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Parkinson's disease (PD) is one of the most common motor neurodegenerative diseases, affecting 1-2% of the world's population over the age of 65. It is characterised by a loss of dopamine neurons within the substantia nigra, which is an integral part of the basal ganglia (BG) where dopamine is the most important modulating neurotransmitter. As the BG is primarily involved with the execution of movement, the lack of dopamine input results in dysfunctional motor control. The current PD treatment, L-DOPA, improves these motor symptoms, however only provides patients 5 to 10 years of improved quality of life before debilitating side effects, often worse than the original symptoms, begin. The neuropeptide substance P (SP) is found in high concentration in the substantia nigra, and BG in general, where it is involved in dopamine release. In the late stages of PD, SP content within the substantia nigra and BG is decreased, thus implicating SP in the pathophysiology of PD. However, SP production has not been examined in the early stages of PD when dopaminergic degeneration is first initiated. This thesis therefore sought to characterise the role of SP in dopaminergic degeneration in an experimental model of early PD, the 6-hydroxydopamine model in rats. In contrast to the prevailing dogma that a decline in SP is associated with neurodegeneration in PD, this thesis demonstrates that SP is actually increased within the striatum in early PD, particular in perivascular tissue and within surviving dopaminergic neurons during the degenerative process. Increasing exposure of the dopaminergic neurons to SP, either by inhibition of substance P breakdown with Captopril or by direct injection with SP, exacerbated the disease progression as indicated by more profound neurogenic inflammation, functional deficits and increased dopaminergic cell death. However, when SP was inhibited by treatment with a SP NK₁ receptor antagonist, dopaminergic neurons were conserved, the inflammatory response was reduced and motor function was returned to near normal levels. We conclude that SP is increased in early PD, and that increased SP plays an important role in the degenerative process, specifically, in the genesis of BBB breakdown and initiation of neurogenic inflammation. Treatment with an NK1 antagonist may thus represent a novel therapeutic approach to early stage Parkinson’s disease. / Thesis (Ph.D.) -- University of Adelaide, School of Medical Sciences, 2009

Parkinson's disease (PD) is one of the most common motor neurodegenerative diseases, affecting 1-2% of the world's population over the age of 65. It is characterised by a loss of dopamine neurons within the substantia nigra, which is an integral part of the basal ganglia (BG) where dopamine is the most important modulating neurotransmitter. As the BG is primarily involved with the execution of movement, the lack of dopamine input results in dysfunctional motor control. The current PD treatment, L-DOPA, improves these motor symptoms, however only provides patients 5 to 10 years of improved quality of life before debilitating side effects, often worse than the original symptoms, begin. The neuropeptide substance P (SP) is found in high concentration in the substantia nigra, and BG in general, where it is involved in dopamine release. In the late stages of PD, SP content within the substantia nigra and BG is decreased, thus implicating SP in the pathophysiology of PD. However, SP production has not been examined in the early stages of PD when dopaminergic degeneration is first initiated. This thesis therefore sought to characterise the role of SP in dopaminergic degeneration in an experimental model of early PD, the 6-hydroxydopamine model in rats. In contrast to the prevailing dogma that a decline in SP is associated with neurodegeneration in PD, this thesis demonstrates that SP is actually increased within the striatum in early PD, particular in perivascular tissue and within surviving dopaminergic neurons during the degenerative process. Increasing exposure of the dopaminergic neurons to SP, either by inhibition of substance P breakdown with Captopril or by direct injection with SP, exacerbated the disease progression as indicated by more profound neurogenic inflammation, functional deficits and increased dopaminergic cell death. However, when SP was inhibited by treatment with a SP NK₁ receptor antagonist, dopaminergic neurons were conserved, the inflammatory response was reduced and motor function was returned to near normal levels. We conclude that SP is increased in early PD, and that increased SP plays an important role in the degenerative process, specifically, in the genesis of BBB breakdown and initiation of neurogenic inflammation. Treatment with an NK1 antagonist may thus represent a novel therapeutic approach to early stage Parkinson’s disease. / Thesis (Ph.D.) -- University of Adelaide, School of Medical Sciences, 2009

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains vii, 43 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 31-41).

