Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Univ., 2002. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol inst., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 7 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 56-68).

Le MPH est le médicament le plus prescrit pour le traitement du trouble déficitaire de l'attention/hyperactivité (TDA/H). Sa prescription de l’enfance à l’âge adulte et notamment chez les femmes en âge de procréer soulève des questions sur les effets à long terme d’un tel traitement sur le cerveau en développement. À ce jour, aucune information n’est disponible concernant la présence ou non de modifications neurobiologiques à l’âge adulte consécutives à une exposition prénatale au MPH. Nous avons utilisé un modèle d'exposition prénatale au MPH chez le rat pour étudier les conséquences d'un tel traitement sur le fonctionnement du cerveau adulte. L'imagerie scintigraphique a été réalisée pour comparer les profils métaboliques cérébraux des rats exposés en prénatal au MPH vs témoins. L'aspect structural de leur système dopaminergique a été évalué avec un immunomarquage de la TH et l'aspect fonctionnel à l'aide de microdialyse in vivo et d'immunohistochimie c-Fos dans des conditions basales et après stimulation dopaminergique. Parallèlement, l'évaluation comportementale de ces animaux vis-àvis de récompense naturelle ou synthétique ainsi que leur réactivité vis-à-vis de l'effet locomoteur de la cocaïne a été étudiée. Les animaux exposés en prénatal au MPH affichent des altérations neurobiologiques structurales et fonctionnelles associées au système dopaminergique et à sa réactivité suite à une administration de cocaïne. Nos résultats montrent aussi que ces animaux présentent une altération de la préférence et de la motivation au sucre (renforçateur naturel) alors qu'aucune différence de motivation pour s'auto-administrer de la cocaïne (renforçateur synthétique) n'a été décelée. Cependant, ces animaux montrent une baisse de sensibilité aux effets locomoteurs de la cocaïne. À notre connaissance, notre étude préclinique est la première qui rapporte des modifications neurobiologiques à long terme après une exposition prénatale au MPH. / MPH is the gold standard medication for Attention-Deficit/Hyperactivity Disorders (ADHD). MPH extended prescription to adult patients raises the question of MPH's long-term effects during brain development when it is administered to ADHD women of childbearing age. There is still no information regarding the neurobiological modifications consecutive to a prenatal exposure to MPH. We used a rat model of prenatal exposure to MPH to investigate the consequences of such treatment on adult brain functioning. Rats prenatally exposed to MPH displayed structural and functional neurobiological alterations related to dopaminergic system and its reactivity to cocaine administration. Furthermore, these animals showed behavioral changes towards natural or synthetic rewards. To our knowledge, this is the first preclinical study reporting long-lasting neurobilogical modifications after a prenatal exposure to MPH.

abstract: Dopamine (DA) is a neurotransmitter involved in attention, goal oriented behavior, movement, reward learning, and short term and working memory. For the past four decades, mathematical and computational modeling approaches have been useful in DA research, and although every modeling approach has limitations, a model is an efficient way to generate and explore hypotheses. This work develops a model of DA dynamics in a representative, single DA neuron by integrating previous experimental, theoretical and computational research. The model consists of three compartments: the cytosol, the vesicles, and the extracellular space and forms the basis of a new mathematical paradigm for examining the dynamics of DA synthesis, storage, release and reuptake. The model can be driven by action potentials generated by any model of excitable membrane potential or even from experimentally induced depolarization voltage recordings. Here the model is forced by a previously published model of the excitable membrane of a mesencephalic DA neuron in order to study the biochemical processes involved in extracellular DA production. After demonstrating that the model