effects of serotonergic lesions on the striatal high affinity dopamine uptake in rats

Titelblatt, Inhaltsverzeichnis, Lebenslauf 1\. Einleitung 2.1 Literatur Teil 1 2.2 Literatur Teil 2 2.3 Literatur Teil 3 3\. Zielstellung der Arbeit 4\. Material und Methoden 5\. Versuchsauswerung und Statistik 6\. Ergebnisse 7\. Diskussion 8\. Zusammenfassung 9\. Summary LiteraturverzeichnisInteraktive Regulationsmuster verschiedener Transmissionssysteme sind grundlegende Mechanismen physiologischer Hirnfunktion. Nicht die Betrachtung von Transmissionssystemen in ihrer Singularität, sondern der Untersuchungsansatz, die Funktionsweise des ZNS als interagierendes System zu verstehen, verspricht eine Weiterentwicklung in der Erkenntnis physiologischer sowie pathophysiologischer Zusammenhänge. Bisherige Daten über wechselseitige Beziehungen zwischen dopaminergem und serotonergem Transmissionssystem verweisen auf eine Komplexität, die mit ihrem klinischem Hintergrund ein Potential der gegenseitigen Kompensation zentraler Funktionsdefizite erwarten lässt. Mit dem Ziel, diese Interaktion auf Ebene der dopaminergen Transmissionsregulation im STR genauer zu charakterisieren, ist in vorliegender Arbeit mit Hilfe in vivo voltammetrischer Methodik die Funktion des striatalen DAT in Folge einer 5-HT-Läsion untersucht worden. Aufgabenstellung war, den DAT-vermittelten hochaffinen striatalen DA-Uptake nach Läsion der kranialen Raphekerne (DRN bzw. MRN) zu ermitteln und einen möglichen läsionsbedingten Effekt in seiner zeitlichen Ausprägung sowie Altersabhängigkeit darzustellen. Die Untersuchungen wurden an Ratten vom Stamm Sprague Dawley vorgenommen. Tiere zweier Altersklassen (7 Wochen bzw. 10 Monate) erhielten durch Applikation des Neurotoxins 5,7-DHT in jeweils einen der kranialen Raphekerne, DRN oder MRN, eine direkte Läsion der Ursprungsgebiete der zentralen serotonergen Projektion. Nach einem Zeitraum von einer, drei oder neun Wochen folgte unter Anwendung des voltammetrischen Verfahrens der CA und nach elektrisch stimulierter Transmitterfreisetzung (Stimulation des MFB) die Bestimmung der striatalen DA-Clearancerate. Es wurden Messreihen jeweils vor und nach Blockade der DAT durch den DAT- Inhibitor GBR 12909 vorgenommen. Im Anschluss an die voltammetrische Untersuchung wurden die Gehirne perfusionsfixiert und der Läsionserfolg 5-HT- immunhistochemisch überprüft. Die Auswertung des amperometrischen Messsignals mit Berechnung der Geschwindigkeitskonstanten k [1/s] des hochaffinen striatalen DA-Uptakes erfolgte auf Grundlage eines kinetischen Modells. Die Ergebnisse vorliegender Studie verdeutlichen eine Abhängigkeit des striatalen DAT von der serotonergen Funktion. Sowohl bei den jungen, als auch den adulten Tieren zeigte sich im Vergleich zu Scheinläsionen und unbehandelten Kontrollen eine Verlangsamung des striatalen hochaffinen DA-Uptakes eine Woche nach 5-HT- Läsion. Bei den Jungtieren, nicht aber bei den Adulten, war dieser Effekt auch drei Wochen nach Läsionswirkung feststellbar, nach neun Wochen konnte diese DAT-Funktionsänderung bei beiden Altersklassen nicht mehr beobachtet werden. Die Daten vor und nach Gabe von GBR 12909 verweisen zusätzlich auf weitere regulative Mechanismen, die mit serotonerger Läsion bzw. einer herabgesetzten DAT-Funktion auftreten. Es hat sich mit den Ergebnissen dieser Studie bestätigt, dass das serotonerge und dopaminerge System in enger Wechselwirkung bzw. einem Abhängigkeitsverhältnis zueinander stehen. Die herausragende Rolle des dopaminergen Systems für striatale- und insgesamt BG-Funktionen hebt die Bedeutung von Erkenntnissen hervor, die mit dem Verständnis regulativer Steuergrößen einhergehen. Die Abhängigkeit des gezeigten Effektes vom Tieralter unterstützt Studien zu Alterungsprozessen des ZNS, welche veränderte anatomische, biochemische und elektrophysiologische