L’existence de douleurs neuropathiques et/ou de perte de la sensibilité douloureuse sont souvent le reflet d’une neuropathie sensitive affectant plus particulièrement les fibres nerveuses sensitives amyélinique Aδ et C, dites neuropathie des petites fibres (NPF). Ces fibres innervent, notamment, le derme et l’épiderme de la peau. Elles communiquent la sensibilité thermique et algique au système nerveux central et contribuent à l’homéostasie cutanée, entre autres, par la libération de neuropeptides en périphérie. De nombreuses pathologies sont associées à une altération de ces petites fibres dans la peau. Deux pathologies impliquant une NPF ont été étudiées au cours de ce travail : les escarres et la maladie de Charcot-Marie-Tooth type 1A. Un travail expérimental a été réalisé chez la souris pour répondre à la question suivante ; est-ce qu’une seule atteinte des fibres nociceptives, responsables de la perte de sensibilité peut entraîner un déséquilibre de l’homéostasie cutanée, responsable de l’apparition des escarres ? La mise en place d’un modèle de neuropathie sensitive fonctionnelle réversible a permis de mettre en en évidence l’implication des neuropeptides, substance P (SP) et « calcitonin gene-related peptide » (CGRP), libérés par les fibres nerveuses cutanées, dans la formation d’ulcères de pression. Un traitement préventif à la rhEPO (Recombinant Human Erythropoietin) dans ce modèle associant une neuropathie et des plaies de pression, protège la peau contre une pression ischémiante induisant une escarre par son effet neuroprotecteur sur les petites fibres cutanées. L’association CMT1A et NPF a été étudiée à partir de biopsies cutanées humaines. La quantification des fibres intraépidermiques révèle que 48% des patients CMT1A sont atteints d’une NPF. L’analyse des biopsies cutanées révèle également une altération du nombre et de la morphologie de cellules de Langerhans dans la maladie de CMT1A. L'ensemble de ces résultats confirme l'intérêt de l'étude des petites fibres dans des pathologies variées et confirme le potentiel thérapeutique neuroprotecteur de l'EPO / The neuropathic pain and/or hypoalgesia often reflect a sensory neuropathy that affects particularly sensory, Aδ (thinly myelinated) and C (unmyelinated) nerve fibers. This kind of neuropathy is named "small fiber neuropathy" (SFN). These small fibers innervate the dermis and epidermis. C and Aδ free nerve endings respond to a variable range of stimuli including mechanical, thermal and pain stimuli. They conduct nociceptive signals to central nervous system and contribute to skin homeostasis, among others, by the release of neuropeptides in the periphery. Many diseases are associated with an alteration of these cutaneous small fibers. Two pathologies involving SFN were studied in this work: pressure ulcers and Charcot-Marie-Tooth disease Type 1A (CMT1A). Experimental studies on mice were performed to determine if impairment of nociceptive fibers could lead to an imbalance of skin homeostasis and could be involved in development of pressure ulcers, apart from its role in pain signal transduction. A functional reversible sensory neuropathy mouse model was set up and helped to demonstrate the involvement of the neuropeptides, substance P (SP) and "calcitonin gene-related peptide" (CGRP), released by cutaneous nerve fibers in the formation of pressure ulcers. By its neuroprotective effect on small nerve fibers, a preventive rhEPO (Recombinant Human Erythropoietin) treatment in this model protects the skin against an ischemic pressure-induced Stage 2 ulcer. The CMT1A and SFN association has been studied from human skin biopsies. Quantification of intraepidermal nerve fibers reveals that 48% of CMT1A patients have a SFN. The analysis of skin biopsies also revealed an alteration in the number and morphology of Langerhans cells in CMT1A disease. All these results confirm the interest of the study of small fibers in various pathologies and confirm the neuroprotective therapeutic potential of EPO.

