@phdthesis{Pennington2018, author = {Pennington, Laura Sophie}, title = {The role of Cadherin-13 in serotonergic neurons during different murine developmental stages}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-161331}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2018}, abstract = {Abstract Background: Attention-deficit/ hyperactivity disorder (ADHD) ranges among the most common neurodevelopmental disorders worldwide with a prevalence of 3-12\% in childhood and 1-5\% for adults. Over the last decade extensive genetic research has been conducted in order to determine its causative genetic factors. None of the so far identified susceptibility genes, however, could explain the estimated ADHD heritability of 76\%. In this thesis one of the most promising candidates -Cadherin 13 (Cdh13) - was examined in terms of its influence on the central serotonergic (5-HT) system. In addition to that, the Cdh13 protein distribution pattern was analysed over time. Methods: The developing serotonergic system was compared over three embryonic and postnatal stages (E13.5, E17.5 and P7) in different Cdh13 genotypes (WT, HZ and KO) using immunohistochemistry and various double staining protocols. Results: The raphe nuclei of the 5-HT system develop in spite of Cdh13 absence and show a comparable mature constellation. The cells in the KO, however, are slightly more scattered than in the WT. Furthermore the dynamics of their formation is altered, with a transient delay in migration at E13.5. In early developmental stages the total amount of serotonergic cells is reduced in KO and HZ, though their proportional distribution to the raphe nuclei stays constant. Strikingly, at P7 the absolute numbers are comparable again. Concerning the Cdh13 protein, it shows high concentrations on fibres running through hindbrain and midbrain areas at E13.5. This, however, changes over time, and it becomes more evenly spread until P7. Furthermore, its presence in serotonergic cells could be visualised using confocal microscopy. Since the described pattern is only in parts congruent to the localisation of serotonergic neurons, it is most likely that Cdh13 is present in other developing neurotransmitter systems, such as the dopaminergic one, as well. Conclusion: It could be proven that Cdh13 is expressed in serotonergic cells and that its knockout does affect the developing serotonergic system to some degree. Its absence, however, only slightly and transiently affects the measured parameters of serotonergic system development, indicating a possible compensation of CDH13 function by other molecules in the case of Cdh13 deficiency. In addition further indicators could be found for an influence of Cdh13 on outgrowth and path finding of neuronal processes.}, subject = {Cadherine}, language = {en} } @phdthesis{Bacmeister2018, author = {Bacmeister, Lucas}, title = {Effect of Cadherin-13 inactivation on different GABAergic interneuron populations of the mouse hippocampus}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172693}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2018}, abstract = {Cadherin-13 (CDH13) is an atypical member of the cadherin superfamily, a group of membrane proteins mediating calcium-dependent cellular adhesion. Although CDH13 shows the classical extracellular cadherin structure, the typical transmembrane and cytoplasmic domains are absent. Instead, CDH13 is attached to the cell membrane via a glycosylphosphatidylinositol (GPI) anchor. These findings and many studies from different fields suggest that CDH13 also plays a role as a cellular receptor. Interestingly, many genome-wide association studies (GWAS) have found CDH13 as a risk gene for attention-deficit/hyperactivity disorder (ADHD) and other neurodevelopmental disorders. In previous work from our research group, strong expression of Cdh13 mRNA in interneurons of the hippocampal stratum oriens (SO) was detected. Therefore, double-immunofluorescence studies were used to evaluate the degree of co-expression of CDH13 with seven markers of GABAergic interneuron subtypes. For this purpose, murine brains were double stained against CDH13 and the respective marker and the degree of colocalization in the SO of the hippocampus was assessed. Based on the result of this immunofluorescence study, quantitative differences in interneuron subtypes of the SO