Bedingungen beschreiben. Es liegt daher nahe, dass auftretenden Funktionsstörungen altersabhängig unterschiedliche Regulationsmuster entgegenwirken. Obwohl die Daten dieser Studie eine umfassende Interpretation des gezeigten Effektes nicht ermöglichen, kann mit Hintergrund der bisherigen Erkenntnisse zu Interaktionen beider aminerger Transmittersysteme vermutet werden, dass es sich bei den Veränderungen der DAT-Funktion um eine kompensatorische Leistung des ZNS handeln könnte, das serotonerge Defizit auszugleichen.The fundamental physiological functions of the brain can be described by interactive regulation models of various transmission systems. A better understanding of physiological and pathophysiological connections can be achieved, if, rather than describing transmissions systems singly, the functions of the central nervous system are seen as an interactive network. Previous research on cross-relations between the dopamine and serotonin transmission systems suggest a complexity, with reciprocal compensation of functional deficits. The objective of this study was to investigate the interaction of both transmission systems by characterising regulative mechanisms of dopaminergic transmission in the striatum. In vivo voltammetry was used to examine the function of the striatal dopamine transporter (DAT) after 5,7-dihydroxytryptamine-lesion of the cranial raphe nuclei of Sprague Dawley rats. The aim was to describe the DAT-mediated high affinity dopamine uptake after lesions to the dorsal or median raphe nucleus and also to detect any lesion-related time-dependent or age-dependent effects. Seven and ten weeks old animals were lesioned with the neurotoxin 5,7-DHT injected in one of the cranial raphe nuclei to ensure direct lesion of the original areas of serotonergic projection. The electrically evoked striatal dopamine clearance was measured one, three or nine weeks after lesion using continuous amperometry. Measurements were conducted before and after the DAT was blocked by the DAT-inhibitor GBR 12909. Following the voltammetric investigations brains were preserved by perfusion, and successful lesions were confirmed by 5-HT immunohistochemistry. A kinetic model was used to calculate the rateconstante k [1/s] of high affinity dopamine uptake from the measured amperometric signals. The results of this study demonstrate the dependence of the striatal DAT on the serotonin function. A slow down of the striatal high affinity dopamine uptake one week after 5-HT lesion was observed in both, young and old animals, when compared to sham-lesioned rats and untreated controls. Young animals, but not adults, showed the same effect three weeks post-lesion, while no functional DAT-changes were detected after nine weeks. Measurements taken before and after administration of GBR 12909 also suggest additional regulatory mechanisms, which appear with serotonergic lesions and reduced DAT-function. The results of this study show, that the serotonergic and dopaminergic systems have a close interaction and interdependence. The importance of the dopamine system for the striatal and general basal ganglia functions emphasises necessity of understanding regulative control mechanisms. The demonstrated age-dependent effect is in agreement with studies on aging processes of the CNS, which describe anatomical, biochemical and electrophysiological changes. It appears therefore that functional disturbances are compensated by various regulatory mechanisms, dependent on age. The data of this study do not allow extensive interpretation. However, based on the knowledge of the interaction of the serotonin and dopamine transmission systems, one could suggest that the recorded changes of dopamine transmission are produced as a compensatory effort of the CNS to balance out the deficit of central serotonin