exhibits realistic dynamics resembling those observed experimentally, the model is used to examine the functional changes in presynaptic mechanisms due to application of cocaine. Sensitivity analysis and numerical studies that focus on various possible mechanisms for the inhibition of DAT by cocaine provide insight for the complex interactions involved in DA dynamics. In particular, comparing numerical results for a mixed inhibition mechanism to those for competitive, non-competitive and uncompetitive inhibition mechanisms reveals many behavioral similarities for these different types of inhibition that depend on inhibition parameters and levels of cocaine. Placing experimental results within this context of mixed inhibition provides a possible explanation for the conflicting views of uptake inhibition mechanisms found in experimental neuroscience literature. / Dissertation/Thesis / Ph.D. Applied Mathematics for the Life and Social Sciences 2012

Ce projet de thèse concerne les 2 principales complications rencontrées en pratique clinique dans les suites de l’angioplastie-stenting artériel : la resténose et la thrombose aigüe. Pour remédier à ce problème, des stents enrobés d’agents antiprolifératifs sont déjà sur le marché, mais leurs résultats restent décevants en raison de l’augmentation du taux de thrombose tardive intrastent (RR 1,2 vs stent nu) à l’origine d’une surmortalité (RR 1,32 vs stent nu) [Lagerqvist Bo et al., N Eng J Med 2007]. Dans ce travail, nous proposons d’immobiliser sur le stent une ancre spécifique au substrat métallique soit pour immobiliser i) la molécule thérapeutique, soit pour immobiliser ii) une matrice polymère sur laquelle sera adsorbée une molécule thérapeutique dans le cas d’un système à libération prolongée; cette dernière ciblant la resténose et la thrombose. Cette ancre, issue des protéines permettant l’accroche des moules marinières à tout type de substrat [Waite JH et al., Science 1981], est la base commune pour une immobilisation par liaisons covalentes de la molécule thérapeutique ou du système polymère. La première partie du projet concernait la mise au point de l’ancre chimique spécifique dans le cadre d’une immobilisation de surface. Avec cette technique d’immobilisation, l’ancre dopamine inclue un ester activé, permettant de générer un polymère de longueur de chaine contrôlé et capable d’adsorber une quantité contrôlée et définie de molécule thérapeutique [C Zobrist et al., Macromolecules 2011]. Ce polymère de N-(Acryloyloxy)succinimide a pu être caractérisé et couplé à une molécule de glucosamine, protéoglycane aux caractéristiques pertinentes dans la problématique développée. Ce modèle a été validé sur le plan chimique et biologique. Les résultats restaient décevants concernant la prolifération des cellules musculaires lisses qui sont les cellules cibles dans la resténose.L’ancre dopamine a par la suite était modifiée dans le but de permettre le greffage d’autres fonctions chimiques, notamment amines et acides. Elle a finalement été utilisée en conditions basiques (pH 8,5) permettant d’obtenir une polydopamine [Lee et al., Science 2007].Cette polydopamine a permis l’interaction sur notre surface d’un polymère bien connu au sein de notre unité et déjà employé pour la fonctionnalisation des tissus dans le domaine biomédical, le polymère de cyclodextrine (CD) [Martel B et al., European Polymer Journal 1995]. Les CD sont des oligosaccharides cycliques sous forme de cône tronqué possédant une cavité hydrophobe interne et des groupements hydroxyles à l’extérieur engendrant un caractère hydrophile. Cette structure cyclique leur confère la capacité de former des complexes d’inclusion réversibles avec un grand nombre de molécules hydrophobes. Elles peuvent donc stocker une molécule thérapeutique en grande quantité et ont la capacité de la libérer dans le temps.L’ensemble des paramètres du procédé de fonctionnalisation permettant l’adsorption de ces 2 couches successives : polydopamine et polymère de CD a pu être optimisé. La complexation de deux molécules thérapeutiques d’intérêt à notre plateforme fonctionnalisée a pu être réalisée: la simvastatine et le paclitaxel. La simvastatine, de la famille des statines, est une molécule pléïotrope, régulatrice de la dysfonction