between Cdh13 knockout (ko), heterozygote (het) and wildtype (wt) mice were investigated in this dissertation using stereological methods. In addition, genotype- dependent differences in the expression of genes involved in GABAergic and glutamatergic neurotransmission were analyzed by quantitative real-time PCR (qRT-PCR). Primers targeting different GABA receptor subunits, vesicular GABA and glutamate transporter, GABA synthesizing enzymes and their interaction partners were used for this purpose. The results of the stereological quantification of the interneuron subtypes show no significant differences in cell number, cell density or volume of the SO between Cdh13 ko, het and wt mice. On the other hand, qRT-PCR results indicate significant differences in the expression of tropomyosin-related kinase B gene (TrkB), which encodes the receptor of brain-derived neurotrophic factor (BDNF), a regulator of GABAergic neurons. This finding supports a role for CDH13 in the regulation of BDNF signaling in the hippocampus.}, subject = {Cadherine}, language = {en} } @phdthesis{KarabegneeLee2014, author = {Karabeg, n{\´e}e Lee, Margherita Maria}, title = {Differences and Similarities in the Impact of Different Types of Stress on Hippocampal Neuroplasticity in Serotonin Transporter Deficient Mice}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-115831}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2014}, abstract = {Stress has been shown to influence neuroplasticity and is suspected to increase the risk for psychiatric disorders such as major depression and anxiety disorders. Additionally, the short variant of the human serotonin transporter (5-HTT) length polymorphism (5-HTTLPR) is suggested to increase the risk for the development of such disorders. While stress as well as serotonergic signaling are not only discussed to be involved in the development of psychiatric disorders, they are also known to influence hippocampal adult neurogenesis (aN). Therefore, it has long been suspected that aN is involved in the etiology of these illnesses. The exact role of aN in this context however, still remains to be clarified. In the present doctoral thesis, I am introducing two different studies, which had been carried out to assess possible changes in neuroplasticity and behavior as a result of 5-HTT genotype by stress interactions. In both studies, animals of the 5-HTT knock-out (5-HTT-/-) mouse line were used, which have been found to exhibit increased anxiety- and depression-related behavior, an altered stress response and decreased aggressive behavior. The aim of the first study, the so-called Spatial Learning study, had been to evaluate whether mice with altered levels of brain 5-HT as a consequence of lifelong 5-HTT deficiency perform differently in two spatial memory tests, the Morris Water Maze (WM) and the Barnes Maze (BM) test prospectively differing in aversiveness. Mice of the Spatial Learning study were of male sex and six months of age, and where subjected to a total of 10 (BM) or 15 (WM) trials. My particular interest was to elucidate if there are genotype by treatment interactions regarding blood plasma corticosterone levels and, if neurobiological equivalents in the brain to the found behavioral differences exist. For this purpose I carried out a quantitative immunohistochemistry study, investigating stem cell proliferation (via the marker Ki67) and aN (via the immature neuron marker NeuroD), as well as expression of the two immediate early genes (IEGs) Arc and cFos as a markers for neuronal activity in the hippocampus. The aim of the second study, the chronic mild stress (CMS) study had been to evaluate whether the innate divergent depression-like and anxiety-like behavior of mice with altered levels of brain 5-HT as a consequence of 5-HTT-deficiency is altered any further after being subjected to a CMS paradigm. Two cohorts of one-year-old female mice had been subjected to a variety of unpredictable stressors. In order to exclude possible interfering influences of behavioral testing on corticosterone levels and the outcome of the quantitative immunohistochemistry study the first cohort had been behaviorally tested after CMS while the second one had remained behaviorally untested. The objective of my part of the study was to find out about possible genotype by treatment interactions regarding