La sécrétion d'aldostérone par la glande surrénale est principalement contrôlée par le système rénine-angiotensine circulant (SRA) et la kaliémie. La synthèse de l'aldostérone est également influencée par les facteurs paracrines intra-surrénaliens, y compris les neuropeptides. En particulier, les tachykinines, comme la substance P (SP), peuvent être libérées par les terminaisons nerveuses dans le cortex surrénalien. Le rôle de la SP dans la régulation de la fonction surrénalienne a été évalué chez l'animal mais rarement étudié chez l'homme. Le but de la présente étude est d'explorer le rôle de la SP dans le contrôle de la synthèse des minéralocorticoïdes dans la glande surrénale humaine. Des expériences in vitro conduites dans des échantillons surrénaliens normaux révèlent l'expression de SP codée par TAC1 qui est détecté par immunohistochimie dans des fibres nerveuses non-adrénergiques non-cholinergiques dans la zone glomérulée. Les fibres SP-positives établissent des contacts étroits avec des cellules productrices d'aldostérone qui expriment le récepteur NK1 (NK1R), récepteur de la SP. La SP stimule la production d'aldostérone à partir de cellules corticosurrénales cultivées, un effet qui est inhibé par l'aprépitant, antagoniste NK1R. L'action de la SP est relayée par la voie ERK et implique une régulation à la hausse de plusieurs gènes codant pour des enzymes de la stéroïdogénèse. Le rôle physiologique de la SP dans la régulation de la sécrétion d'aldostérone a été évalué à l'aide d'un essai clinique prospectif, contrôlé par placebo, de l'impact de l'aprépitant sur les concentrations plasmatiques et urinaires d'aldostérone chez des volontaires sains. L'aprépitant a réduit la production quotidienne d'aldostérone et la concentration plasmatique d'aldostérone (CPA) dans le décubitus, mais n'a pas modifié les CPA en position debout. Ces données montrent que la SP exerce un tonus stimulant sur la production d'aldostérone chez l'homme. / Aldosterone secretion by the adrenal gland is principally under control of the circulating renin-angiotensin system (RAS) and kalemia. Aldosterone synthesis is also influenced by intra-adrenal paracrine factors including neuropeptides. Especially, tachykinins, like substance P (SP), can be released by nerve endings in the adrenal cortex. The role of SP in the regulation of the adrenal function has been evaluated in animals but only scarcely investigated in humans. The aim of the present study is to explore the role of SP in the control of mineralocorticoid synthesis in the human adrenal gland. In vitro experiments conducted in normal adrenal samples reveal expression of the TAC1 encoding SP which is detected by immunohistochemistry in non adrenergic non cholinergic nerve fibres in the zona glomerulosa. SP-positive fibres establish close contacts with aldosterone-producing cells which express the SP receptor, i.e. the NK1 receptor (NK1R). SP stimulates aldosterone production from cultured adrenocortical cells, an effect which is inhibited by the NK1R antagonist aprepitant. The action of SP is mediated by the ERK pathway and involves upregulation of several genes encoding steroidogenic enzymes. The physiological role of SP in the regulation of aldosterone secretion was further assessed through a prospective clinical placebo-controlled trial investigating the impact of aprepitant on plasma and urine aldosterone levels in healthy volunteers. Aprepitant reduced daily aldosterone production and plasma aldosterone concentration (PAC) in recumbency but did not modify PAC in upright position. These data show that SP exerts a stimulatory tone on aldosterone production in man.