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Physiopathologie respiratoire et cardiovasculaire suite à un trauma spinal cervical chez le rongeur

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Les traumas spinaux cervicaux induisent non seulement une insuffisance respiratoire en raison de la déafférentation des motoneurones innervant le diaphragme, mais aussi des déficits cardiovasculaires dus à la réduction des efférences sympathiques innervant le cœur et le système vasculaire. La mise au point de thérapeutiques visant à améliorer ces fonctions suite à une lésion spinale est donc nécessaire. Une partie de ce travail doctoral a donc consisté à améliorer les connaissances sur la physiopathologie des traumas spinaux. Au niveau fonctionnel, nous avons montré qu’en plus d’une paralysie hémidiaphragmatique permanente, une hémisection spinale unilatérale en C2 induit aussi un déficit systolique évalué par échocardiographie et caractérisée par une réduction de la fraction d’éjection du ventricule gauche. Cette lésion partielle conduit de plus à une réponse inflammatoire au niveau des motoneurones phréniques (localisés dans la moelle épinière C3-C6), mais aussi au niveau lésionnel (C1-C3), où la production de pièges extracellulaires a pu être observée par les neutrophiles infiltrants et la microglie activée par cytométrie en flux. La seconde partie de ce travail doctoral s’est concentrée sur l’évaluation de l’efficacité de la stimulation magnétique transcrânienne répétée sur la neuromodulation du réseau respiratoire. Nous avons ainsi montré que délivré de façon aigu, notre protocole permet d’augmenter l’excitabilité du réseau phrénique. Délivré de façon chronique après trauma spinal, il permet de renforcer l’activité de l’hémidiaphragme intact afin de mieux compenser pour la perte d’activité de l’hémidiaphragme lésé. Malgré une absence d’effet sur l’activité basale de l’hémidiaphragme paralysé, un renforcement des voies croisées phréniques a pu être observé après traitement, laissant entrevoir de nouvelles thérapeutiques potentielles visant à induire une récupération fonctionnelle respiratoire après trauma spinal cervical.
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