endothéliale ; elle limite la réaction inflammatoire locale impliquée à la fois dans les phénomènes de resténose et de thrombose [Balk EM et al., Am J Med. 2004]. Le paclitaxel est un agent immunosuppresseur et antiprolifératif limitant la prolifération de la néointima [Creel CJ et al., Circ Res 2000]. Nous avons comparé notre plateforme avec un système actuellement sur le marché, le système PTX « polymer-free » mise au point par Dake et al. [Dake et al., JVIR 2011]. [...] / This work has focused on 2 major issues encountered after angioplasty and stenting of arterial occlusive disease: intra-stent restenosis and thrombosis.To prevent these postoperative complications, drug eluting stents (DES) have been developed and are currently available for clinical use; they elute antiproliferative drugs overtime which limit smooth muscle cells migration and proliferation. Long-term results of DES are jeopardized by a high late in-stent thrombosis rate (RR 1.2 vs bare metal stent) which is correlated to a higher late death rate (RR 1.32 vs bare metal stent) [Lagerqvist Bo et al., N Eng J Med 2007]. We present an original process of immobilization of a specific anchor on a metallic substrate which has the ability to directly immobilize drugs onto the metallic surface. It can also indirectly using specific biocompatible polymers load drugs onto the metallic surface which would be eluted overtime. The target for both systems is the cellular response involved in the restenosis and thrombosis process.This specific anchor, which is dedicated to several substrates, is developed from marine mussels gel [Waite JH et al., Science 1981]. It is currently a common basis for covalent immobilization of drugs and/or polymer systems able to sustain drug release.The first part of the project involved the development of a specific chemical anchor through an immobilization surface strategy. This dopamine anchor includes an activated ester, which is the starting point of the creation of a polymer with defined and controlled chain length. The generated polymer of N-(Acryloyloxy)succinimide has the ability to absorb a controlled and defined amount of drug; it has been linked with glucosamine to illustrate the potential of the system - glucosamine is a proteoglycan from the extracellular matrix of the arterial wall. The system has then been characterized and optimized for every parameters; unfortunately, results were not as good as expected regarding SMC proliferation.The Dopamine anchor has thus been modified to allow interactions with more chemical functions, including amino- and carboxylic functions. Finally, we used it under alkaline conditions (pH=8.5) where dopamine generated a network of polydopamine [Lee et al., Science 2007].Afterwards, we report an original functionalization of metallic surfaces with a hydrophilic, biocompatible and biodegradable cyclodextrin based polymer. This polymer acts as a reservoir for hydrophobic drugs allowing the sustained release of anti-proliferative drugs and promotes natural arterial wall healing. The polymer of CD is well-known in our research department and has already been used as an active coating onto textile for vascular devices [Martel B et al., European Polymer Journal 1995]. In this setting polydopamine was applied as a first coating layer onto the metallic surface in order to promote a strong anchorage of a cyclodextrin based polymer that was “in situ” generated from the native cyclodextrins and citric acid as a crosslinking agent through a polycondensation reaction. After optimization of the grafting process, the ability of this system to act as a drug eluting system was evaluated with paclitaxel (PTX) and simvastatine. PTX is a reference drug for current vascular drug eluting stents [Creel CJ et al., Circ Res 2000]. PTX is currently coated on vascular stents with a “polymer-free” method [Dake et al., JVIR 2011]. It is a highly lipophilic antiproliferative drug, and that “polymer free” system was compared as a positive control to our functionalized scaffold. We compared the results of our functionalized surface loaded of PTX and Simvastatin. Simvastatin is a pleiotropic molecule with targeted actions on arterial disease, inflammatory process and dyslipidemia [Balk EM et al., Am J Med. 2004]. [...]