blood plasma corticosterone as well as regarding aN in the hippocampus of the mice that had been subjected to CMS. For this purpose I performed a quantitative immunohistochemistry study in order to investigate the phenomenon of adult neurogenesis (via Ki67, NeuroD and the immature neuron marker DCX). Both studies led to interesting results. In the CMS study, we could not replicate the increased innate anxiety- and depression-like behavior in 5-HTT-/- mice known from the literature. However, with regard to the also well documented reduced locomotor activity, as well as the increased body weight of 5-HTT-/- mice compared to their 5-HTT+/- and 5-HTT+/+ littermates, we could demonstrate that CMS leads to increased explorative behavior in the Open Field Test and the Light/Dark Box primarily in 5-HTT+/- und 5-HTT+/+ mice. The Spatial learning study revealed that increased stress sensitivity of 5-HTT-/- mice leads to a poorer performance in the WM test in relation to their 5-HTT+/+ and 5-HTT+/- littermates. As the performance of 5-HTT-/- mice in the less aversive BM was undistinguishable from both other genotypes, we concluded that the spatial learning ability of 5-HTT-/- mice is comparable to that of both other genotypes. As far as stress reactivity is concerned, the experience of a single trial of either the WM or the BM resulted in increased plasma corticosterone levels, irrespective of the 5-HTT genotype. After several trials 5-HTT-/- mice exhibited higher corticosterone concentrations compared with both other genotypes in both tests. Blood plasma corticosterone levels were highest in 5-HTT-/- mice tested in the WM indicating greater aversiveness of the WM and a greater stress sensitivity of 5-HTT deficient mice. In the CMS study, the corticosterone assessment of mice of cohort 1, which had undergone behavioral testing before sacrifice, resulted in significantly elevated corticosterone levels in 5-HTT-/- mice in relation to their 5-HTT+/+ controls. Contrary, corticosterone levels in mice of cohort 1, which had remained behaviorally untested, were shown to be elevated / increased after CMS experience regardless of the 5-HTT genotype. Regarding neuroplasticity, the Spatial Learning study revealed higher baseline levels of cFos- and Arc-ir cells as well as more proliferation (Ki67-ir cells) and higher numbers of neuronal progenitor cells (NeuroD-ir cells) in 5-HTT-/- compared to 5-HTT+/+ mice. Moreover, in 5-HTT-/- mice we could demonstrate that learning performance in the WM correlates with the extent of aN. The CMS study, in which aN (DCX-ir cells), has also been found to be increased in 5-HTT-/- mice compared to their 5-HTT+/+ littermates, yet only in control animals, did show hampered proliferation (Ki67-ir cells) in the hippocampus of all 5-HTT genotypes following CMS experience. Interestingly, the number of immature neurons (DCX-ir cells) was diminished exclusively in 5-HTT-/- mice in response to CMS. From the Spatial Learning study we concluded, that increased IEG expression and aN levels observed in the hippocampus of 5-HTT deficient mice can be the neurobiological correlate of emotion circuit dysfunction and heightened anxiety of these mice and that 5-HTT-/- animals per se display a "stressed" phenotype as a consequence of long-life 5-HTT deficiency. Due to the different age and sex of the mice in the two studies, they cannot be compared easily. However, although the results of the CMS study seem to contradict the results of the Spatial Learning study at the first glance, they do support the conclusion of the Spatial Learning study by demonstrating that although CMS does have an impact on 5-HTT-/- mice on the neurobiological level (e.g. manifesting in a decrease of DXC-ir cells following CMS) CMS experience cannot add onto their heightened inborn stress-level and is almost ineffective regarding further changes of the behavior of 5-HTT-deficient mice. I thus propose, that 5-HTT-/- mice as a result of lifelong altered 5-HT signaling display a stressed phenotype which resembles a state of lethargy and is paralleled by baseline heightened IEG expression and aN. It cannot be altered or increased by CMS, but it becomes most visible in stressful situations such as repeated spatial learning tests like the WM in which locomotor activity is required.