The expression of embryo maturation genes in wheat and the role of abscisic acid

A set of genes which show developmental and tissue specificity are expressed late in embryo maturation during grain formation in wheat (Triticum aestivum). Two members of this maturation gene set (MGS) are Em and triticin, a 7S globulin. Results presented here show that during embryogenesis, the expression of Em mRNA and polypeptide is temporally associated with increasing levels of the plant growth regulator abscisic acid (ABA). In the absence of elevated ABA levels, neither the mRNA nor the polypeptide for Em or triticin are detected at other developmental stages or in non-embryonic tissues. In situ hybridization shows that Em mRNA is localized in the embryo axis of the developing grain with high amounts concentrated in the shoot and root apices. Absence of Em mRNA in the scutellum and endosperm, the embryo storage organs, suggests that the function of Em in not one of a storage protein. However, mRNA levels of Em and triticin increase in response to higher levels of ABA at other stages of vegetative development. When ABA is supplied to germinating seedlings, mRNA for both Em and triticin accumulate. Some seed globulin proteins also accumulate in germinating seedlings after exposure to ABA. Em mRNA accumulation coincides with the pattern of increasing endogenous ABA concentrations in dehydrating seedling shoots. However, neither Em nor seed globulin polypeptides are detected in dehydrating tissue. These results suggest that ABA promotes MGS transcription or mRNA stability, in tissues other than embryos, but other factors control tissue specific expression at the polypeptide level. Desiccation of the embryo during normal grain development does not appear to be a trigger to prevent expression of MGS mRNA in response to ABA in non-embryonic tissue. However, desiccation may serve to alter the metabolic environment, preventing MGS polypeptides from accumulating. The implications of these findings on the proposed function of the MGS gene products and their regulation during development are discussed

Germania and alumina dopant diffusion and viscous flow effects at preparation of doped optical fibers

We report on germania and alumina dopant profile shift effects at preparation of compact optical fibers using packaging methods (Stack-and-Draw method, Rod-in-Tube (RiT) technique). The sintering of package hollow volume by viscous flow results in a shift of the core-pitch ratio in all-solid microstructured fibers. The ratio is increased by about 5% in the case of a hexagonal package. The shift by diffusion effects of both dopants is simulated for typical slow speed drawing parameters. Thermodynamic approximations of surface dissociation of germania doped silica suggest the need of an adequate undoped silica barrier layer to prevent an undesired bubble formation at fiber drawing. In contrast, alumina doping does not estimate critical dissociation effects with vaporous aluminium oxide components. We report guide values of diffusion length of germania and alumina for the drawing process by kinetic approximation. The germania diffusion involves a small core enlargement, typically in the sub-micrometer scale. Though, the alumina diffusion enlarges it by a few micrometers. A drawn pure alumina preform core rod transforms to an amorphous aluminosilicate core with a molar alumina concentration of only about 50% and a non-gaussian concentration profile

Ethical Issues in the New Digital Era: The Case of Assisting Driving

Mobility is associated with driving a vehicle. Age-related declines in the abilities of older persons present certain obstacles to safe driving. The negative effects of driving cessation on older adults’ physical, mental, cognitive, and social functioning are well reported. Automated driving solutions represent a potential solution to promoting driver persistence and the management of fitness to drive issues in older adults. Technology innovation influences societal values and raises ethical questions. The advancement of new driving solutions raises overarching questions in relation to the values of society and how we design technology (a) to promote positive values around ageing, (b) to enhance ageing experience, (c) to protect human rights, (d) to ensure human benefit and (e) to prioritise human well-being. To this end, this chapter reviews the relevant ethical considerations in relation to assisted driving solutions. Further, it presents a new ethically aligned system concept for assisted driving. It is argued that human benefit, well-being and respect for human identity and rights are important goals for new automated driving technologies. Enabling driver persistence is an issue for all of society and not just older adult