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Derek A. Mosier / The bovine respiratory disease complex (BRDC) is a major concern for cattle producers in the United States and worldwide. One of the most costly and deadly components of BRDC is bovine pneumonic pasteurellosis (BPP) caused by Mannheimia haemolytica. The initial pulmonary inflammation associated with BPP is a characteristic serofibrinous exudation into the lung, which is believed to be induced by M. haemolytica virulence factors such as lipopolysaccharide (LPS) and leukotoxin (LKT) and host cytokines and chemokines such as tumor necrosis factor – α, interleukin – 1β, and interleukin – 8. However, these pulmonary changes often occur before virulence factors or cytokines are substantial components of the pulmonary microenvironment. Other proinflammatory molecules such as substance P (SP) may be involved in the pathogenesis of the peracute serofibrinous exudation of BPP. SP is an 11 amino acid long neuropeptide that is a neurotransmitter of pain that can be released from sensory nerves into tissues to cause neurogenic inflammation. Neurogenic inflammation is characterized by serofibrinous exudation and leukocyte activation. SP-like immunoreactivity was present in the airways, alveolar septa, macrophages, endothelium, and peribronchial nerves in both pneumonic and normal bovine lung; however, SP-like immunoreactivity was increased in pneumonic compared to normal bovine lung due to increased immunoreactivity in macrophages. SP and the combination of SP with histamine and LPS increased the permeability of a calf pulmonary arterial endothelial cell line to Evans blue dye labeled albumin by 12.34%, 13.57%, and 22.03%, respectively compared to a cell control. Similarly, SP and the combination of SP and histamine increased the monolayer permeability of a bovine adrenal gland capillary endothelium by 8.27% and 16.69% compared to a cell control. The increase in permeability was due to endothelial cell shape change and the formation of intercellular gaps rather than cell death. However, SP does not increase the surface expression of the β2 integrin CD18 (the M. haemolytica LKT receptor) on bovine neutrophils nor does it increase LKT-induced leukocytotoxicity of bovine peripheral blood leukocytes. These findings indicate that SP may be a contributor to BPP in association with other cytokines.

À ce jour, les analgésiques de choix dans le traitement de la douleur sont toujours les composés opioïdergiques agissant sur le récepteur mu (MOPR), comme par exemple la morphine. Étant donné les effets secondaires indésirables observés avec ces agonistes, des alternatives ont été envisagées pour traiter la douleur adéquatement tout en réduisant les effets indésirables. Un rôle pour le récepteur opioïdergique delta (DOPR) a été proposé, car son activation engendre moins d'effets secondaires que MOPR. Cependant, la faible efficacité analgésique de ses agonistes limite son utilisation clinique. Les études menées dans le laboratoire du Pr Louis Gendron ont pour but principal d'étudier les rôles de DOPR, sa régulation et ses mécanismes d'action pour contrer la douleur. Chez les rongeurs, il est entre autre [i.e. autres] possible d'augmenter l'analgésie induite par les agonistes DOPR dans certaines conditions, comme suite à un traitement chronique avec un agoniste MOPR ou lors d'une douleur de type inflammatoire ou neuropathique. En conditions normales, DOPR semble séquestré au niveau intracellulaire, ce qui pourrait expliquer sa faible efficacité analgésique. Cependant, une augmentation de la disponibilité membranaire de DOPR semble corrélée à l'augmentation de ses effets analgésiques. Différentes hypothèses ont été proposées pour expliquer ce phénomène et ce mémoire présente un survol des différents mécanismes de régulation proposés pour DOPR en s'attardant principalement sur le rôle possible de la substance P. Ce neuropeptide a en effet été décrit comme étant essentiel pour permettre l'expression membranaire de DOPR et ainsi permettre l'analgésie via ce récepteur. Cependant, des différences dans la localisation de la substance P et de DOPR ont été soulevées. Mon étude évalue donc le rôle de la substance P dans l'analgésie produite par des agonistes DOPR dans un modèle de douleur inflammatoire. Les résultats obtenus ici démontrent que la substance P ne semblent [i.e. semble] pas essentielle pour permettre la compétence fonctionnelle de DOPR. Cela suggère donc l'existence de mécanismes de régulation de DOPR indépendants de la substance P. Il ne semble donc pas y avoir un seul et unique mécanisme responsable de la régulation de DOPR, différentes hypothèses sont explorées dans ce mémoire.