}, subject = {Serotonin}, language = {en} } @phdthesis{Kreutzfeldt2013, author = {Kreutzfeldt, Simon}, title = {Studien zur Expression von Megalencephalic leukoencephalopathy with subcortical cysts 1 (MLC1/Mlc1) in humanen und murinen Geweben}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-90355}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2013}, abstract = {Das humane MLC1 (auch als KIAA0027 oder WKL1 benannt) ist ein 377 AS umfassendes Protein, welches vornehmlich in neuralen Geweben exprimiert wird. Aufgrund von Strukturanalysen und Homologievergleichen wurde eine Funktion als Ionenkanal mit acht Transmembrandom{\"a}nen postuliert. Loss-of-function-Mutationen des MLC1-Gens lassen sich mit dem Auftreten der Megalenzephale Leukenzephalopathie mit subkortikalen Zysten korrelieren. Ferner konnte anhand einer Stammbaumanalyse gezeigt werden, dass die C1121A-Mutation in einer gr{\"o}ßeren Familie mit dem Auftreten der Periodischen Katatonie nach Leonhardt (PK) kosegregierte, wobei Folgeuntersuchungen zur Assoziation von MLC1-Mutationen und dem Auftreten der PK widerspr{\"u}chliche Ergebnisse erbrachten. Zur weiteren Aufkl{\"a}rung der biologischen Funktion von MLC1 war es das Ziel der vorliegenden Arbeit, in zwei experimentellen Ans{\"a}tzen n{\"a}here Kenntnisse zum transkriptionellen Expressionsmuster von MLC1 in vivo zu gewinnen, und anschließend durch Herstellung eines polyklonalen Antik{\"o}rpers gegen das humane MLC1 den Grundstein f{\"u}r weitergehende Untersuchungen zur funktionellen Bedeutung von MLC1 zu legen. Mittels In Situ-Hybridisierung humaner und muriner Gewebeschnitte aus Hippocampus und Cerebellum konnte gezeigt werden, dass die MLC1/Mlc1-Transkription in diesen Geweben vornehmlich in den Bergmann-Gliazellen der Purkinjezellschicht des Cerebellums sowie - in schw{\"a}cherem Umfang - in verstreut liegenden und in der subgranul{\"a}ren Zone des Gyrus dentatus geh{\"a}uften Astrozyten des murinen Hippocampus nachweisbar war. Im zweiten Schritt der Analyse wurden humane post-mortem cDNA-Proben aus verschiedenen Gehirnregionen und zus{\"a}tzlich einigen nicht-neuralen Geweben von zwei Menschen gewonnen, mittels quantitativer Real-time-PCR die Genexpression von MLC1 bestimmt und mithilfe des Expressionsniveaus von ausgew{\"a}hlten Housekeeping-Genen (GAPDH, L13a, β-Aktin, ARP und Cyclophilin) normalisiert. Es zeigte sich, dass in allen getesteten Hirnregionen eine deutliche MLC1-Expression festzustellen war, deren Maxima im Cerebellum und Frontalhirn und deren Minima im Putamen bzw. im nicht-neuralen Plexus chorioideus lagen. Zudem konnte eine nicht-neurale Expression auf sehr geringem Niveau f{\"u}r Lunge und Milz nachgewiesen werden. Zur Gewinnung eines polyklonalen Antik{\"o}rpers gegen humanes MLC1 wurden mittels computergest{\"u}tzter Verfahren ein 117 AS langes Vakzinierungsprotein entworfen, welches immunogene Abschnitte des N-Terminus (61 AS) und C-Terminus (54 AS) enthielt. Die kodierende Sequenz wurde unter Verwendung des Impact-CN®-Expressionssystems in einen pTYB-Vektor kloniert, in ER2566-Zellen exprimiert, das Protein affinit{\"a}tschromatographisch {\"u}ber Chitin-S{\"a}ulen isoliert und aufgereinigt und mittels Bradford-Assay und SDS-Gelelektrophorese nachgewiesen. Leider konnte trotz vielf{\"a}ltiger Variation der Versuchsparameter kein eindeutiger Nachweis einer ausreichenden Expression des MLC1-Proteins in den ER2566-Zellen erbracht werden, die f{\"u}r die anschließende Vakzinierung von Kaninchen zur Gewinnung des polyklonalen Antiserums erforderlich gewesen w{\"a}re. Die Gr{\"u}nde hierf{\"u}r sind unklar, denkbar sind beispielsweise eine suboptimale Codon-Frequenz, eine schlechte Proteinl{\"o}slichkeit, intrazellul{\"a}re mRNA-Degradation, proteolytische Abbauvorg{\"a}nge oder eine Hemmung der Proteinbiosynthese durch die biologische Funktion des Proteins. Zusammenfassend konnten die im Rahmen dieser Arbeit erzielten Ergebnisse einen Beitrag zur Erweiterung des Wissens zur MLC1-Expression leisten. Dabei entsprachen die Befunde zur humanen MLC1-Expression weitgehend den diesbez{\"u}glichen Beobachtungen zur regionalen und zellul{\"a}ren Expressionsst{\"a}rkenverteilung aus dem Mausmodell, welche eine funktionelle Bedeutung von MLC1 im Rahmen von neuralen Schrankenstrukturen nahelegten (vgl. Schmitt et al. 2003). Mittels der zwischenzeitlich von anderen Arbeitsgruppen ({\"u}ber andere experimentelle