Dysfunction of central dopaminergic systems has been implicated in neuroendocrine, neurodegenerative and psychiatric disorders. Monoamine oxidase and catechol-Omethyltransferase represent the key catabolic enzymes of dopamine, terminating neurotransmission following synaptic release of this catecholamine. Thus, both enzymes have been associated with the pathology of dopaminergic systems and represent therapeutic targets elf enormous clinical importance. Some neuroendocrine and circadian effects of melatonin have been attributed to an antidopamimetic effect of this pineal hormone in the hypothalamus and pituitary. Furthermore, both melatonin and dopamine modulate the behavioural output of the mesencephalic dopaminergic pathways of the basal ganglia, including movement disorders. However, the biochemical basis for the tonic inhibitory effect of melatonin in the nigro-striatal pathway has been poorly delineated. Thus, this study determined whether melatonin influences dopaminergic function in the corpus striatum of the Wistar rat by modulating monoamine oxidase and catecholO- methyltransferase activity. Reciprocally, the putative existence of an intrapineal dopaminergic system was investigated by determining the effect of selective dopaminergic agents, R-( -)apomorphine, haloperidol and dopamine, on indole metabolism of the pineal gland. The akinetic state of drug-induced catalepsy was employed as an animal model of Parkinson's disease to probe the neurotransmitter systems involved in the behavioural effects of melatonin. Indole metabolism was a reliable indicator of state-dependent metabolic fluxes in pineal gland function. These included a robust diurnal and seasonal variation in N-acetylserotonin and melatonin biosynthesis, and photoperiod- and drug-induced alterations of Inftabolism. The predominant changes could be attributed to an effect on serotonin N-acetyltransferase activity and/or the melatoninl5-methoxytryptophol ratio. Pineal 5-methoxyindole biosynthesis was determined primarily by the bioavailability of the corresponding 5-hydroxyindole and its affinity for hydroxyindole-O-methyltransferase. Evidence was found for the negative feedback or paracrine control of pineal indole metabolism by melatonin. A high inter-individual variability was observed in the biosynthesis of N-acetylserotonin and melatonin biosynthesis, and the weight of the pineal glands. Accordingly, the rats could be classified as either high or low capacity producers of these two indoles. R-(-)-apomorphine and dopamine in vitro, but not acute haloperidol in vivo, had dose- and phase-dependent effects on pineal indole metabolism. The predominant effect was a suppression of the scotophase-dependent induction ofN-acetylserotonin and melatonin biosynthesis by dopamine and R-( -)-apomorphine. It is postulated that these agonists inhibited nocturnal N-acetyltransferase activity via postsynaptic pineal D2 or D2-like receptors. The observed modulatory nature of the intrapineal dopaminergic system suggests that dopamine may be involved in the long-term regulation of pineal indole biosynthesis. Several lines of evidence are presented that the activity of striatal monoamine oxidase A and catechol-O-methyltransferase, represented predominantly by the soluble isoform, is statedependent and regulated in vivo by endogenous melatonin. Firstly, both enzymes showed a daynight variation in activity. Secondly, acute and subchronic administration and photoperiod manipulation studies indicated that both exogenous and endogenous melatonin inhibited each enzyme in a chronotypic fashion, with a more robust effect against catechol- -methyltransferase. The intensity of the in vivo effects was critically dependent on the dose, duration, route and the phase-timing of administration during the light dark cycle, and the length of the exposure to constant light. Melatonin in vitro had no effect on basal or Mg2+ -induced catechol-Omethyltransferase activity. Thus, it is proposed that the in vivo effects of the hormone can be attributed to a time-dependent change in the amount of active molecules of this enzyme. In contrast, melatonin and numerous other endogenous indolic compounds were found to be reversible inhibitors of striatal monoamine oxidase A in vitro. Structure-activity modeling revealed that the 5-methoxy moiety on the indole nucleus and substitution of the free primary amine of these compounds were the principal determinants of the potency and time-dependency of inhibition. Thus melatonin most likely has a direct inhibitory effect in vivo at the level of the active site of monoamine oxidase A. Exogenous melatonin alone had no cataleptogenic potential whereas a variety of behavioural responses were observed following intraperitoneal administration of y-hydroxybutyrate. The latter responses were state-dependent with day-night variations in intensity. Furthermore, yhydroxybutyrate stimulated melatonin biosynthesis during the photophase both in vitro and in vivo. These results point to a possible involvement of melatonin in the behavioural and neurochemical effects of y-hydroxybutyrate. Thus the general conclusion is that dopamine and melatonin display functional antagonism at the level of the pineal gland and corpus striatum of the Wistar rats. Therefore melatonin may be an important homeostatic modulator of dopaminergic neurotransmission throu~out the central nervous system. Furthermore, the putative existence of a functional pineal-striatal axis would greatly strengthen the argument for a holistic concept of brain homeostasis. The ability of endogenous melatonin to regulate monoamine oxidase A and catechol-O-methyltransferase may represent an alternative strategy for the treatment of disorders associated with these enzymes.