factor-bearing microparticles in the pathophysiology of various thrombotic disorders.From a personal perspective, my PhD project has been a fascinating scientific odyssey into the largely unexplored interfaces between primary and secondary hemostasis. Looking forward, my ambition is to continue our work exploring platelet-coagulation interactions and to translate these insights into clinically meaningful information, which may someday improve the treatment of patients with bleeding and/or thrombosis.
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Skovgård, Katrine
(författare)
Models and biomarkers of motor and neuropsychiatric complications in Parkinson’s disease
2023
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Parkinson's disease (PD) is a neurodegenerative disorder characterised by typicalmotor symptoms that are caused by severe dopamine depletion in the cortico-basalganglia network. Parkinsonian motor symptoms are improved by dopaminergicmedications, the most effective being the dopamine precursor L-DOPA. Thiscompound exerts its motor effects by stimulating dopamine D1 and D2 receptors,whose expression are segregated between the movement-promoting and movement-suppressing pathways of the basal ganglia circuitry. As the disease progresses,treatment with L-DOPA give rise to involuntary movements (dyskinesia), whichlimits its utility. Drugs that directly stimulate dopamine receptors, referred to asdopamine agonists, are commonly used to delay the use of L-DOPA or reduce itsdosage. Although less prone to induce dyskinesia, dopamine agonists have a highliability to induce neuropsychiatric side effects, in particular, impulsive-compulsivebehaviours. However, it remains to be established whether pharmacotherapiescombining L-DOPA and dopamine agonists give rise to specific profiles of motorand non-motor complications.The overarching aim of this thesis is to develop improved experimental modelsto advance translational research on the motor and neuropsychiatric complicationsof PD therapy. Both well-established and new experimental models are used todefine correlations and causal links between regimens of dopaminergic treatment,behavioural changes, and biomarkers of network and cellular dysfunction in thecortico-basal ganglia system.Using in vivo local field potential recordings to study biomarkers of networkdysfunctions, we show that changes in broad-band oscillatory activities of cortico-striatal circuits are correlated to ongoing motions and do not reflect parkinsonian-specific states. Moreover, we demonstrate that dyskinesias induced by D1 receptorstimulation are associated with prominent narrowband cortico-striatal oscillationsin the high gamma range (70-110 Hz). Following treatment with a D2 agonist, thesenarrowband gamma oscillations are less pronounced, whereas this treatment inducesprominent theta oscillations (5-10 Hz) in the deep basal ganglia nuclei. Thus, thecomposition of the dopaminergic therapies might affect these neurophysiologicalbiomarkers and should be considered in future investigations.Next, using a set of pharmacological tools and markers of cellular dysfunctions,we show that adjuvant treatment with D2/3 agonists alters the pattern of dopamine-related neuroplasticity in the basal ganglia compared to L-DOPA monotherapy,despite similar dyskinetic behaviours. The antidyskinetic effects of compounds modulating D1 receptor signalling were stronger in L-DOPA-treated animals, whileNMDA receptor antagonists produced markedly larger effects in the combinedtreatment group. Thus, adjuvant dopamine agonist treatment has a significantimpact on the neuroplasticity and pharmacological response profiles of L-DOPA-induced dyskinesia. In a last study, we show that treatment with a D2/3 agonistinduces compulsive behaviours and impulsive decision-making in both intact andpartially dopamine-depleted rats regardless of L-DOPA coadministration.Taken together, the findings of this thesis shed new light on the maladaptivecellular changes and network dynamics through which dopaminergic pharmacotherapies for PD affects motor behaviours. Moreover, this thesis work reveals the importance of including realistic models of combined therapies in future translational research on L-DOPA-induced dyskinesia.
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Stafberg, Linda, et al.
(författare)
The mRNA expression of endocannabinoid-related enzymes in rat prostate AT-1 cells following exposure to lactate and interleukin-6
Annan publikation (övrigt vetenskapligt/konstnärligt) abstract
The endocannabinoid system is dysregulated in prostate cancer but the mechanisms responsible for this dysregulation are not known. We hypothesise that the dysregulation is secondary to factors in the tumour microenvironment. In this study we investigated the effects of lactic acid induced low pH and interleukin-6 (IL-6) treatment upon the expression of endocannabinoid related enzymes and the functional effects upon anandamide degradation and cell viability in Dunning R3327 rat prostate AT-1 cancer cells. Cells were exposed for 3 h at 37 °C to Krebs-Ringer-HEPES/bicarbonate buffer at either pH 7.4 or at pH 6.6 (due to the presence of 40 mM lactic acid), and to 0, 25 or 100 ng/ml of IL-6. Neither low pH (pH 6.6) nor IL-6 induced any changes in the mRNA levels of the anandamide metabolic enzymes. However, the expression of the 2- arachidonoylglycerol-synthesizing enzyme DAGLα was increased by low pH and the expression of CB2 receptor mRNA was decreased at the low pH. The DAGL inhibitor orlistat increased extracellular LDH levels after 24 h of incubation of AT-1 cells, suggesting a higher frequency of cell death. It is concluded that under the conditions used, exposure to lactate and IL-6 do not affect the expression of the anandamide metabolic enzymes in AT-1 cells, but do modify the expression of an enzyme involved in the synthesis of 2-arachidonoylglycerol.