Verfahren) erzeugten Antik{\"o}rper gegen MLC1 konnte gezeigt werden, dass funktionelles MLC1 vermutlich als zellmembranst{\"a}ndiges Dimer vorliegt und seine biologische Funktion u.a. durch Interaktion mit dem DGC (=Dystrophin-assoziierten Glykoprotein-Komplex) in den Caveolae aus{\"u}bt. Es bleibt eine Aufgabe f{\"u}r die Zukunft, die genauen molekularen Mechanismen dieser Prozesse und ihre m{\"o}gliche therapeutische Beeinflussbarkeit zur Behandlung der MLC zu erforschen. Auch die Frage der potenziellen extraneuralen MLC1-Expression, f{\"u}r die in dieser Arbeit Hinweise gefunden wurden, mag ein interessanter Ansatzpunkt f{\"u}r zuk{\"u}nftige Forschungsarbeiten sein.}, subject = {MLC1}, language = {de} } @phdthesis{Auth2021, author = {Auth, Charlotte Sophie}, title = {Die Auswirkungen von Tph2-Defizienz und negativen fr{\"u}hen Umwelterfahrungen auf Angstverhalten in weiblichen M{\"a}usen}, doi = {10.25972/OPUS-23948}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239488}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {Angsterkrankungen geh{\"o}ren zu den am weitesten verbreiteten psychischen Erkrankungen und stellen eine betr{\"a}chtliche soziale und wirtschaftliche Herausforderung f{\"u}r unsere Gesellschaft dar. Aversive fr{\"u}he Erfahrungen sind ein bekannter Risikofaktor f{\"u}r die Entwicklung verschiedener psychischer Erkrankungen, insbesondere Angstst{\"o}rungen. W{\"a}hrend der fr{\"u}hen Entwicklung findet die Programmierung der Hypothalamus-Hypophysen-Nebennierenrinden- (HHN)-Achse, die die Aussch{\"u}ttung des Stresshormons Cortisol in Menschen bzw. Corticosteron in M{\"a}usen steuert, statt. Wenn Individuen in dieser kritischen Phase Stress ausgesetzt sind, wird die regelrechte Ausbildung der HHN-Achse gest{\"o}rt, was zu dysregulierten Verhaltensantworten auf Stressreize im sp{\"a}teren Leben f{\"u}hren kann. Das Serotonin (5-HT)-System als eines der ausgedehntesten Neurotransmittersysteme ist an der Vermittlung der Effekte von fr{\"u}her Stressexposition auf angst{\"a}hnliche Verhaltensweisen beteiligt. Das Ziel dieser Studie ist es, die Interaktion zwischen genetischer Pr{\"a}disposition und negativen Einfl{\"u}ssen in fr{\"u}hen Entwicklungsstadien auf die Ausbildung von Angstverhalten im Erwachsenenalter n{\"a}her zu beleuchten. In dieser Studie wurden Tryptophanhydroxylase 2 (Tph2)-defiziente weibliche M{\"a}use als Modell f{\"u}r ein lebenslanges konstitutives 5-HT Synthesedefizit im zentralen Nervensystem verwendet. Nachkommen dieser Mauslinie wurden im fr{\"u}hen Lebensalter Maternaler Separation (MS), d.h. einem m{\"u}tterlichen Trennungsparadigma, unterzogen und im Erwachsenenalter im „Open field" (OF) oder in der „Dark-light box" (DLB) getestet. Im Anschluss an die Verhaltensexperimente wurde die neuronale Aktivierung immunhistochemisch durch Darstellung des fr{\"u}hzeitig auftretenden Genprodukts c-Fos bestimmt. In der DLB zeigten homozygot Tph2-defiziente M{\"a}use eine verringerte motorische Aktivit{\"a}t im hellen Kompartiment, und dieser Effekt konnte durch MS normalisiert werden. Zus{\"a}tzlich verst{\"a}rkte MS bei diesem Genotyp das Auftreten von fluchtartigen Spr{\"u}ngen. Im OF hat MS fluchtartige Verhaltensweisen in homo- und heterozygoten Tph2-defizienten M{\"a}usen bef{\"o}rdert. Beide Verhaltenstests f{\"u}hrten zu spezifischen neuronalen Aktivierungsmustern, die mithilfe von c-Fos- Immunhistochemie ausgewertet wurden. Die Durchf{\"u}hrung des DLB-Tests f{\"u}hrte in Abh{\"a}ngigkeit vom Vorhandensein von Tph2 zur Aktivierung des paraventrikul{\"a}ren Kerns des Hypothalamus (PVN) und der basolateralen Amygdala (BL), wohingegen die Exposition gegen{\"u}ber dem OF-Test zu einer Aktivierung der lateralen Amygdala (La) in Tieren, die einem m{\"u}tterlichen Trennungsparadigma unterzogen wurden, sowie einer Aktivierung des ventrolateralen (VLPAG) und dorsolateralen (DLPAG) periaqu{\"a}duktalen H{\"o}hlengraus in Abh{\"a}ngigkeit von Tph2 und MS f{\"u}hrte. Zusammenfassend weisen die Ergebnisse dieser Studie darauf hin, dass MS aktive Verhaltensantworten auf aversive Reize in Abh{\"a}ngigkeit vom Vorhandensein von 5-HT im Gehirn f{\"o}rdert. Diese Effekte k{\"o}nnten durch die spezifische Aktivierung von mit Angstverhalten in Zusammenhang stehenden Gehirnregionen w{\"a}hrend der Verhaltensexperimente vermittelt werden.}, subject = {Angst}, language = {de} }