Driver Persistence, Safety and Older Adult Self-efficacy: Addressing Driving Challenges Using Innovative Multimodal Communication Concepts

New assisted driving technology provides a solution to enabling driver persistence while also addressing older adult fitness to drive issues. The proposed driver assistance system follows a detailed literature review, an analysis of secondary data, and the specification of a solution using human machine interaction (HMI) design methods. Overall, the assisted driving concept follows from a principled/ethical perspective in relation to promoting self-efficacy and enablement for older adults. The system is conceptualized as a supportive friend or ‘co-pilot’. It is argued that the use of new car-based sensors, along with machine learning intelligence and novel multimodal HMI communication methods will enable driver persistence while also promoting older adult self-efficacy and positive ageing

Modelling tree density effects on provisioning ecosystem services in Europe

Agroforestry systems, in which trees are integrated in arable or pasture land, can be used to enable sustainable food, material, and energy production (i.e. provide provisioning ecosystem services) whilst reducing the negative environmental impacts associated with farming. However, one constraint on the uptake of agroforestry in Europe is a lack of knowledge on how specific agroforestry designs affect productivity. A process-based biophysical model, called Yield-SAFE, was used: (1) to quantify the food, material and biomass energy production of four contrasting case study systems in Europe in a common energy unit (MJ ha−1), and (2) to quantify how tree density determined the supply of provisioning ecosystem services. The Yield-SAFE model was calibrated so that simulated tree and crop growth fitted observed growth data for reference monoculture forestry, pasture, and arable systems. The modelled results showed that including trees in pasture or arable systems increased the overall accumulated energy of the system in comparison with monoculture forestry, pasture, and arable systems, but that the accumulated energy per tree was reduced as tree density increased. The greatest accumulated energy occurred in the highest tree density agroforestry system at all the case study sites. This suggests that the capture of environmental resources, such as light and water, for obtaining provisioning services is most effective in high density agroforestry systems. Further modelling should include tree canopy effects on micro-climatic and the impact this has on pasture, crop, and livestock yields, as well as the impact of tree density on the economic value and management of the different systems

Interrogating marine virus-host interactions and elemental transfer with BONCAT and nanoSIMS-based methods

While the collective impact of marine viruses has become more apparent over the last decade, a deeper understanding of virus-host dynamics and the role of viruses in nutrient cycling would benefit from direct observations at the single-virus level. We describe two new complementary approaches - stable isotope probing coupled with nanoscale secondary ion mass spectrometry (nanoSIMS) and fluorescence-based biorthogonal non-canonical amino acid tagging (BONCAT) - for studying the activity and biogeochemical influence of marine viruses. These tools were developed and tested using several ecologically relevant model systems (Emiliania huxleyi/EhV207, Synechococcus sp. WH8101/Syn1, and Escherichia coli/T7). By resolving carbon and nitrogen enrichment in viral particles, we demonstrate the power of nanoSIMS tracer experiments in obtaining quantitative estimates for the total number of viruses produced directly from a particular production pathway (by isotopically labeling host substrates). Additionally, we show through laboratory experiments and a pilot field study that BONCAT can be used to directly quantify viral production (via epifluorescence microscopy) with minor sample manipulation and no dependency on conversion factors. This technique can also be used to detect newly synthesized viral proteins. Together these tools will help fill critical gaps in our understanding of the biogeochemical impact of viruses in the ocean

Celebration of the life and work of Professor Berry Mayall 1936-2021

The celebration was held in-person and online on 4th April 2023 in the Jeremy Bentham Room, University College London. The event was chaired by Dr Kirrily Pells and Dr Ginny Morrow. Dr Rosa Mendizabal-Espinosa organised the booking and online support. Among those who attended were members of Berry’s family and 30 students on the MA course Childhood Studies and Children's Rights, co-founded by Berry in 2003. Professor Priscilla Alderson edited this report