Background: Tendinosis is a painful chronic, degenerative condition characterized by objective changes in the tissue structure of a tendon. Hallmark features in tendinosis tendons include increased number of cells (hypercellularity), extracellular matrix (ECM) degradation and disorganized collagen. The progression of these pathological changes seen in tendinosis is neither well characterized nor fully understood. Studies have suggested that there are biochemical and mechanical elements involved in tendinosis. From a biochemical perspective, studies have shown that the tendon cells, tenocytes, produce a number of neuronal signal substances/neuromodulators, such as substance P (SP) and acetylcholine (ACh), traditionally thought to be confined to the nervous system. Furthermore, it has been shown that the expression of these neuromodulators is elevated in tendinosis tendons as compared to normal healthy tendons. Interestingly, studies on other tissue types have revealed that both SP and ACh can induce tissue changes seen in tendinosis, such as hypercellularity and collagen disorganization. From a mechanical angle, it has been suggested that overload of tendons, including extensive strain on the primary tendon cells (tenocytes), causes the degenerative processes associated with tendinosis. In vivo studies have shown that in overloaded tendons, the presence of neuromodulators is elevated, not least SP, which also precedes the development of the tissue changes seen in tendinosis. This further supports the importance of combining biochemical factors and mechanical factors in the pathogenesis of tendinosis. Hypotheses: In this thesis project, we hypothesize: 1) that neuromodulators, such as SP and ACh when stimulating their preferred receptors, the neurokinin 1 (NK-1 R) and muscarinic receptors (mAChRs), respectively, can cause increased tenocyte proliferation; 2) that the effects of SP and ACh on tenocyte proliferation converge mechanistically via a shared signalling pathway; 3) that mechanical loading of tenocytes results in increased production of SP by the tenocytes; and 4) that SP enhances collagen remodelling by tenocytes via NK-1 R. Model system: In vitro studies offer insight into the function of healthy tendon matrix and the etiology of tendinopathy. Using a cell culture model of human primary tendon cells, highly controlled experiments were performed in this thesis project to study a subset of biological and mechanical parameters that are implicated in tendinosis. The FlexCell® Tension System was used to study the influence of mechanical loading on tenocytes. As well, a collagen gel contraction assay was used to examine the intrinsic ability of tenocytes to reorganise type I collagen matrices under the influence of the neuromodulator SP. Results: The studies showed that exogenous administration of SP and ACh results in increased tenocyte proliferation that is mediated via activation of the ERK1/2 mitogenic pathway when the preferred receptors of SP and ACh, the NK-1 R and mAChRs, respectively, are stimulated. Furthermore, the studies resulted in the novel finding that SP and ACh both converge mechanistically via transforming growth factor (TGF)-β1 and that a negative feedback mechanism is present in which TGF-β1 downregulates the expression of mAChRs and NK-1 R. The studies also showed that SP can increase collagen remodelling and upregulate expression of genes related to tendinosis. Finally, it was established that tenocytes are mechanoresponsive by showing that cyclic mechanical loading increases the expression of SP by human tenocytes. Conclusions: This thesis work concludes that stimulation of NK-1 R and mAChRs results in proliferation of human tenocytes, which both involve the ERK1/2 signalling pathway. It also shows that SP and ACh converge mechanistically via TGF-β1 in their contribution to tenocyte proliferation. The role of hypercellularity in tendinosis tissue is unknown. Possibly, it has different roles at different stages of the disease. The findings also show that SP increases collagen remodelling, suggesting that increased SP not only results in hypercellularity but also contributes to the collagen morphology in tendinosis.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.